Article
Evaluation of Readmission Rates for Carotid Endarterectomy Versus Carotid Artery Stenting in the US Medicare Population
Vascular and Endovascular Surgery 2014, Vol. 48(3) 217-223 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1538574413518120 ves.sagepub.com
Edgar Luis Galin˜anes, MD1, Viktor Y. Dombroviskiy, MD, MPH, PhD2, Colleen S. Hupp, DO1, Robin L. Kruse, PhD3, and Todd R. Vogel, MD, MPH1
Abstract Objective: We evaluated rates and identified predictors of readmission in the Medicare population after carotid endarterectomy (CEA) compared to carotid artery stenting (CAS). Methods: MedPAR data (2005-2009) were used to select patients who underwent CEA or CAS (utilizing International Classification of Diseases, Ninth Revision, Clinical Modification codes). Readmission was evaluated using chi-square and multivariable logistic regression. Results: A total of 235 247 carotid interventions were performed (211 118 CEA and 24 129 CAS). Readmission rates (%) for patients undergoing CEA and CAS, respectively, were 8.84 and 11.11 (30 days; P < .0001); 13.31 and 17.98 (60 days; P < .0001); and 16.86 and 22.68 (90 days; P < .0001). Patients aged >80 (odds ratio [OR] ¼ 1.25; 95% confidence interval [CI] ¼ 1.20-1.30) and patients with renal failure (OR ¼ 1.6 95%; CI ¼ 1.56-1.73), congestive heart failure (OR ¼ 1.6; 95%CI ¼ 1.57-1.73), diabetes (OR ¼ 1.4; 95% CI 1.27-1.52), and CAS (OR ¼ 1.2; 95%CI ¼ 1.15-1.25) were more likely to be readmitted. Conclusions: Interventions for carotid artery disease had high overall readmission rates. After adjustment for comorbidities, utilization of less invasive techniques (CAS) did not result in lower readmission rates. Further evaluation is needed to determine strategies to reduce hospital readmission rates after carotid interventions. Keywords carotid, endarterectomy, stenting
Introduction An estimated one-quarter of Medicare patients undergoing a vascular surgery have a hospital readmission within 30 days of their initial procedure.1 Billions of health care dollars are spent annually on hospital readmissions alone (Medicare Payment Advisory Commission). As part of the Patient Protection & Affordable Care Act, the Center for Medicare and Medicaid Services (CMS) has been prompted to minimize Medicaid and Medicare reimbursement costs to hospitals with excess readmission rates that are viewed as unnecessary burden on the US health care system. Carotid endarterectomies (CEAs) are one of the most common vascular surgery procedures performed in the United States.2 Many studies have established noninferiority of carotid artery stenting (CAS) as it relates to feasibility, effectiveness, and complications.3,4 However, with the increase in utilization of this minimally invasive procedure, we felt it was prudent to determine readmission rates and identify predictors of readmission between both procedures in an attempt to establish best practice and costeffectiveness.
Methods Data Sources Data for analysis were extracted from the CMS MedPAR (Medicare Provider Analysis and Review) file for the years 2005 to 2009. This file encloses the discharge abstracts for hospitalized Medicare beneficiaries that provide information regarding their demographic characteristics, date and type of hospital admission, the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)
1 Division of Vascular Surgery, University of Missouri, School of Medicine, Columbia, MO, USA 2 Department of Surgery, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, New Jersey, MO, USA 3 Department of Family and Community Medicine, University of Missouri, School of Medicine, Columbia, MO, USA
Corresponding Author: Todd R. Vogel, Department of Surgery, Division of Vascular Surgery, University of Missouri Hospital & Clinics, One Hospital Drive, Columbia, MO 65212, USA. Email: [email protected]
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
218
Vascular and Endovascular Surgery 48(3)
codes for diagnoses, and procedures during the hospital stay with the date when each procedure was performed, date and destination at discharge, date of death, and so on. The unique personal identifier for each Medicare beneficiary allows tracking of hospitalizations over time.
