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BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Preoperative Opioid Use as a Predictor of Adverse Postoperative Self-Reported Outcomes in Patients Undergoing Spine Surgery Dennis Lee, MD, Sheyan Armaghani, MD, Kristin R. Archer, PhD, DPT, Jesse Bible, MD, David Shau, BS, Harrison Kay, BS, Chi Zhang, BA, Matthew J. McGirt, MD, and Clinton Devin, MD Investigation performed at the Department of Orthopaedics & Rehabilitation, Vanderbilt University Medical Center, Nashville, Tennessee
Background: Opioids are commonly used for preoperative pain management in patients undergoing spine surgery. The objective of this investigation was to assess whether preoperative opioid use predicts worse self-reported outcomes in patients undergoing spine surgery. Methods: Five hundred and eighty-three patients undergoing lumbar, thoracolumbar, or cervical spine surgery to treat a structural lesion were included in this prospective cohort study. Self-reported preoperative opioid consumption data were obtained at the preoperative visit and were converted to the corresponding daily morphine equivalent amount. Patient-reported outcome measures were assessed at three and twelve months postoperatively via the 12-Item Short-Form Health Survey and the EuroQol-5D questionnaire, as well as, when appropriate, the Oswestry Disability Index and the Neck Disability Index. Separate multivariable linear regression analyses were then performed. Results: At the preoperative evaluation, of the 583 patients, 56% (326 patients) reported some degree of opioid use. Multivariable analyses controlling for age, sex, diabetes, smoking, surgery invasiveness, revision surgery, preoperative Modified Somatic Perception Questionnaire score, preoperative Zung Depression Scale score, and baseline outcome score found that increased preoperative opioid use was a significant predictor (p < 0.05) of decreased 12-Item ShortForm Health Survey and EuroQol-5D scores, as well as of increased Oswestry Disability Index and Neck Disability Index scores at three and twelve months postoperatively. Every 10-mg increase in daily morphine equivalent amount taken preoperatively was associated with a 0.03 decrease in the 12-Item Short-Form Health Survey physical component summary and mental component summary scores, a 0.01 decrease in the EuroQol-5D score, and a 0.5 increase in the Oswestry Disability Index and Neck Disability Index score at twelve months postoperatively. Higher preoperative Modified Somatic Perception Questionnaire and Zung Depression Scale scores were also significant negative predictors (p < 0.05). Conclusions: Increased preoperative opioid consumption, Modified Somatic Perception Questionnaire score, and Zung Depression Scale score prior to undergoing spine surgery predicted worse patient-reported outcomes. This suggests the potential benefit of psychological and opioid screening with a multidisciplinary approach that includes weaning of opioid use in the preoperative period and close opioid monitoring postoperatively. Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.
Peer Review: This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. It was also reviewed by an expert in methodology and statistics. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors.
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
J Bone Joint Surg Am. 2014;96:e89(1-8)
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n 1995, the American Pain Society, in conjunction with the American Society of Anesthesiologists, began a national campaign to address what was perceived as the undertreatment of pain1,2. What followed was the ‘‘Pain as the 5th Vital Sign’’ initiative in the Veterans Affairs system3,4 and new pain management standards by The Joint Commission5. An exponential increase in opioid sales was subsequently observed, with four times more opioids sold to hospitals, pharmacies, and doctors’ offices in 2010 compared with those sold in 19996. Coincident with this trend has been an increase in opioidrelated complications. Concerns over the risk of iatrogenic opioid dependence, hyperalgesia, poor treatment outcome, impaired cognition, and enabling reliance on the health-care system have been brought up by multiple investigators, with no consensus7-11. In one study, there was a >90% increase in the incidence of opioid-related deaths from 1999 to 200212. Former proponents of opioid use in non-malignant pain settings have now expressed reservation over their widespread use and detrimental side effects13. Regardless, opioids continue to be a mainstay of pain management across all patient populations, particularly among those with spine disorders. Patients undergoing spine surgery to treat a structural lesion present with varying degrees of preoperative opioid use. Previous studies show a 33% to 70% prevalence and suggest that opioid use in the preoperative period has a negative impact on spine surgery outcomes14-18. These studies are limited and do not account for differences in opioid consumption among patients. Moreover, there is a paucity of data on the relationship between preoperative opioid use and patient-reported outcomes following spine surgery. In this study, our objective was to investigate whether the amount of preoperative opioid use predicted worse postoperative patient-reported outcomes at three and twelve months following spine surgery. Outcome measures studied include the 12-Item Short-Form Health Survey (SF-12), EuroQol-5D (EQ-5D) score, Oswestry Disability Index, and Neck Disability Index. Materials and Methods Patients
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ll patients undergoing elective spine surgery at our institution are enrolled into a prospective web-based registry. As enrollment in this registry is standard management at our institution, it has institutional review board exemption status. For this prospective cohort study, 593 patients who underwent elective spine surgery performed by one of six surgeons (two of whom [C.D. and M.J.M.] were authors in this study) at our center from October 2010 to June 2012 were initially included. The ten patients who did not undergo a preoperative outpatient evaluation or had incomplete preoperative opioid consumption data were excluded, resulting in 583 patients included in the study. Clinical data were collected on all patients at the time of preoperative evaluation, including demographics, daily opioid use, relevant comorbidities, and socioeconomic information.
Calculation of Preoperative Opioid Use Preoperative opioid use was prospectively assessed at the preoperative clinic visit by questionnaire. Details regarding opioid type, dosage, route, and frequency of administration in a twenty-four-hour period were recorded. The twenty-fourhour morphine equivalent amount was calculated on the basis of accepted con19-21 version ratios .
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TABLE I Baseline Patient Demographic and Clinical Characteristics of the Study Population Characteristic
Values
Age* (yr)
57.0 ± 13.2
Sex† Female Male
317 (54%) 266 (46%)
Race† White Non-white
512 (88%) 71 (12%)
Insurance† Public Private
291 (50%) 292 (50%)
Smoking history† Never Current Former
273 (47%) 155 (27%) 155 (27%)
Diabetes† No Yes
456 (78%) 127 (22%)
Body mass index category† Normal Overweight Obese
104 (18%) 251 (43%) 228 (39%)
Zung Depression Scale score* (points) Modified Somatic Perception Questionnaire score* (points) Primary versus revision surgery† Primary Revision Type of surgery† Lumbar microdiscectomy Lumbar laminectomy Lumbar fusion Surgery to treat deformity, cancer, or infection Anterior cervical Posterior cervical or anterior and posterior cervical
37.9 ± 9.8 7.6 ± 5.1
381 (65%) 202 (35%) 59 (10%) 86 (15%) 203 (35%) 67 (11%) 101 (17%) 67 (11%)
*The values are given as the mean and the standard deviation. †The values are given as the number of patients, with the percentage in parentheses.
Patient-Reported Outcome Measures The SF-12, EQ-5D, Oswestry Disability Index, and Neck Disability Index scores were obtained prospectively by questionnaire at the preoperative, three-month postoperative, and twelve-month postoperative time points. The Oswestry Disability Index and Neck Disability Index scores were obtained appropriately, depending on whether the lesion was in the lumbar or cervical spine. The SF-12 questionnaire, derived from the SF-36 form, is a twelve-question survey in the 22 Likert format . Results are subdivided into physical component summary (SF-12
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TABLE II Comparison of Preoperative and Postoperative Scores for Patient-Reported Outcomes* Outcome
Preoperative†
Three-Month Postoperative†
Twelve-Month Postoperative†
SF-12 PCS
29.2 ± 9.6 (28.5)
39.6 ± 11.4 (39.9)
39.0 ± 13.2 (39.3)
SF-12 MCS
46.3 ± 12.5 (47.5)
51.6 ± 10.7 (54.1)
49.8 ± 12.2 (53.8)
Oswestry Disability Index and Neck Disability Index
49.2 ± 18.0 (49)
28.7 ± 19.6 (26)
28.4 ± 20.9 (26)
EQ-5D
0.54 ± 0.21 (0.59)
0.75 ± 0.22 (0.81)
0.73 ± 0.22 (0.78)
*Preoperative and postoperative comparisons were significant at p < 0.001. †The values are given as the mean and the standard deviation in points, with the median in parentheses.