Study Population At first, we selected all Medicare beneficiaries aged 65 years and older, who were electively hospitalized and underwent carotid artery stenting (CAS; ICD-9-CM procedure code 00.63) or carotid endarterectomy (CEA; ICD-9-CM procedure code 38.12). Among them, we included in the study cohort only those who underwent procedure for the first time, and all observations with subsequent carotid interventions were excluded from the analysis. Symptomatic patients were identified with the ICD-9-CM diagnosis codes 362.34, 435.x, and 781.4 in any diagnosis position. To identify various postoperative complications, we used the following ICD-9-CM diagnosis codes in any of the 9 secondary diagnoses positions: 997.00, 997.01, 997.02, 997.09, 433.11, 434.01, 434.11, and 434.91—for stroke; 997.1, 410.00-410.02, 410.10-410.12, 410.20-410.22, 410.30-410.32, 410.40-410.42, 410.50-410.52, 410.60-410.62, 410.70-410.72, 410.80-410.82, 410.90-410.92, and 427.5—for cardiac complications including myocardial infarction (MI); 997.3x, 480.x, 481, 482.0-482.2, 482.3x, 482.4x, 482.8x, 482.9, 483.x, 484.x, 485, 486, 507.0, 512.1, 518.4, 518.5, 518.81, 518.82— for respiratory complications and pneumonia; 997.5, 584.x, and 593.81—for renal complications including acute renal failure; 038.0, 038.1x, 038.2, 038.3, 038.4x, 038.8, 038.9, 995.91, 995.92, 998.0, 785.52, 996.61, 996.62, 998.59, 999.3x—for sepsis and bloodstream infection; 599.0 and 996.64—for urinary tract infection (UTI); and 998.30-998.32, 998.51, 998.6, and 998.83—for surgical site infection (SSI). Comorbidities in the study population were evaluated with the (Agency for Healthcare Research and Quality (AHRQ)’s Healthcare Cost and Utilization Project (HCUP) comorbidity software, version 3.5 (available at http://www.hcup-us.ahrq.gov/toolssoftware/ comorbidity/comorbidity.jsp#download).
Statistical Analysis All statistical analyses were performed with the SAS software, version 9.2 (SAS Institute, Cary, North Carolina) and a value P < .05 was considered statistically significant. The 30-day, 60-day, and 90-day readmission rates were calculated by dividing the number of patients who were readmitted to the hospital during these time periods after initial discharge by the number of patients who were discharged alive after initial hospitalization and were expressed as a percentage. To evaluate the difference between the 2 groups, we used the chi-square analysis with computing odds ratios (ORs) and 95% confidence intervals (95% CIs). Significant results in bivariate analysis were tested by multivariable logistic regression analysis with adjustment by age, gender, race, type of surgical procedure, postoperative complications, and comorbidities. We also assessed
the difference in the 90-day, readmission-free survival between patients who underwent CAS or CEA with adjusted Cox proportional hazards modeling and Kaplan-Meier survival curves.
Results A total of 235 247 patients with carotid interventions that met inclusive criteria were selected. Among them, the majority (211 118) of patients underwent CEA and only one-tenth (24 129) underwent CAS. Characteristics of the study population are displayed in Table 1. As shown in Table 1, there was no difference in mean age between patients in both the surgical groups. However, age distribution among patients with CAS differed from those with CEA. Proportions of youngest (65-69 years) and oldest (80 years and older) patients undergoing CAS were significantly greater than among patients undergoing CEA (P < .0002), whereas the fraction of patients at age 70 to 79 years was significantly smaller (P < .0002). In both the surgical groups, males predominated over females (P < .0002). We also found racial disparities in utilization of both surgical procedures. Among patients who underwent CAS, the proportion of whites was smaller (P < .0002) and proportions of blacks and Hispanics were greater (P < .0002) than among patients who underwent CEA. There were differences in the rates of some comorbidity diseases between the 2 surgical groups. Patients who underwent CAS were more likely to have diabetes with chronic complications (P ¼ .012), congestive heart failure, peripheral vascular disease, pulmonary circulation disease, and renal failure (P < .0002 for all) and less likely to have chronic pulmonary disease (P ¼ .001), diabetes without chronic complications (P ¼ .025), hypertension, and obesity (P < .0002 for all) than patients with CEA. Symptomatic patients accounted for 2.7% of all study population. A higher rate of symptomatic patients was found among those undergoing CAS than those undergoing CEA (P < .0002). Overall, the hospital readmission rates after CAS were significantly greater than after CEA. We found this within various time intervals after the index discharge. In the bivariate chisquare analysis, the rates of readmissions after CAS and CEA were, respectively, 11.1% and 8.8% during 30 days after discharge, 18.0% and 13.3% during 60 days, and 22.7% and 16.9% during 90 days after the index discharge; P < .0001 for all comparisons. There was no difference in the readmission rates during 30 days after discharge between symptomatic and asymptomatic patients. However, within 60 and 90 days after discharge, asymptomatic patients were more likely to be readmitted to the hospital than symptomatic patients (OR ¼ 1.10; 95% CI 1.02-1.19; P ¼ .008; and OR ¼ 1.10; 95% CI 1.031.17; P ¼ .006, respectively). Because of some variations in patients’ characteristics between the 2 surgical groups, we performed multivariable logistic regression analysis with readmission as an outcome variable of the model and age, gender, race, symptomatic/ asymptomatic status, postoperative complications and comorbidities as predictors of this outcome. The results of this
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
Galin˜anes et al
219
Table 1. Characteristics of the Study Population. Procedures Characteristics Age, years (mean + SD) Age groupsa 65-69 70-74 75-79 80þ Gendera Male Female Racea White Black Hispanic Other Missing Comorbiditiesa Congestive heart failure Coagulopathy Diabetes without chronic complications Diabetes with chronic complications Hypertension Obesity Peripheral vascular disease Pulmonary circulation disease Renal failure Symptomatic patientsa
CAS (N ¼ 24 129)
CEA (N ¼ 211 118)
P Value
75.59 + 7.24
75.58 + 6.73
.0002
43 51 54 61
(20.4) (24.4) (25.8) (29.4)
.0367 .0377 .0393 .0392
14 510 (60.1) 9619 (39.9)
119,627 (56.7) 91 491 (43.3)
.0690 .0690
22 384 (93.08) 932 (3.88) 254 (1.06) 479 (1.98) 80
198 536 (94.35) 6556 (3.12) 1715 (0.82) 3615 (1.71) 696
.0523 .0414 .0249 .0201
2641 (10.95) 210 (0.87) 6288 (26.06) 519 (2.15) 17 440 (72.28) 768 (3.18) 6050 (25.07) 269 (1.11) 2122 (8.79) 826 (3.42)
13 403 1759 56 438 4045 164 606 8586 40 074 1627 12 033 5597
.1642 .0044 .0152 .0163 .0166 .0476 .1474 .0352 .1194 .0449
5284 (21.9) 5498 (22.8) 5813 (24.1) 7534 (31.2)
133 543 489 953
(6.35) (0.83) (26.73) (1.92) (77.97) (4.07) (18.98) (0.77) (5.70) (2.65)
Abbreviations: CAS, and carotid artery stenting; CEA, carotid endarterectomy; SD, standard deviation. a Variables are reported as number of patients (%).
analysis confirmed our previous findings. After risk adjustment, patients who underwent CAS were still more likely to be readmitted to the hospital when compared to their counterparts with CEA within 30 days (OR ¼ 1.21; 95% CI 1.15-1.26; P < .0001), 60 days (OR ¼ 1.34; 95% CI 1.29-1.39; P < .0001) and 90 days after discharge (OR ¼ 1.36; 95% CI 1.31-1.40). In the multivariable analysis, asymptomatic patients compared to symptomatic ones were still more likely to be readmitted within 60 days (OR ¼ 1.12; 95% CI 1.03-1.20; P ¼ .005) and 90 days after discharge (OR ¼ 1.11; 95% CI 1.03-1.18; P ¼ .004). The other predictors of the hospital readmission within studied time intervals were advanced age, female gender, black race and Hispanic ethnicity, the majority of studied comorbid diseases (congestive heart failure, chronic pulmonary disease, coagulopathy, diabetes, peripheral vascular disease, pulmonary circulation disease, renal failure), and various postoperative complications: cardiac, respiratory, and renal complications; sepsis, SSI, and UTI; postoperative stroke. Risk factors for readmission during 90 days after index discharge are presented in Figure 1. Figure 2 presents Kaplan-Meier curves for readmission-free survival of patients during 90 days after discharge from the hospital where CAS or CEA were performed. To perform readmission-free survival analysis with risk adjustment, we
used Cox proportional hazards regression modeling with adjustment by patient’s age, gender, race, comorbidities, symptomatic/asymptomatic status, and postoperative complications and calculated hazard ratios (HR) with 95% CI to examine a cumulative effect of these risk factors on readmission during 90 days after discharge. This analysis also demonstrated a higher readmission frequency after CAS than after CEA (HR ¼ 1.29; 95% CI 1.26-1.32; P < .0001) and among asymptomatic patients versus symptomatic ones (HR ¼ 1.07; 95% CI 1.02-1.12; P ¼ .005). All risk factors for readmission, which were discovered by multivariable logistic regression analysis remained associated with readmission in Cox proportional hazards regression modeling. We evaluated the most frequent principal diagnosis at hospital readmission. Coronary atherosclerosis of native coronary artery was the most frequent cause of readmission after both CAS and CEA, with greater frequency after CAS (P < .0002). The ranks of the other principal diagnoses in the 2 groups slightly varied. Frequencies of congestive heart failure and atherosclerosis of extremities as causes for readmission after CAS were greater than after CEA (P < .0002 and P ¼ .0003, respectively), whereas occlusion and stenosis of carotid artery without cerebral infarction were more frequent reasons for readmission after CEA than after CAS (P < .0002).