PCS) and mental component summary (SF-12 MCS) scores, which range from 0 to 100 points, with higher scores indicating higher levels of health. Similarly, the EQ-5D questionnaire evaluates mobility, self-care, daily activities, pain or discom23,24 fort, and anxiety or depression as they relate to utility and cost-effectiveness . Scores range from 0, representing death, to 1, representing full health. For disability relating to low back and neck pain, Oswestry Disability Index and Neck Disability Index scores range from 0 to 100 points, with values of >40 points 25-27 indicating severe disability . These outcome metrics have been used in general 24-28 and spine-specific patient populations .
Modified Somatic Perception Questionnaire score, preoperative Zung Depression Scale score, and preoperative (baseline) outcome (SF-12 PCS, SF-12 MCS, EQ-5D, or Oswestry Disability Index and Neck Disability Index) score. Tobacco smoking status was categorized as current smoker or nonsmoker. Revision surgery status was determined by previous surgery at or adjacent to the intended operative level. The covariate representing surgery invasiveness was created by grouping specific spine procedures with those of similar invasiveness as determined by the senior author (C.D.). The resultant categories, in order of increasing invasiveness, were as follows: Level 0 (microdiscectomy), Level 1 (lumbar laminectomy and anterior cervical spine), Level 2 (lumbar arthrodesis of three or fewer levels and posterior cervical spine), and Level 3 (deformity, combined anterior and posterior cervical spine, cancer, and infection). The 29 Modified Somatic Perception Questionnaire score was obtained preoperatively via questionnaire to assess the degree to which somatic symptoms are
Predictors and Additional Covariates Demographic and clinical data were prospectively obtained during registry enrollment (Table I). Data included age, sex, race, history of diabetes mellitus, tobacco smoking status, surgery invasiveness, revision surgery status, preoperative
TABLE III Multivariable Linear Regression Models of SF-12 PCS and MCS Scores at Three and Twelve Months Postoperatively SF-12 PCS Score* Variable Preoperative SF-12 score Preoperative opioid use
At Three Months 0.25 (0.14 to 0.35)† 20.03 (20.05 to 20.01)†
SF-12 MCS Score*
At Twelve Months 0.29 (0.18 to 0.40)† 20.03 (20.05 to 20.01)†
At Three Months 0.22 (0.13 to 0.31)† 20.03 (20.05 to 20.01)†
At Twelve Months 0.21 (0.12 to 0.31)† 20.03 (20.05 to 20.01)†
0.16 (21.72 to 2.05)
0.20 (21.88 to 2.29)
20.21 (21.86 to 1.44)
0.01 (21.90 to 1.91)
20.68 (23.39 to 2.02)
21.30 (24.43 to 1.83)
1.71 (21.07 to 4.49)
20.16 (23.00 to 2.67)
21.42 (24.09 to 1.25)
21.45 (24.58 to 1.68)
0.68 (22.06 to 3.41)
20.84 (23.75 to 2.07)
20.68 (24.14 to 2.77)
21.45 (25.22 to 2.32)
1.00 (22.14 to 4.15)
2.15 (21.43 to 5.74)
Age in years
20.14 (20.21 to 20.07)†
20.14 (20.21 to 20.07)†
0.01 (20.04 to 0.07)
0.01 (20.05 to 0.08)
Male versus female (reference)
20.79 (22.50 to 0.92)
0.12 (21.46 to 1.69)
20.38 (22.14 to 1.38)
Revision surgery Surgery invasiveness Level 1 versus level 0 (reference) Level 2 versus level 0 (reference) Level 3 versus level 0 (reference)
0.20 (21.72 to 2.13)
Diabetes
20.97 (23.05 to 1.10)
21.74 (23.98 to 0.50)
1.01 (20.84 to 2.86)
21.09 (23.21 to 1.04)
Current smoker
21.96 (23.94 to 0.01)
20.43 (22.76 to 1.89)
21.12 (23.07 to 0.82)
21.86 (23.92 to 0.20)
Preoperative Modified Somatic Perception Questionnaire score
20.45 (20.65 to 20.25)†
20.79 (21.06 to 20.52)†
20.28 (20.50 to 20.05)†
20.29 (20.54 to 20.05)†
Preoperative Zung Depression Scale score
20.10 (20.20 to 0.01)
20.06 (20.18 to 0.07)
20.10 (20.23 to 0.03)
20.23 (20.37 to 20.10)†
Coefficient of determination
0.22
0.25
0.23
*The value is given as the beta, with the 95% confidence interval in parentheses. †These values were significant at p < 0.05.
0.26
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Fig. 1
Histogram of preoperative twenty-four-hour morphine equivalent amount (MEA) for the study cohort. The values of the MEA are given in milligrams.
associated with psychological responses (somatic anxiety). The Zung Depres30,31 sion Scale score was obtained preoperatively via questionnaire to assess baseline depression. Higher Modified Somatic Perception Questionnaire scores reflect more severe general somatic symptoms and higher Zung Depression Scale scores reflect more severe depression.
Statistical Analysis The primary exposure variable in the analyses was the preoperative daily morphine equivalent amount. The Oswestry Disability Index and Neck Disability Index scores were combined into a single outcome variable to include both the group of patients undergoing cervical spine surgery and the group of patients undergoing lumbar spine surgery in simultaneous analyses. Descriptive statistics were used to summarize all study variables (means, medians, standard deviations, frequency, and skewness). Continuous outcome variables and preoperative daily morphine equivalent amount were examined for the assumptions required for parametric analyses as well as for leverage, influence, and residuals of the observations. Differences in SF-12, EQ-5D, and Oswestry Disability Index and Neck Disability Index scores from preoperative to follow-up time points were analyzed with use of Mann-Whitney U tests. Bivariate linear regression analyses were conducted to assess the association between demographic and clinical variables and SF-12, EQ-5D, and Oswestry Disability Index and Neck Disability Index scores at the three and twelve-month follow-ups. Variables that were significant at p < 0.05 in bivariate analysis or that were considered relevant to the patient-reported outcomes from a clinical perspective were entered into robust multivariable linear regression models for analysis. Analyses for three and twelve-month outcomes were performed separately and all models were controlled for preoperative SF-12, EQ-5D, or Oswestry Disability Index and Neck Disability Index scores, depending on outcome of interest. A priori variables included age, sex, history of diabetes mellitus, tobacco smoking status, surgery invasiveness, revision surgery status, and preoperative Modified Somatic Perception Questionnaire and Zung Depression Scale scores. Multicollinearity was explored post-regression with the variance inflation factor. A random effect for clustering of patients by surgeon was examined, but was removed from final analyses on the basis of limited contribution to the variance of the models. The level of significance was set at p < 0.05. The number of study participants for this study was based on a sample 32,33 size calculation for multiple linear regression . The estimate was based on
the multiple correlation coefficients that are obtained when the controlled a priori independent variables are included in the regression model (R2, C) and only the independent variable of interest is included in the regression model (R2, TjC). Using a conservative R2(C) of 0.05 and an (R2, TjC) of 0.05, an a level of 0.05, and a power of 0.90 and controlling for nine independent variables, a sample size of at least 192 was needed to detect an association between the preoperative daily morphine equivalent amount and patient-reported postoperative outcomes using multivariable linear regression analyses.
Source of Funding There was no external source of funding.
Results Cohort Characteristics f the 583 patients who underwent elective surgery to treat a structural lesion and were included in the final analysis, 350 (60%) underwent lumbar surgery, sixty-four (11%) underwent thoracolumbar surgery, and 169 (29%) underwent cervical spine surgery. The median preoperative daily morphine equivalent amount for the cohort was 8.75 mg (interquartile range, 0 to 37.5 mg), with 56% (326 patients) reporting some degree of preoperative opioid use. The twenty-four-hour (daily) distribution of the preoperative morphine equivalent amount for the cohort is presented in a histogram form in Figure 1.
O
Patient-Reported Outcomes With Mann-Whitney U tests, the SF-12 PCS and MCS scores were significantly improved (p < 0.001) at both the three and twelve-month follow-ups, as were the Oswestry Disability Index and Neck Disability Index scores and the EQ-5D scores (Table II). Significant differences between three and twelve months of followup were noted for the SF-12 MCS (p = 0.001) and EQ-5D (p = 0.03) scores.