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
220
Vascular and Endovascular Surgery 48(3)
Figure 1. Risk factors for readmission during 90 days after index discharge.
Figure 2. Readmission-free survival after carotid endarterectomy (CEA) and carotid artery stenting (CAS).
Discussion Our analysis found an unexpectedly high readmission rates associated with carotid interventions among the Medicare population. Readmission rates (%) for patients undergoing CEA
and CAS, respectively, were 8.84 and 11.11 at 30 days (P < .0001), 13.31 and 17.98 at 60 days (P < .0001), and 16.86 and 22.68 at 90 days (P < .0001). Recently, using the ACS National Surgical Quality Improvement Program (ACS-NSQIP) database, Curran et al identified a 7.5% rate of 30-day readmission
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
Galin˜anes et al
221
among patients undergoing CEA.25 Jackson et al reported a lower 30-day readmission rate of 4.2% for patients undergoing CEA at a single university hospital institution.5 The low readmission rate reported by Jackson et al most likely represents single-institutional bias, as our rates are similar to other large population database analyses. When using large population data sets, readmission for carotid interventions appears to be greater than expected. Using ICD9-CM codes, Kennedy et al was able to identify outcomes of CEAs performed in the State of California and reported a 30day readmission rate of 7% for CEA.6 Stuart et al analyzed surgical databases and observed an 8% rate of readmission after CEA in the United Kingdom.7 Although greater than expected, our analysis of the Medicare & Medicaid data sets demonstrated a 30-day hospital readmission rate of 11% and 8.8% for CAS and CEA, respectively, which appears to be consistent with the current published literature using large population databases. Our results demonstrate a greater likelihood for hospital readmission associated with CAS compared to CEA. After adjusting for confounding factors, patients undergoing CAS were almost at 1.5 times greater risk of readmission than patients undergoing CEA. This risk continued to increase at 60 and 90 days after procedure. Patients who underwent carotid stenting were 1.29 times as likely to be readmitted (P < .0001) compared to those undergoing endarterectomy. Ultimately, our data demonstrate no benefit of an endovascular approach with respect to readmission rates associated with carotid artery interventions. Higher readmission rates among patients undergoing endovascular procedures than open operation have been reported in the literature. Vogel et al reported a 30-day readmission rate of 15.3% in patients undergoing endovascular lower extremity revascularization compared to a rate of 13.9% associated with open procedures.8 In addition, Casey et al demonstrated higher rates of hospital readmission in patients undergoing endovascular abdominal aortic aneurysm repair those going for open repair.9 Our data coincide with the trend of greater readmission rates associated endovascular approaches compared to open surgery. We found the diagnosis of coronary artery disease to be the most common reason for readmission in both the groups. This is consistent with Jencks et al who found cardiac complications to be the most common reason for readmission following surgery and the third most common reason for readmission in patients undergoing vascular surgery following further surgical interventions and amputations.1 This was further suggested by Kind et al who found congestive heart failure to be the most common reason for admission among Medicare beneficiaries between the years 2005 and 2006.10 Using the Society for Vascular Surgery Vascular Registry (SVS-VR), Sidawy et al demonstrated that symptomatic and asymptomatic patients undergoing CAS had significantly higher 30-day postprocedure incidence of death/stroke/MI when than patients undergoing CEA (6.42% vs 2.62%, P < .0001).11 Our results are consistent with those found in the SVS-VR, indicating that in readmission among patients undergoing CAS, medical reasons are more commonly
cited. In comparison, patients undergoing CEA had great rates of readmission attributed to restenosis and occlusion. In the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) trial, repeat revascularization was 4.2% to 5.8% greater in the CEA group but was found to be nonsignificant.4 The largest cohorts of patients being treated in each group were octogenarians comprising approximately 30%. It was also found that these patients had a higher likelihood of being readmitted at all time periods. Kind et al demonstrated a trend toward greater 30-day readmission rates among Medicare beneficiaries with advancing age.10 Patients aged 85 or older had 30-day readmission rate of 25.1% compared to those aged 65 to 69 who had 8% of readmission rate at 30 days. Additionally, it was noted that there was increase in utilization of stents in this group as well. Data from the CREST trial showed that these patients also have a higher stroke rate (almost 12%) with use of CAS.12 These data suggest that octogenarians are a highrisk group of patients and may need more intense pre- and postoperative follow-up. Postoperative complications were found to be significant predictors for readmission. Patients who had a postoperative stroke were 2.8 times as likely to be readmitted (P < .0001), patients who had surgical site infections were 2.4 times as likely to be readmitted (P < .0001), followed by sepsis and UTIs. Kassin et al evaluated 30-day postoperative readmission rates for general surgery patients and found that postoperative complications appear to drive readmissions in surgical patients.13 Our data and findings also support the finding that hospital complications after CEA and CAS are strong predictors of readmission. Finding ways to minimize these complications may significantly improve the readmission rate in our study population. As well, because the rates of stroke after CAS are known to be higher, and stroke was the strongest predictor of readmission, this may account for higher readmission rate after CAS. Comorbidities were also significant predictors of readmission. We have demonstrated that patients with congestive heart failure were 1.6 times as likely to be readmitted, patients with renal failure were 1.6 times as likely to be readmitted, and diabetics were 1.4 times more likely to be readmitted. Previous studies following other vascular-related surgeries and procedures have identified these as risk factors for readmission.14,15 Identifying these patients who are at high risk may allow for better postoperative planning to help prevent readmission. It may be that at the time of discharge those with known risk factors not only follow-up with vascular surgeon and that a structure is in place to follow up with practitioners managing their comorbidities. Accounting for confounders, we were able to identify advanced age (>80), female gender, black and Hispanic ethnicity, and the presence of comorbidities as predictors of readmission. Hannan et al identified similar variables (advanced age, female gender, and black race) as predictors of 30-day readmission after coronary bypass surgery.16 Moreover, in a single-institutional, retrospective study, Jackson et al identified advanced age and diabetes as a predictors of readmission, specifically for vascular procedures (P ¼ .39).5
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
222
Vascular and Endovascular Surgery 48(3)
Strategies need to be implemented for reduction in health care costs in the future, with the current focus of CMS on readmission rates. This can prove to be difficult as the definition of readmission depends on certain circumstances. Vascular surgery is a dynamic field where many procedures can be performed in a ambulatory setting that may require multiple visits in a short period, which collectively aid in the ultimate care of the patient. Jackson et al identified a 3% planned readmission rate accounting for preoperative workups, contralateral lower extremity endovascular revascularization following prior unilateral procedure, or diagnostic angiogram following revascularization.5 Unplanned readmission rates were approximately 8.9%, with surgical causes of readmission (wound infection, hematoma, or revascularization) accounting for two-thirds of those admissions.5 Cardiac and infectious causes accounted for only a third of hospital readmission rates that were unplanned.5 Brooke et al suggested a 4-phase model consisting of patient demographics and procedures, postoperative hospital course, the discharge, and readmission in analyzing readmissions rates, and attempting to identify areas of intervention.17 Many articles, including ours, have identified predictors of readmission targeting the first phase; however, few successful strategies exist to minimize radmission. Wennberg et al have suggested postdischarge telephone calls, while Hernandez et al suggested early clinical follow-up to be successful in decreasing readmission rates.18,19 Despite the implementation of various strategies all along Brookes’ 4-phase model, a retrospective meta-analysis of the available literature suggested that no single intervention implemented alone was regularly associated with reduced risk of 30-day rehospitalization.20 In analysis of the ACS-NSQUIP database, Lawson et al identified postoperative complications as the single most predictive factor in surgical readmissions and an area with most potential for impact.21 This analysis supports these findings with stroke, surgical site infection, respiratory, and cardiac complications, all associated with readmission. With the ubiquitous Patient Protection & Affordable Care Act and its impending financial penalties on readmission rates, it seems evident based on the readmission rates that CEA is superior to CAS on a cost–benefit prospective. Using a hypothetical cohort model and Medicare costs, Young et al found a 59% probability that CEA would become the procedure of choice based on lifetime expenditure.22 The CEA was associated with a lifetime cost of US$35 200 compared to US$52 900 for CAS. Kilaru et al concluded similar results suggesting that in order for CAS to be fiscally comparable, the mortality and major stroke rates of CAS must be at least equivalent to if not less than those of CEA.23 This analysis has several limitations. Ideally, a doubleblinded randomized control study would be the preferred methodology to assess cause and relationship; however, our retrospective analysis can provide insight and direction for further investigations. Furthermore, our study is limited by data acquisition relying on administrative codes. The Medicare data are an administrative database and clinical information may be limited by the ICD-9-CM and CPT codes with