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TABLE IV Multivariable Linear Regression Models of Oswestry Disability Index and Neck Disability Index Scores and EQ-5D Scores at Three and Twelve Months Postoperatively Oswestry Disability Index and Neck Disability Index Scores* Variable
At Three Months
EQ-5D Scores*
At Twelve Months
At Three Months 0.07 (20.03 to 0.18)
At Twelve Months
Preoperative outcome score
0.25 (0.16 to 0.34)†
0.19 (0.09 to 0.29)†
Preoperative opioid use
0.06 (0.03 to 0.10)†
0.05 (0.02 to 0.09)†
Revision surgery
0.45 (22.57 to 3.46)
20.48 (23.55 to 2.59)
Level 1 versus level 0 (reference)
0.43 (24.34 to 5.19)
3.47 (21.18 to 8.12)
Level 2 versus level 0 (reference) Level 3 versus level 0 (reference)
0.77 (23.85 to 5.40)
3.07 (21.51 to 7.65)
20.02 (20.08 to 0.04)
20.04 (20.08 to 0.01)
20.41 (26.27 to 5.46)
0.90 (24.57 to 6.38)
20.01 (20.08 to 0.07)
20.02 (20.08 to 0.04)
0.28 (0.18 to 0.39)
0.23 (0.13 to 0.33)
20.001 (20.002 to 0.000)
20.001 (20.002 to 0.000)
21.42 (24.22 to 1.39)
20.47 (23.30 to 2.35)
20.01 (20.05 to 0.02)
20.02 (20.05 to 0.01)
20.001 (20.001 to 20.000)‡ 0.01 (20.03 to 0.05)
0.08 (20.01 to 0.17) 20.001 (20.001 to 20.000)‡ 0.02 (20.01 to 0.06)
Surgery invasiveness
Age in years Male versus female (reference)
0.001 (20.059 to 0.060)
20.02 (20.07 to 0.03)
Diabetes
2.82 (20.47 to 6.10)
4.63 (1.20 to 8.06)†
0.02 (20.02 to 0.05)
20.03 (20.07 to 0.01)
Current smoker
4.03 (0.84 to 7.22)†
3.24 (20.15 to 6.62)
20.03 (20.07 to 0.01)
20.03 (20.07 to 0.01)
Preoperative Modified Somatic Perception Questionnaire score
0.77 (0.42 to 1.13)†
1.21 (0.80 to 1.62)†
20.01 (20.01 to 0.00)‡
20.02 (20.2 to 20.01)‡
Preoperative Zung Depression Scale score
0.17 (20.30 to 0.37)
0.28 (0.08 to 0.49)†
20.004 (20.007 to 20.001)‡
20.004 (20.007 to 20.002)‡
0.17
0.29
Coefficient of determination
0.30
0.33
*The values are given as the beta, with the 95% confidence interval in parentheses. †These values were significant at p < 0.001. ‡These values were significant at p < 0.05.
Multivariable Models of SF-12 PCS and MCS Scores, Combined Oswestry Disability Index and Neck Disability Index Score, and EQ-5D Score Separate robust multivariable analyses demonstrated that increased preoperative opioid use was a significant predictor (p < 0.05) of decreased SF-12 PCS and MCS scores at three and twelve months postoperatively (Table III). Every 10-mg increase in the morphine equivalent amount taken preoperatively in a twentyfour-hour period predicted a 0.3 decrease in SF-12 PCS and MCS scores at three and twelve months postoperatively. Other significant predictors (p < 0.05) of decreased SF-12 PCS scores at three and twelve months postoperatively included preoperative SF-12 PCS score, age, and preoperative Modified Somatic Perception Questionnaire score. Preoperative SF-12 MCS and Modified Somatic Perception Questionnaire scores were also significant predictors (p < 0.05) of decreased SF-12 MCS scores at three and twelve months. The preoperative Zung Depression Scale score was only a significant predictor (p < 0.05) at twelve months postoperatively. Preoperative opioid use was also found to be a significant predictor (p < 0.001) of increased postoperative Oswestry Disability Index and Neck Disability Index scores at three and twelve months postoperatively (Table IV). Specifically, in the Oswestry Disability Index and Neck Disability Index score, every 10-mg increase in the morphine equivalent amount taken preoperatively
in a twenty-four-hour period predicted a 0.6 increase at three months and a 0.5 increase at twelve months. The preoperative Oswestry Disability Index and Neck Disability Index and the Modified Somatic Perception Questionnaire scores were also significant predictors (p < 0.001) of increased Oswestry Disability Index and Neck Disability Index scores at three and twelve months postoperatively. Smoking was a significant predictor (p < 0.001) at three months postoperatively only, while diabetes and preoperative Zung Depression Scale score were significant predictors (p < 0.001) at twelve months postoperatively only. Preoperative opioid use was a significant predictor (p < 0.05) of decreased EQ-5D scores at three and twelve months postoperatively (Table IV). Specifically, every 10-mg increase in morphine equivalent amount taken preoperatively in a twenty-four-hour period predicted a 0.01 decrease in the EQ-5D score at three and twelve months postoperatively. Other significant predictors (p < 0.05) of decreased EQ-5D scores at three and twelve months postoperatively included preoperative Modified Somatic Perception Questionnaire and Zung Depression Scale scores. Discussion ithin the context of growing national concern over the deleterious effects of physician-prescribed opioids, we examined whether increased opioid use in the preoperative period
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predicted worse patient-reported outcomes following elective spine surgery. The 56% prevalence of preoperative opioid use in our cohort is similar to that shown in other studies14-18. We demonstrated that after controlling for multiple demographic and clinical variables, increased preoperative opioid use was a significant predictor of adverse patient-reported outcomes. Previous work has examined preoperative opioid use as a predictor of clinical outcome after spine surgery. J¨onsson found that regular consumption of analgesics preoperatively was associated with increased postoperative pain in patients with central lumbar spinal stenosis17. However, no details were provided as to the type of analgesics used preoperatively. A recent reanalysis of the Spine Patient Outcomes Research Trial (SPORT) cohort aimed at identifying treatment effect predictors found that preoperative opioid use did have a significant treatment effect after minimally adjusted analyses, but significance did not carry over into subsequent multivariable analysis18. Studies that have further examined preoperative opioid use as a potential predictor of outcome are limited by their treatment of opioid use as a categorical (as opposed to a continuous) variable. In a retrospective cohort study of 488 patients undergoing anterior cervical discectomy and fusion, Anderson et al. identified weak opioid use as a potential negative predictor for clinical success from a multivariable model of several prognostic factors, but subsequent stepwise regression analysis did not demonstrate significance16. Their cohort reported a 70% prevalence of preoperative opioid use, which was subsequently dichotomized into weak and strong use. Clinical success was defined as a Neck Disability Index improvement of >15 points, maintained or improved neurologic examination, no adverse events, and no revision surgery. No definition on the weak or strong designation of opioids was provided. Lawrence et al.14 examined ninety-one patients undergoing anterior cervical discectomy and fusion and separated them into two groups based on whether they required daily opioids for at least six months preoperatively or not. That single-surgeon cohort demonstrated a 52% prevalence of opioid use. There was also a significantly lower incidence of good or excellent results following surgery for those requiring opioids (51%) compared with those not requiring opioids (86%). There was a significantly higher incidence of poor results in the opioid group (32%) compared with the non-opioid group (0%)14. Clinical outcome was based on pain assessment, medication use, activity level, and work status. Analysis in that study did not control for other possible significant variables. Currently, to our knowledge, no validated stratification system of preoperative opioid use in the population undergoing elective spine surgery exists. Subgroups have been proposed on the basis of expert opinion, as by the Productive Rehabilitation Institute of Dallas for Ergonomics (PRIDE) Research Foundation for patients with chronic spinal disorders. On the basis of the daily morphine equivalent amount, patients who reported opioid use were divided into subgroups of low (£30 mg), medium (31 to 60 mg), high (61 to 120 mg), and very high (>120 mg)34. Knowledge that increased preoperative opioid use negatively predicts outcome may provide motivation to both patient
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and surgeon to decrease or to eliminate opioid use prior to surgery. The amount of opioid consumption that actually leads to a clinically relevant difference in these outcomes remains unknown. The minimal clinically important difference of patientreported outcomes in various populations undergoing spine surgery has been proposed by other investigators35-41. These values stem from populations undergoing specific spine surgery and are not globally applicable to our cohort, which is inclusive of all elective spine cases. For example, the range of the minimal clinically important difference for the SF-12 PCS score is 7.0 to 12.239 in patients undergoing primary anterior cervical discectomy and fusion, compared with 3.2 to 6.1 for patients undergoing revision surgery for symptomatic lumbar pseudarthrosis38. Increased preoperative Modified Somatic Perception Questionnaire score was a significant predictor (p < 0.05) for worse patient-reported outcomes. Early work has already linked somatization and other psychological factors with poorer outcomes in various surgical spine cohorts42-45. Main et al. proposed the Distress and Risk Assessment Method (DRAM) as a tool to predict outcome in patients with low back pain46. This method incorporates the Zung Depression Scale and Modified Somatic Perception Questionnaire scores to stratify patients as normal, at risk, or distressed. However, follow-up studies demonstrated that the DRAM did not predict disability outcome in patients undergoing lumbar surgery47,48. More recently, Chaichana et al. demonstrated that an increased Modified Somatic Perception Questionnaire score was associated with a decreased likelihood of achieving a minimal clinically important difference in the SF-36 and Oswestry Disability Index scores following lumbar discectomy49. Although the benefit of screening tools such as the DRAM remains to be validated, our results support the consideration of somatization or anxiety in the preoperative period. The strengths of our study included a large sample size, prospective design, inclusiveness of all elective spine cases, use of multivariable analyses, and treatment of preoperative opioid use as a continuous variable. Although larger than previous studies, our single-center study still describes a relatively small sample size. The inclusion of all types of elective spine surgical procedures may be a confounding variable. We attempted to account for this with the introduction of a categorical covariate that groups procedures of like invasiveness. Groupings were formed on the basis of the experience of the senior author (C.D.) and have not been validated. Our analyses also did not account for duration of preoperative opioid use. Use of state registries that track opioid prescriptions filled for a patient may provide a more accurate reflection of opioid use. Importantly, we also did not track continued opioid use at the three and twelve-month postoperative visits, and this represents a flaw in our study design. It is possible that opioid use in the postoperative period may have an impact on patient-reported outcomes to a greater degree than preoperative opioid use. The fact that our subsequent models did not include postoperative opioid use as a covariate was a limitation to our study. Despite these limitations, our work represents a timely investigation into whether preoperative opioid use has a negative
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impact on spine surgery outcomes. Additional prospective data comparing the outcomes of patients who successfully decrease their opioid intake prior to surgery, and those who do not, would provide more definitive evidence on the impact of preoperative opioid use on patient-reported outcomes. Subsequent work should also assess the impact of additional interventions, such as psychiatric screening, counseling, and therapy in the preoperative period, as well as close opioid monitoring postoperatively. n
David Shau, BS Harrison Kay, BS Chi Zhang, BA Clinton Devin, MD Department of Orthopaedics & Rehabilitation, Vanderbilt University Medical Center, 1215 21st Avenue South, Medical Center East, South Tower, Suite 4200, Nashville, TN 37232. E-mail address for D. Lee: [email protected]. E-mail address for C. Devin: [email protected]
Dennis Lee, MD Sheyan Armaghani, MD Kristin R. Archer, PhD, DPT Jesse Bible, MD
Matthew J. McGirt, MD Carolina Neurosurgery & Spine Associates, 225 Baldwin Avenue, Charlotte, NC 28204
References 1. American Pain Society Quality of Care Committee. Quality improvement guidelines for the treatment of acute pain and cancer pain. JAMA. 1995 Dec 20;274(23): 1874-80. 2. Practice guidelines for acute pain management in the perioperative setting. A report by the American Society of Anesthesiologists Task Force on Pain Management, Acute Pain Section. Anesthesiology. 1995 Apr;82(4):1071-81. 3. Veterans Health Administration National Pain Management Strategy. 1998 Nov 12. 4. 1999 Veterans Health Administration Memorandum. Pain as the fifth vital sign. 1999 Mar 1. 5. Joint Commission on Accreditation of Healthcare Organizations. Pain management standards. 2000. http://www.jointcomission.org/standards_information/ standards.aspx. Accessed 2013 Jan 24. 6. Okie S. A flood of opioids, a rising tide of deaths. N Engl J Med. 2010 Nov 18; 363(21):1981-5. 7. Benyamin R, Trescot AM, Datta S, Buenaventura R, Adlaka R, Sehgal N, Glaser SE, Vallejo R. Opioid complications and side effects. Pain Physician. 2008 Mar; 11(2)(Suppl):S105-20. 8. Schofferman J. Long-term use of opioid analgesics for the treatment of chronic pain of nonmalignant origin. J Pain Symptom Manage. 1993 Jul;8(5):279-88. 9. Schofferman J. Long-term opioid analgesic therapy for severe refractory lumbar spine pain. Clin J Pain. 1999 Jun;15(2):136-40. 10. Bartleson JD. Evidence for and against the use of opioid analgesics for chronic nonmalignant low back pain: a review. Pain Med. 2002 Sep;3(3):260-71. 11. Jamison RN, Raymond SA, Slawsby EA, Nedeljkovic SS, Katz NP. Opioid therapy for chronic noncancer back pain. A randomized prospective study. Spine (Phila Pa 1976). 1998 Dec 1;23(23):2591-600. 12. Paulozzi LJ, Budnitz DS, Xi Y. Increasing deaths from opioid analgesics in the United States. Pharmacoepidemiol Drug Saf. 2006 Sep;15(9):618-27. 13. Catan T, Perez E. A pain-drug champion has second thoughts. The Wall Street Journal. 2012 Dec 17. http://online.wsj.com/news/articles/ SB10001424127887324478304578173342657044604. Accessed 2014 Jan 14. 14. Lawrence JT, London N, Bohlman HH, Chin KR. Preoperative narcotic use as a predictor of clinical outcome: results following anterior cervical arthrodesis. Spine (Phila Pa 1976). 2008 Sep 1;33(19):2074-8. 15. Aalto TJ, Malmivaara A, Kovacs F, Herno A, Alen M, Salmi L, Kr¨oger H, Andrade J, Jim´enez R, Tapaninaho A, Turunen V, Savolainen S, Airaksinen O. Preoperative predictors for postoperative clinical outcome in lumbar spinal stenosis: systematic review. Spine (Phila Pa 1976). 2006 Aug 15;31(18):E648-63. 16. Anderson PA, Subach BR, Riew KD. Predictors of outcome after anterior cervical discectomy and fusion: a multivariate analysis. Spine (Phila Pa 1976). 2009 Jan 15;34(2):161-6. 17. J¨onsson B. Patient-related factors predicting the outcome of decompressive surgery. Acta Orthop Scand Suppl. 1993;251:69-70. 18. Pearson A, Lurie J, Tosteson T, Zhao W, Abdu W, Weinstein JN. Who should have surgery for spinal stenosis? Treatment effect predictors in SPORT. Spine (Phila Pa 1976). 2012 Oct 1;37(21):1791-802. 19. Donner B, Zenz M, Tryba M, Strumpf M. Direct conversion from oral morphine to transdermal fentanyl: a multicenter study in patients with cancer pain. Pain. 1996 Mar;64(3):527-34. 20. Pereira J, Lawlor P, Vigano A, Dorgan M, Bruera E. Equianalgesic dose ratios for opioids. a critical review and proposals for long-term dosing. J Pain Symptom Manage. 2001 Aug;22(2):672-87.