respect to definition of indications and coding that could vary between institutions and coders. In addition, certain complications may not be captured in administrative data sets. Refined clinical data are not possible from administrative data; however, this study describes rates of procedures and readmission on thousands of Medicare patients. Another limitation is that confounding by indication may occur, as the study is not randomized. Indications for treatment may be biased in relation to future health outcomes. Sicker patients may have been preferentially treated with less invasive procedures skewing results. Goodney et al, using the MEDPAR database for 1994 to 1999, found a 30-day hospital readmission rates for high-risk patients undergoing CEA to be 11% comparable to our 11% readmission rates for CAS.24 In our analysis, patients undergoing CAS had greater number of comorbidities and perhaps were more representative of the patient population analyzed by Goodney et al previously when CAS was not routinely performed. These results also suggest that hospital readmission rates are more attributed to patient population and less a factor of surgical approach. Nonetheless, after risk adjustment, patients who underwent CAS were still more likely to be readmitted to the hospital when compared to their counterparts with CEA within 30 days, 60 days, and 90 days after discharge. In conclusion, our data demonstrate a high readmission rate for patients undergoing carotid intervention. It may be that while as surgeons we perceive these cases as minimally invasive and some of the lower risk surgery performed, these patients’ comorbidities may not be as well optimized as possible pre- and postoperatively, contributing to the high readmission rate. Identifying predictors of readmission is essential to help improve outcomes. By understanding the risk factors that predispose readmission, these patients can be targeted for better postoperative care. In addition, postoperative complications continue to drive readmissions in surgical patients, and continued efforts to minimize these complications must still be a goal. In addition, patients who undergo CAS must be chosen carefully, as a less invasive procedure does not always mean lower complications as seen by their higher readmission rate. Further evaluation is warranted into hospital readmission after carotid intervention to help further ascertain ways to decrease the readmission rate. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
References 1. Jencks SF, Williams MV, Coleman EA. Rehospitalizations among patients in the Medicare fee-for-service program. N Engl J Med. 2009;360(14):1418-1428. 2. Anderson PL, Gelijns A, Moskowitz A, et al. Understanding trends in inpatient surgical volume: vascular interventions, 1980-2000. J Vasc Surg. 2004;39(6):1200-1208.
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
Galin˜anes et al
223
3. Brott TG, Hobson RW 2nd, Howard G, et al. Stenting versus endarterectomy for treatment of carotid-artery stenosis. N Engl J Med. 2010;363(1):11-23. 4. Mantese VA, Timaran CH, Chiu D, Begg RJ, Brott TG. The carotid revascularization endarterectomy versus stenting trial (CREST): stenting versus carotid endarterectomy for carotid disease. Stroke. 2010;41(10 suppl):S31-S34. 5. Jackson BM, Nathan DP, Doctor L, Wang GJ, Woo EY, Fairman RM. Low rehospitalization rate for vascular surgery patients. J Vasc Surg. 2011;54(3):767-772. 6. Kennedy BS, Fortmann SP, Stafford RS. Elective and isolated carotid endarterectomy: health disparities in utilization and outcomes, but not readmission. J Natl Med Assoc. 2007;99(5):480-488. 7. Stuart WP, Hussey KK, Eifell RK, Drummond R, Ford I, Welch GH. Using centrally held data to validate carotid surgery outcome data. Stroke. 2013;44(6):1670-1675. 8. Vogel TR, Kruse RL. Risk factors for readmission after lower extremity procedures for peripheral artery disease. J Vasc Surg. 2013;58(1):90-97.e1-e4. 9. Casey K, Hernandez-Boussard T, Mell MW, Lee JT. Differences in readmissions after open repair versus endovascular aneurysm repair. J Vasc Surgery. 2013;57(1):89-95. 10. Kind AJ, Bartels C, Mell MW, Mullahy J, Smith M. For-profit hospital status and rehospitalizations at different hospitals: an analysis of Medicare data. Ann Intern Med. 2010;153(11):718-727. 11. Sidawy AN, Zwolak RM, White RA, Siami FS, Schermerhorn ML, Sicard GA. Risk-adjusted 30-day outcomes of carotid stenting and endarterectomy: results from the SVS Vascular Registry. J Vasc Surg. 2009;49(1):71-79. 12. Hobson RW 2nd, Howard VJ, Roubin GS, et al. Carotid artery stenting is associated with increased complications in octogenarians: 30-day stroke and death rates in the CREST lead-in phase. J Vasc Surg. 2004;40(6):1106-1111. 13. Kassin MT, Owen RM, Perez SD, et al. Risk factors for 30-day hospital readmission among general surgery patients. J Am Coll Surg. 2012;215(3):322-330. 14. Stewart RD, Campos CT, Jennings B, Lollis SS, Levitsky S, Lahey SJ. Predictors of 30-day hospital readmission after coronary artery bypass. Ann Thorac Surg. 2000;70(1):169-174.