21. Periyakoil V. End of Life Curriculum Project. Joint project of the United States Veterans Administration and Stanford University Medical School. 2012. http:// endoflife.stanford.edu. Accessed 2012 Nov 1. 22. Ware J Jr, Kosinski M, Keller SD. A 12-Item Short-Form Health Survey: construction of scales and preliminary tests of reliability and validity. Med Care. 1996 Mar;34(3): 220-33. 23. Brooks R. EuroQol: the current state of play. Health Policy. 1996 Jul;37(1): 53-72. ˚ N´emeth G, Granath F, J¨onsson B, Blomqvist P. Health-related 24. Jansson KA, quality of life (EQ-5D) before and one year after surgery for lumbar spinal stenosis. J Bone Joint Surg Br. 2009 Feb;91(2):210-6. 25. Fairbank JC, Couper J, Davies JB, O’Brien JP. The Oswestry low back pain disability questionnaire. Physiotherapy. 1980 Aug;66(8):271-3. 26. Fairbank JC, Pynsent PB. The Oswestry Disability Index. Spine (Phila Pa 1976). 2000 Nov 15;25(22):2940-52, discussion: 2952. 27. Richardson SS, Berven S. The development of a model for translation of the Neck Disability Index to utility scores for cost-utility analysis in cervical disorders. Spine J. 2012 Jan;12(1):55-62. Epub 2011 Dec 29. 28. Ware JE Jr. SF-36 health survey update. Spine (Phila Pa 1976). 2000 Dec 15; 25(24):3130-9. 29. Main CJ. The Modified Somatic Perception Questionnaire (MSPQ). J Psychosom Res. 1983;27(6):503-14. 30. Thurber S, Snow M, Honts CR. The Zung Self-Rating Depression Scale: convergent validity and diagnostic discrimination. Assessment. 2002 Dec;9(4): 401-5. 31. Zung WW, Richards CB, Short MJ. Self-rating depression scale in an outpatient clinic. Further validation of the SDS. Arch Gen Psychiatry. 1965 Dec;13(6): 508-15. 32. Cohen J. Statistical power analysis for the behavioral sciences. 2nd ed. Hillsdale, NJ: Lawrence Erlbaum; 1988. 33. Hintze JL. PASS 6.0 user’s guide. Kaysville: Number Cruncher Statistical Systems;1996. 34. Kidner CL, Gatchel RJ, Mayer TG. MMPI disability profile is associated with degree of opioid use in chronic work-related musculoskeletal disorders. Clin J Pain. 2010 Jan;26(1):9-15. 35. Carreon LY, Bratcher KR, Canan CE, Burke LO, Djurasovic M, Glassman SD. Differentiating minimum clinically important difference for primary and revision lumbar fusion surgeries. J Neurosurg Spine. 2013 Jan;18(1):102-6. Epub 2012 Nov 16. 36. Carreon LY, Glassman SD, Campbell MJ, Anderson PA. Neck Disability Index, short form-36 physical component summary, and pain scales for neck and arm pain: the minimum clinically important difference and substantial clinical benefit after cervical spine fusion. Spine J. 2010 Jun;10(6):469-74. Epub 2010 Apr 1. 37. Copay AG, Glassman SD, Subach BR, Berven S, Schuler TC, Carreon LY. Minimum clinically important difference in lumbar spine surgery patients: a choice of methods using the Oswestry Disability Index, Medical Outcomes Study questionnaire Short Form 36, and pain scales. Spine J. 2008 Nov-Dec;8(6):968-74. Epub 2008 Jan 16. 38. Parker SL, Adogwa O, Mendenhall SK, Shau DN, Anderson WN, Cheng JS, Devin CJ, McGirt MJ. Determination of minimum clinically important difference (MCID) in pain, disability, and quality of life after revision fusion for symptomatic pseudoarthrosis. Spine J. 2012 Dec;12(12):1122-8. Epub 2012 Nov 14.
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39. Parker SL, Godil SS, Shau DN, Mendenhall SK, McGirt MJ. Assessment of the minimum clinically important difference in pain, disability, and quality of life after anterior cervical discectomy and fusion: clinical article. J Neurosurg Spine. 2013 Feb; 18(2):154-60. Epub 2012 Nov 23. 40. Parker SL, Mendenhall SK, Shau D, Adogwa O, Cheng JS, Anderson WN, Devin CJ, McGirt MJ. Determination of minimum clinically important difference in pain, disability, and quality of life after extension of fusion for adjacent-segment disease. J Neurosurg Spine. 2012 Jan;16(1):61-7. Epub 2011 Sep 30. 41. Parker SL, Mendenhall SK, Shau DN, Adogwa O, Anderson WN, Devin CJ, McGirt MJ. Minimum clinically important difference in pain, disability, and quality of life after neural decompression and fusion for same-level recurrent lumbar stenosis: understanding clinical versus statistical significance. J Neurosurg Spine. 2012 May;16(5):471-8. Epub 2012 Feb 10. 42. Dzioba RB, Doxey NC. A prospective investigation into the orthopaedic and psychologic predictors of outcome of first lumbar surgery following industrial injury. Spine (Phila Pa 1976). 1984 Sep;9(6):614-23. 43. Spengler DM, Ouellette EA, Batti´e M, Zeh J. Elective discectomy for herniation of a lumbar disc. Additional experience with an objective method. J Bone Joint Surg Am. 1990 Feb;72(2):230-7.
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44. Wilfling FJ, Klonoff H, Kokan P. Psychological, demographic and orthopaedic factors associated with prediction of outcome of spinal fusion. Clin Orthop Relat Res. 1973 Jan-Feb;(90):153-60. 45. Wiltse LL. Psychological testing in predicting the success of low back surgery. Orthop Clin North Am. 1975 Jan;6(1):317-8. 46. Main CJ, Wood PL, Hollis S, Spanswick CC, Waddell G; The Distress and Risk Assessment Method. The Distress and Risk Assessment Method. A simple patient classification to identify distress and evaluate the risk of poor outcome. Spine (Phila Pa 1976). 1992 Jan;17(1):42-52. 47. Hobby JL, Lutchman LN, Powell JM, Sharp DJ. The distress and risk assessment method (DRAM). J Bone Joint Surg Br. 2001 Jan;83(1):19-21. 48. Tandon V, Campbell F, Ross ER. Posterior lumbar interbody fusion. Association between disability and psychological disturbance in noncompensation patients. Spine (Phila Pa 1976). 1999 Sep 1;24(17):1833-8. 49. Chaichana KL, Mukherjee D, Adogwa O, Cheng JS, McGirt MJ. Correlation of preoperative depression and somatic perception scales with postoperative disability and quality of life after lumbar discectomy. J Neurosurg Spine. 2011 Feb;14(2): 261-7. Epub 2011 Jan 7.
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Preoperative Opioid Use as a Predictor of Adverse Postoperative Self-Reported Outcomes in Patients Undergoing Spine Surgery Dennis Lee, MD, Sheyan Armaghani, MD, Kristin R. Archer, PhD, DPT, Jesse Bible, MD, David Shau, BS, Harrison Kay, BS, Chi Zhang, BA, Matthew J. McGirt, MD, and Clinton Devin, MD Investigation performed at the Department of Orthopaedics & Rehabilitation, Vanderbilt University Medical Center, Nashville, Tennessee
Background: Opioids are commonly used for preoperative pain management in patients undergoing spine surgery. The objective of this investigation was to assess whether preoperative opioid use predicts worse self-reported outcomes in patients undergoing spine surgery. Methods: Five hundred and eighty-three patients undergoing lumbar, thoracolumbar, or cervical spine surgery to treat a structural lesion were included in this prospective cohort study. Self-reported preoperative opioid consumption data were obtained at the preoperative visit and were converted to the corresponding daily morphine equivalent amount. Patient-reported outcome measures were assessed at three and twelve months postoperatively via the 12-Item Short-Form Health Survey and the EuroQol-5D questionnaire, as well as, when appropriate, the Oswestry Disability Index and the Neck Disability Index. Separate multivariable linear regression analyses were then performed. Results: At the preoperative evaluation, of the 583 patients, 56% (326 patients) reported some degree of opioid use. Multivariable analyses controlling for age, sex, diabetes, smoking, surgery invasiveness, revision surgery, preoperative Modified Somatic Perception Questionnaire score, preoperative Zung Depression Scale score, and baseline outcome score found that increased preoperative opioid use was a significant predictor (p < 0.05) of decreased 12-Item ShortForm Health Survey and EuroQol-5D scores, as well as of increased Oswestry Disability Index and Neck Disability Index scores at three and twelve months postoperatively. Every 10-mg increase in daily morphine equivalent amount taken preoperatively was associated with a 0.03 decrease in the 12-Item Short-Form Health Survey physical component summary and mental component summary scores, a 0.01 decrease in the EuroQol-5D score, and a 0.5 increase in the Oswestry Disability Index and Neck Disability Index score at twelve months postoperatively. Higher preoperative Modified Somatic Perception Questionnaire and Zung Depression Scale scores were also significant negative predictors (p < 0.05). Conclusions: Increased preoperative opioid consumption, Modified Somatic Perception Questionnaire score, and Zung Depression Scale score prior to undergoing spine surgery predicted worse patient-reported outcomes. This suggests the potential benefit of psychological and opioid screening with a multidisciplinary approach that includes weaning of opioid use in the preoperative period and close opioid monitoring postoperatively. Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.
Peer Review: This article was reviewed by the Editor-in-Chief and one Deputy Editor, and it underwent blinded review by two or more outside experts. It was also reviewed by an expert in methodology and statistics. The Deputy Editor reviewed each revision of the article, and it underwent a final review by the Editor-in-Chief prior to publication. Final corrections and clarifications occurred during one or more exchanges between the author(s) and copyeditors.