15. Vogel TR, Dombrovskiy VY, Carson JL, Graham AM. Inhospital and 30-day outcomes after tibioperoneal interventions in the US Medicare population with critical limb ischemia. J Vasc Surg. 2011;54(1):109-115. 16. Hannan EL, Racz MJ, Walford G, et al. Predictors of readmission for complications of coronary artery bypass graft surgery. JAMA. 2003;290(6):773-780. 17. Brooke BS, De Martino RR, Girotti M, Dimick JB, Goodney PP. Developing strategies for predicting and preventing readmissions in vascular surgery. J Vasc Surg. 2012;56(2):556-562. 18. Wennberg DE, Marr A, Lang L, O’Malley S, Bennett G. A randomized trial of a telephone care-management strategy. N Engl J Med. 2010;363(13):1245-1255. 19. Hernandez AF, Greiner MA, Fonarow GC, et al. Relationship between early physician follow-up and 30-day readmission among Medicare beneficiaries hospitalized for heart failure. JAMA. 2010;303(17):1716-1722. 20. Hansen LO, Young RS, Hinami K, Leung A, Williams MV. Interventions to reduce 30-day rehospitalization: a systematic review. Ann Intern Med. 2011;155(8):520-528. 21. Lawson EH, Lee Hall B, Louie R, et al. Association between occurrence of a postoperative complication and readmission: implications for quality improvement and cost savings. Ann Surg. 2013;258(1):10-18. 22. Young KC, Holloway RG, Burgin WS, Benesch CG. A costeffectiveness analysis of carotid artery stenting compared with endarterectomy. J Stroke Cerebrovasc Dis. 2010;19(5): 404-409. 23. Kilaru S, Korn P, Kasirajan K, et al. Is carotid angioplasty and stenting more cost effective than carotid endarterectomy? J Vasc Surg. 2003;37(2):331-339. 24. Goodney PP, Stukel TA, Lucas FL, Finlayson EV, Birkmeyer JD. Hospital volume, length of stay, and readmission rates in high-risk surgery. Ann Surg. 2003;238(2):161-167. 25. Curran T, Lo RC, Fokkema M, Wyers M, Hamdan A, Chaikof E, Schermerhorn ML. Predictors of 30-Day Readmission and Post-Discharge Mortality Following Carotid Endarterectomy in the ACS-NSQIP. Journal of Vascular Surgery. 2013; 57(5):93S-94S.
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
Evaluation of Readmission Rates for Carotid Endarterectomy Versus Carotid Artery Stenting in the US Medicare Population
Vascular and Endovascular Surgery 2014, Vol. 48(3) 217-223 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1538574413518120 ves.sagepub.com
Edgar Luis Galin˜anes, MD1, Viktor Y. Dombroviskiy, MD, MPH, PhD2, Colleen S. Hupp, DO1, Robin L. Kruse, PhD3, and Todd R. Vogel, MD, MPH1
Abstract Objective: We evaluated rates and identified predictors of readmission in the Medicare population after carotid endarterectomy (CEA) compared to carotid artery stenting (CAS). Methods: MedPAR data (2005-2009) were used to select patients who underwent CEA or CAS (utilizing International Classification of Diseases, Ninth Revision, Clinical Modification codes). Readmission was evaluated using chi-square and multivariable logistic regression. Results: A total of 235 247 carotid interventions were performed (211 118 CEA and 24 129 CAS). Readmission rates (%) for patients undergoing CEA and CAS, respectively, were 8.84 and 11.11 (30 days; P < .0001); 13.31 and 17.98 (60 days; P < .0001); and 16.86 and 22.68 (90 days; P < .0001). Patients aged >80 (odds ratio [OR] ¼ 1.25; 95% confidence interval [CI] ¼ 1.20-1.30) and patients with renal failure (OR ¼ 1.6 95%; CI ¼ 1.56-1.73), congestive heart failure (OR ¼ 1.6; 95%CI ¼ 1.57-1.73), diabetes (OR ¼ 1.4; 95% CI 1.27-1.52), and CAS (OR ¼ 1.2; 95%CI ¼ 1.15-1.25) were more likely to be readmitted. Conclusions: Interventions for carotid artery disease had high overall readmission rates. After adjustment for comorbidities, utilization of less invasive techniques (CAS) did not result in lower readmission rates. Further evaluation is needed to determine strategies to reduce hospital readmission rates after carotid interventions. Keywords carotid, endarterectomy, stenting
Introduction An estimated one-quarter of Medicare patients undergoing a vascular surgery have a hospital readmission within 30 days of their initial procedure.1 Billions of health care dollars are spent annually on hospital readmissions alone (Medicare Payment Advisory Commission). As part of the Patient Protection & Affordable Care Act, the Center for Medicare and Medicaid Services (CMS) has been prompted to minimize Medicaid and Medicare reimbursement costs to hospitals with excess readmission rates that are viewed as unnecessary burden on the US health care system. Carotid endarterectomies (CEAs) are one of the most common vascular surgery procedures performed in the United States.2 Many studies have established noninferiority of carotid artery stenting (CAS) as it relates to feasibility, effectiveness, and complications.3,4 However, with the increase in utilization of this minimally invasive procedure, we felt it was prudent to determine readmission rates and identify predictors of readmission between both procedures in an attempt to establish best practice and costeffectiveness.