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
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n 1995, the American Pain Society, in conjunction with the American Society of Anesthesiologists, began a national campaign to address what was perceived as the undertreatment of pain1,2. What followed was the ‘‘Pain as the 5th Vital Sign’’ initiative in the Veterans Affairs system3,4 and new pain management standards by The Joint Commission5. An exponential increase in opioid sales was subsequently observed, with four times more opioids sold to hospitals, pharmacies, and doctors’ offices in 2010 compared with those sold in 19996. Coincident with this trend has been an increase in opioidrelated complications. Concerns over the risk of iatrogenic opioid dependence, hyperalgesia, poor treatment outcome, impaired cognition, and enabling reliance on the health-care system have been brought up by multiple investigators, with no consensus7-11. In one study, there was a >90% increase in the incidence of opioid-related deaths from 1999 to 200212. Former proponents of opioid use in non-malignant pain settings have now expressed reservation over their widespread use and detrimental side effects13. Regardless, opioids continue to be a mainstay of pain management across all patient populations, particularly among those with spine disorders. Patients undergoing spine surgery to treat a structural lesion present with varying degrees of preoperative opioid use. Previous studies show a 33% to 70% prevalence and suggest that opioid use in the preoperative period has a negative impact on spine surgery outcomes14-18. These studies are limited and do not account for differences in opioid consumption among patients. Moreover, there is a paucity of data on the relationship between preoperative opioid use and patient-reported outcomes following spine surgery. In this study, our objective was to investigate whether the amount of preoperative opioid use predicted worse postoperative patient-reported outcomes at three and twelve months following spine surgery. Outcome measures studied include the 12-Item Short-Form Health Survey (SF-12), EuroQol-5D (EQ-5D) score, Oswestry Disability Index, and Neck Disability Index. Materials and Methods Patients
A
ll patients undergoing elective spine surgery at our institution are enrolled into a prospective web-based registry. As enrollment in this registry is standard management at our institution, it has institutional review board exemption status. For this prospective cohort study, 593 patients who underwent elective spine surgery performed by one of six surgeons (two of whom [C.D. and M.J.M.] were authors in this study) at our center from October 2010 to June 2012 were initially included. The ten patients who did not undergo a preoperative outpatient evaluation or had incomplete preoperative opioid consumption data were excluded, resulting in 583 patients included in the study. Clinical data were collected on all patients at the time of preoperative evaluation, including demographics, daily opioid use, relevant comorbidities, and socioeconomic information.
Calculation of Preoperative Opioid Use Preoperative opioid use was prospectively assessed at the preoperative clinic visit by questionnaire. Details regarding opioid type, dosage, route, and frequency of administration in a twenty-four-hour period were recorded. The twenty-fourhour morphine equivalent amount was calculated on the basis of accepted con19-21 version ratios .
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TABLE I Baseline Patient Demographic and Clinical Characteristics of the Study Population Characteristic
Values
Age* (yr)
57.0 ± 13.2
Sex† Female Male
317 (54%) 266 (46%)
Race† White Non-white
512 (88%) 71 (12%)
Insurance† Public Private
291 (50%) 292 (50%)
Smoking history† Never Current Former
273 (47%) 155 (27%) 155 (27%)
Diabetes† No Yes
456 (78%) 127 (22%)
Body mass index category† Normal Overweight Obese
104 (18%) 251 (43%) 228 (39%)
Zung Depression Scale score* (points) Modified Somatic Perception Questionnaire score* (points) Primary versus revision surgery† Primary Revision Type of surgery† Lumbar microdiscectomy Lumbar laminectomy Lumbar fusion Surgery to treat deformity, cancer, or infection Anterior cervical Posterior cervical or anterior and posterior cervical
37.9 ± 9.8 7.6 ± 5.1
381 (65%) 202 (35%) 59 (10%) 86 (15%) 203 (35%) 67 (11%) 101 (17%) 67 (11%)
*The values are given as the mean and the standard deviation. †The values are given as the number of patients, with the percentage in parentheses.
Patient-Reported Outcome Measures The SF-12, EQ-5D, Oswestry Disability Index, and Neck Disability Index scores were obtained prospectively by questionnaire at the preoperative, three-month postoperative, and twelve-month postoperative time points. The Oswestry Disability Index and Neck Disability Index scores were obtained appropriately, depending on whether the lesion was in the lumbar or cervical spine. The SF-12 questionnaire, derived from the SF-36 form, is a twelve-question survey in the 22 Likert format . Results are subdivided into physical component summary (SF-12
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TABLE II Comparison of Preoperative and Postoperative Scores for Patient-Reported Outcomes* Outcome
Preoperative†
Three-Month Postoperative†
Twelve-Month Postoperative†
SF-12 PCS
29.2 ± 9.6 (28.5)
39.6 ± 11.4 (39.9)
39.0 ± 13.2 (39.3)
SF-12 MCS
46.3 ± 12.5 (47.5)
51.6 ± 10.7 (54.1)
49.8 ± 12.2 (53.8)
Oswestry Disability Index and Neck Disability Index
49.2 ± 18.0 (49)
28.7 ± 19.6 (26)
28.4 ± 20.9 (26)
EQ-5D
0.54 ± 0.21 (0.59)
0.75 ± 0.22 (0.81)
0.73 ± 0.22 (0.78)
*Preoperative and postoperative comparisons were significant at p < 0.001. †The values are given as the mean and the standard deviation in points, with the median in parentheses.
PCS) and mental component summary (SF-12 MCS) scores, which range from 0 to 100 points, with higher scores indicating higher levels of health. Similarly, the EQ-5D questionnaire evaluates mobility, self-care, daily activities, pain or discom23,24 fort, and anxiety or depression as they relate to utility and cost-effectiveness . Scores range from 0, representing death, to 1, representing full health. For disability relating to low back and neck pain, Oswestry Disability Index and Neck Disability Index scores range from 0 to 100 points, with values of >40 points 25-27 indicating severe disability . These outcome metrics have been used in general 24-28 and spine-specific patient populations .
Modified Somatic Perception Questionnaire score, preoperative Zung Depression Scale score, and preoperative (baseline) outcome (SF-12 PCS, SF-12 MCS, EQ-5D, or Oswestry Disability Index and Neck Disability Index) score. Tobacco smoking status was categorized as current smoker or nonsmoker. Revision surgery status was determined by previous surgery at or adjacent to the intended operative level. The covariate representing surgery invasiveness was created by grouping specific spine procedures with those of similar invasiveness as determined by the senior author (C.D.). The resultant categories, in order of increasing invasiveness, were as follows: Level 0 (microdiscectomy), Level 1 (lumbar laminectomy and anterior cervical spine), Level 2 (lumbar arthrodesis of three or fewer levels and posterior cervical spine), and Level 3 (deformity, combined anterior and posterior cervical spine, cancer, and infection). The 29 Modified Somatic Perception Questionnaire score was obtained preoperatively via questionnaire to assess the degree to which somatic symptoms are
Predictors and Additional Covariates Demographic and clinical data were prospectively obtained during registry enrollment (Table I). Data included age, sex, race, history of diabetes mellitus, tobacco smoking status, surgery invasiveness, revision surgery status, preoperative
TABLE III Multivariable Linear Regression Models of SF-12 PCS and MCS Scores at Three and Twelve Months Postoperatively SF-12 PCS Score* Variable Preoperative SF-12 score Preoperative opioid use
At Three Months 0.25 (0.14 to 0.35)† 20.03 (20.05 to 20.01)†
SF-12 MCS Score*
At Twelve Months 0.29 (0.18 to 0.40)† 20.03 (20.05 to 20.01)†
At Three Months 0.22 (0.13 to 0.31)† 20.03 (20.05 to 20.01)†
At Twelve Months 0.21 (0.12 to 0.31)† 20.03 (20.05 to 20.01)†
0.16 (21.72 to 2.05)
0.20 (21.88 to 2.29)
20.21 (21.86 to 1.44)
0.01 (21.90 to 1.91)
20.68 (23.39 to 2.02)
21.30 (24.43 to 1.83)
1.71 (21.07 to 4.49)
20.16 (23.00 to 2.67)
21.42 (24.09 to 1.25)
21.45 (24.58 to 1.68)
0.68 (22.06 to 3.41)
20.84 (23.75 to 2.07)
20.68 (24.14 to 2.77)
21.45 (25.22 to 2.32)
1.00 (22.14 to 4.15)
2.15 (21.43 to 5.74)
Age in years
20.14 (20.21 to 20.07)†
20.14 (20.21 to 20.07)†
0.01 (20.04 to 0.07)
0.01 (20.05 to 0.08)
Male versus female (reference)
20.79 (22.50 to 0.92)
0.12 (21.46 to 1.69)
20.38 (22.14 to 1.38)
Revision surgery Surgery invasiveness Level 1 versus level 0 (reference) Level 2 versus level 0 (reference) Level 3 versus level 0 (reference)
0.20 (21.72 to 2.13)
Diabetes
20.97 (23.05 to 1.10)
21.74 (23.98 to 0.50)
1.01 (20.84 to 2.86)
21.09 (23.21 to 1.04)
Current smoker
21.96 (23.94 to 0.01)
20.43 (22.76 to 1.89)
21.12 (23.07 to 0.82)
21.86 (23.92 to 0.20)
Preoperative Modified Somatic Perception Questionnaire score
20.45 (20.65 to 20.25)†
20.79 (21.06 to 20.52)†
20.28 (20.50 to 20.05)†
20.29 (20.54 to 20.05)†
Preoperative Zung Depression Scale score
20.10 (20.20 to 0.01)
20.06 (20.18 to 0.07)
20.10 (20.23 to 0.03)
20.23 (20.37 to 20.10)†
Coefficient of determination
0.22
0.25
0.23
*The value is given as the beta, with the 95% confidence interval in parentheses. †These values were significant at p < 0.05.
0.26
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Fig. 1
Histogram of preoperative twenty-four-hour morphine equivalent amount (MEA) for the study cohort. The values of the MEA are given in milligrams.
associated with psychological responses (somatic anxiety). The Zung Depres30,31 sion Scale score was obtained preoperatively via questionnaire to assess baseline depression. Higher Modified Somatic Perception Questionnaire scores reflect more severe general somatic symptoms and higher Zung Depression Scale scores reflect more severe depression.
Statistical Analysis The primary exposure variable in the analyses was the preoperative daily morphine equivalent amount. The Oswestry Disability Index and Neck Disability Index scores were combined into a single outcome variable to include both the group of patients undergoing cervical spine surgery and the group of patients undergoing lumbar spine surgery in simultaneous analyses. Descriptive statistics were used to summarize all study variables (means, medians, standard deviations, frequency, and skewness). Continuous outcome variables and preoperative daily morphine equivalent amount were examined for the assumptions required for parametric analyses as well as for leverage, influence, and residuals of the observations. Differences in SF-12, EQ-5D, and Oswestry Disability Index and Neck Disability Index scores from preoperative to follow-up time points were analyzed with use of Mann-Whitney U tests. Bivariate linear regression analyses were conducted to assess the association between demographic and clinical variables and SF-12, EQ-5D, and Oswestry Disability Index and Neck Disability Index scores at the three and twelve-month follow-ups. Variables that were significant at p < 0.05 in bivariate analysis or that were considered relevant to the patient-reported outcomes from a clinical perspective were entered into robust multivariable linear regression models for analysis. Analyses for three and twelve-month outcomes were performed separately and all models were controlled for preoperative SF-12, EQ-5D, or Oswestry Disability Index and Neck Disability Index scores, depending on outcome of interest. A priori variables included age, sex, history of diabetes mellitus, tobacco smoking status, surgery invasiveness, revision surgery status, and preoperative Modified Somatic Perception Questionnaire and Zung Depression Scale scores. Multicollinearity was explored post-regression with the variance inflation factor. A random effect for clustering of patients by surgeon was examined, but was removed from final analyses on the basis of limited contribution to the variance of the models. The level of significance was set at p < 0.05. The number of study participants for this study was based on a sample 32,33 size calculation for multiple linear regression . The estimate was based on
the multiple correlation coefficients that are obtained when the controlled a priori independent variables are included in the regression model (R2, C) and only the independent variable of interest is included in the regression model (R2, TjC). Using a conservative R2(C) of 0.05 and an (R2, TjC) of 0.05, an a level of 0.05, and a power of 0.90 and controlling for nine independent variables, a sample size of at least 192 was needed to detect an association between the preoperative daily morphine equivalent amount and patient-reported postoperative outcomes using multivariable linear regression analyses.
Source of Funding There was no external source of funding.
Results Cohort Characteristics f the 583 patients who underwent elective surgery to treat a structural lesion and were included in the final analysis, 350 (60%) underwent lumbar surgery, sixty-four (11%) underwent thoracolumbar surgery, and 169 (29%) underwent cervical spine surgery. The median preoperative daily morphine equivalent amount for the cohort was 8.75 mg (interquartile range, 0 to 37.5 mg), with 56% (326 patients) reporting some degree of preoperative opioid use. The twenty-four-hour (daily) distribution of the preoperative morphine equivalent amount for the cohort is presented in a histogram form in Figure 1.
O
Patient-Reported Outcomes With Mann-Whitney U tests, the SF-12 PCS and MCS scores were significantly improved (p < 0.001) at both the three and twelve-month follow-ups, as were the Oswestry Disability Index and Neck Disability Index scores and the EQ-5D scores (Table II). Significant differences between three and twelve months of followup were noted for the SF-12 MCS (p = 0.001) and EQ-5D (p = 0.03) scores.
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TABLE IV Multivariable Linear Regression Models of Oswestry Disability Index and Neck Disability Index Scores and EQ-5D Scores at Three and Twelve Months Postoperatively Oswestry Disability Index and Neck Disability Index Scores* Variable
At Three Months
EQ-5D Scores*
At Twelve Months
At Three Months 0.07 (20.03 to 0.18)
At Twelve Months
Preoperative outcome score
0.25 (0.16 to 0.34)†
0.19 (0.09 to 0.29)†
Preoperative opioid use
0.06 (0.03 to 0.10)†
0.05 (0.02 to 0.09)†
Revision surgery
0.45 (22.57 to 3.46)
20.48 (23.55 to 2.59)
Level 1 versus level 0 (reference)
0.43 (24.34 to 5.19)
3.47 (21.18 to 8.12)
Level 2 versus level 0 (reference) Level 3 versus level 0 (reference)
0.77 (23.85 to 5.40)
3.07 (21.51 to 7.65)
20.02 (20.08 to 0.04)
20.04 (20.08 to 0.01)
20.41 (26.27 to 5.46)
0.90 (24.57 to 6.38)
20.01 (20.08 to 0.07)
20.02 (20.08 to 0.04)
0.28 (0.18 to 0.39)
0.23 (0.13 to 0.33)
20.001 (20.002 to 0.000)
20.001 (20.002 to 0.000)
21.42 (24.22 to 1.39)
20.47 (23.30 to 2.35)
20.01 (20.05 to 0.02)
20.02 (20.05 to 0.01)
20.001 (20.001 to 20.000)‡ 0.01 (20.03 to 0.05)
0.08 (20.01 to 0.17) 20.001 (20.001 to 20.000)‡ 0.02 (20.01 to 0.06)
Surgery invasiveness
Age in years Male versus female (reference)
0.001 (20.059 to 0.060)
20.02 (20.07 to 0.03)
Diabetes
2.82 (20.47 to 6.10)
4.63 (1.20 to 8.06)†
0.02 (20.02 to 0.05)
20.03 (20.07 to 0.01)
Current smoker
4.03 (0.84 to 7.22)†
3.24 (20.15 to 6.62)
20.03 (20.07 to 0.01)
20.03 (20.07 to 0.01)
Preoperative Modified Somatic Perception Questionnaire score
0.77 (0.42 to 1.13)†
1.21 (0.80 to 1.62)†
20.01 (20.01 to 0.00)‡
20.02 (20.2 to 20.01)‡
Preoperative Zung Depression Scale score
0.17 (20.30 to 0.37)
0.28 (0.08 to 0.49)†
20.004 (20.007 to 20.001)‡
20.004 (20.007 to 20.002)‡
0.17
0.29
Coefficient of determination
0.30
0.33
*The values are given as the beta, with the 95% confidence interval in parentheses. †These values were significant at p < 0.001. ‡These values were significant at p < 0.05.
Multivariable Models of SF-12 PCS and MCS Scores, Combined Oswestry Disability Index and Neck Disability Index Score, and EQ-5D Score Separate robust multivariable analyses demonstrated that increased preoperative opioid use was a significant predictor (p < 0.05) of decreased SF-12 PCS and MCS scores at three and twelve months postoperatively (Table III). Every 10-mg increase in the morphine equivalent amount taken preoperatively in a twentyfour-hour period predicted a 0.3 decrease in SF-12 PCS and MCS scores at three and twelve months postoperatively. Other significant predictors (p < 0.05) of decreased SF-12 PCS scores at three and twelve months postoperatively included preoperative SF-12 PCS score, age, and preoperative Modified Somatic Perception Questionnaire score. Preoperative SF-12 MCS and Modified Somatic Perception Questionnaire scores were also significant predictors (p < 0.05) of decreased SF-12 MCS scores at three and twelve months. The preoperative Zung Depression Scale score was only a significant predictor (p < 0.05) at twelve months postoperatively. Preoperative opioid use was also found to be a significant predictor (p < 0.001) of increased postoperative Oswestry Disability Index and Neck Disability Index scores at three and twelve months postoperatively (Table IV). Specifically, in the Oswestry Disability Index and Neck Disability Index score, every 10-mg increase in the morphine equivalent amount taken preoperatively
in a twenty-four-hour period predicted a 0.6 increase at three months and a 0.5 increase at twelve months. The preoperative Oswestry Disability Index and Neck Disability Index and the Modified Somatic Perception Questionnaire scores were also significant predictors (p < 0.001) of increased Oswestry Disability Index and Neck Disability Index scores at three and twelve months postoperatively. Smoking was a significant predictor (p < 0.001) at three months postoperatively only, while diabetes and preoperative Zung Depression Scale score were significant predictors (p < 0.001) at twelve months postoperatively only. Preoperative opioid use was a significant predictor (p < 0.05) of decreased EQ-5D scores at three and twelve months postoperatively (Table IV). Specifically, every 10-mg increase in morphine equivalent amount taken preoperatively in a twenty-four-hour period predicted a 0.01 decrease in the EQ-5D score at three and twelve months postoperatively. Other significant predictors (p < 0.05) of decreased EQ-5D scores at three and twelve months postoperatively included preoperative Modified Somatic Perception Questionnaire and Zung Depression Scale scores. Discussion ithin the context of growing national concern over the deleterious effects of physician-prescribed opioids, we examined whether increased opioid use in the preoperative period
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predicted worse patient-reported outcomes following elective spine surgery. The 56% prevalence of preoperative opioid use in our cohort is similar to that shown in other studies14-18. We demonstrated that after controlling for multiple demographic and clinical variables, increased preoperative opioid use was a significant predictor of adverse patient-reported outcomes. Previous work has examined preoperative opioid use as a predictor of clinical outcome after spine surgery. J¨onsson found that regular consumption of analgesics preoperatively was associated with increased postoperative pain in patients with central lumbar spinal stenosis17. However, no details were provided as to the type of analgesics used preoperatively. A recent reanalysis of the Spine Patient Outcomes Research Trial (SPORT) cohort aimed at identifying treatment effect predictors found that preoperative opioid use did have a significant treatment effect after minimally adjusted analyses, but significance did not carry over into subsequent multivariable analysis18. Studies that have further examined preoperative opioid use as a potential predictor of outcome are limited by their treatment of opioid use as a categorical (as opposed to a continuous) variable. In a retrospective cohort study of 488 patients undergoing anterior cervical discectomy and fusion, Anderson et al. identified weak opioid use as a potential negative predictor for clinical success from a multivariable model of several prognostic factors, but subsequent stepwise regression analysis did not demonstrate significance16. Their cohort reported a 70% prevalence of preoperative opioid use, which was subsequently dichotomized into weak and strong use. Clinical success was defined as a Neck Disability Index improvement of >15 points, maintained or improved neurologic examination, no adverse events, and no revision surgery. No definition on the weak or strong designation of opioids was provided. Lawrence et al.14 examined ninety-one patients undergoing anterior cervical discectomy and fusion and separated them into two groups based on whether they required daily opioids for at least six months preoperatively or not. That single-surgeon cohort demonstrated a 52% prevalence of opioid use. There was also a significantly lower incidence of good or excellent results following surgery for those requiring opioids (51%) compared with those not requiring opioids (86%). There was a significantly higher incidence of poor results in the opioid group (32%) compared with the non-opioid group (0%)14. Clinical outcome was based on pain assessment, medication use, activity level, and work status. Analysis in that study did not control for other possible significant variables. Currently, to our knowledge, no validated stratification system of preoperative opioid use in the population undergoing elective spine surgery exists. Subgroups have been proposed on the basis of expert opinion, as by the Productive Rehabilitation Institute of Dallas for Ergonomics (PRIDE) Research Foundation for patients with chronic spinal disorders. On the basis of the daily morphine equivalent amount, patients who reported opioid use were divided into subgroups of low (£30 mg), medium (31 to 60 mg), high (61 to 120 mg), and very high (>120 mg)34. Knowledge that increased preoperative opioid use negatively predicts outcome may provide motivation to both patient
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and surgeon to decrease or to eliminate opioid use prior to surgery. The amount of opioid consumption that actually leads to a clinically relevant difference in these outcomes remains unknown. The minimal clinically important difference of patientreported outcomes in various populations undergoing spine surgery has been proposed by other investigators35-41. These values stem from populations undergoing specific spine surgery and are not globally applicable to our cohort, which is inclusive of all elective spine cases. For example, the range of the minimal clinically important difference for the SF-12 PCS score is 7.0 to 12.239 in patients undergoing primary anterior cervical discectomy and fusion, compared with 3.2 to 6.1 for patients undergoing revision surgery for symptomatic lumbar pseudarthrosis38. Increased preoperative Modified Somatic Perception Questionnaire score was a significant predictor (p < 0.05) for worse patient-reported outcomes. Early work has already linked somatization and other psychological factors with poorer outcomes in various surgical spine cohorts42-45. Main et al. proposed the Distress and Risk Assessment Method (DRAM) as a tool to predict outcome in patients with low back pain46. This method incorporates the Zung Depression Scale and Modified Somatic Perception Questionnaire scores to stratify patients as normal, at risk, or distressed. However, follow-up studies demonstrated that the DRAM did not predict disability outcome in patients undergoing lumbar surgery47,48. More recently, Chaichana et al. demonstrated that an increased Modified Somatic Perception Questionnaire score was associated with a decreased likelihood of achieving a minimal clinically important difference in the SF-36 and Oswestry Disability Index scores following lumbar discectomy49. Although the benefit of screening tools such as the DRAM remains to be validated, our results support the consideration of somatization or anxiety in the preoperative period. The strengths of our study included a large sample size, prospective design, inclusiveness of all elective spine cases, use of multivariable analyses, and treatment of preoperative opioid use as a continuous variable. Although larger than previous studies, our single-center study still describes a relatively small sample size. The inclusion of all types of elective spine surgical procedures may be a confounding variable. We attempted to account for this with the introduction of a categorical covariate that groups procedures of like invasiveness. Groupings were formed on the basis of the experience of the senior author (C.D.) and have not been validated. Our analyses also did not account for duration of preoperative opioid use. Use of state registries that track opioid prescriptions filled for a patient may provide a more accurate reflection of opioid use. Importantly, we also did not track continued opioid use at the three and twelve-month postoperative visits, and this represents a flaw in our study design. It is possible that opioid use in the postoperative period may have an impact on patient-reported outcomes to a greater degree than preoperative opioid use. The fact that our subsequent models did not include postoperative opioid use as a covariate was a limitation to our study. Despite these limitations, our work represents a timely investigation into whether preoperative opioid use has a negative
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impact on spine surgery outcomes. Additional prospective data comparing the outcomes of patients who successfully decrease their opioid intake prior to surgery, and those who do not, would provide more definitive evidence on the impact of preoperative opioid use on patient-reported outcomes. Subsequent work should also assess the impact of additional interventions, such as psychiatric screening, counseling, and therapy in the preoperative period, as well as close opioid monitoring postoperatively. n
David Shau, BS Harrison Kay, BS Chi Zhang, BA Clinton Devin, MD Department of Orthopaedics & Rehabilitation, Vanderbilt University Medical Center, 1215 21st Avenue South, Medical Center East, South Tower, Suite 4200, Nashville, TN 37232. E-mail address for D. Lee: [email protected]. E-mail address for C. Devin: [email protected]
Dennis Lee, MD Sheyan Armaghani, MD Kristin R. Archer, PhD, DPT Jesse Bible, MD
Matthew J. McGirt, MD Carolina Neurosurgery & Spine Associates, 225 Baldwin Avenue, Charlotte, NC 28204
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