Methods Data Sources Data for analysis were extracted from the CMS MedPAR (Medicare Provider Analysis and Review) file for the years 2005 to 2009. This file encloses the discharge abstracts for hospitalized Medicare beneficiaries that provide information regarding their demographic characteristics, date and type of hospital admission, the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)
1 Division of Vascular Surgery, University of Missouri, School of Medicine, Columbia, MO, USA 2 Department of Surgery, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, New Jersey, MO, USA 3 Department of Family and Community Medicine, University of Missouri, School of Medicine, Columbia, MO, USA
Corresponding Author: Todd R. Vogel, Department of Surgery, Division of Vascular Surgery, University of Missouri Hospital & Clinics, One Hospital Drive, Columbia, MO 65212, USA. Email: [email protected]
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
218
Vascular and Endovascular Surgery 48(3)
codes for diagnoses, and procedures during the hospital stay with the date when each procedure was performed, date and destination at discharge, date of death, and so on. The unique personal identifier for each Medicare beneficiary allows tracking of hospitalizations over time.
Study Population At first, we selected all Medicare beneficiaries aged 65 years and older, who were electively hospitalized and underwent carotid artery stenting (CAS; ICD-9-CM procedure code 00.63) or carotid endarterectomy (CEA; ICD-9-CM procedure code 38.12). Among them, we included in the study cohort only those who underwent procedure for the first time, and all observations with subsequent carotid interventions were excluded from the analysis. Symptomatic patients were identified with the ICD-9-CM diagnosis codes 362.34, 435.x, and 781.4 in any diagnosis position. To identify various postoperative complications, we used the following ICD-9-CM diagnosis codes in any of the 9 secondary diagnoses positions: 997.00, 997.01, 997.02, 997.09, 433.11, 434.01, 434.11, and 434.91—for stroke; 997.1, 410.00-410.02, 410.10-410.12, 410.20-410.22, 410.30-410.32, 410.40-410.42, 410.50-410.52, 410.60-410.62, 410.70-410.72, 410.80-410.82, 410.90-410.92, and 427.5—for cardiac complications including myocardial infarction (MI); 997.3x, 480.x, 481, 482.0-482.2, 482.3x, 482.4x, 482.8x, 482.9, 483.x, 484.x, 485, 486, 507.0, 512.1, 518.4, 518.5, 518.81, 518.82— for respiratory complications and pneumonia; 997.5, 584.x, and 593.81—for renal complications including acute renal failure; 038.0, 038.1x, 038.2, 038.3, 038.4x, 038.8, 038.9, 995.91, 995.92, 998.0, 785.52, 996.61, 996.62, 998.59, 999.3x—for sepsis and bloodstream infection; 599.0 and 996.64—for urinary tract infection (UTI); and 998.30-998.32, 998.51, 998.6, and 998.83—for surgical site infection (SSI). Comorbidities in the study population were evaluated with the (Agency for Healthcare Research and Quality (AHRQ)’s Healthcare Cost and Utilization Project (HCUP) comorbidity software, version 3.5 (available at http://www.hcup-us.ahrq.gov/toolssoftware/ comorbidity/comorbidity.jsp#download).
Statistical Analysis All statistical analyses were performed with the SAS software, version 9.2 (SAS Institute, Cary, North Carolina) and a value P < .05 was considered statistically significant. The 30-day, 60-day, and 90-day readmission rates were calculated by dividing the number of patients who were readmitted to the hospital during these time periods after initial discharge by the number of patients who were discharged alive after initial hospitalization and were expressed as a percentage. To evaluate the difference between the 2 groups, we used the chi-square analysis with computing odds ratios (ORs) and 95% confidence intervals (95% CIs). Significant results in bivariate analysis were tested by multivariable logistic regression analysis with adjustment by age, gender, race, type of surgical procedure, postoperative complications, and comorbidities. We also assessed
the difference in the 90-day, readmission-free survival between patients who underwent CAS or CEA with adjusted Cox proportional hazards modeling and Kaplan-Meier survival curves.
Results A total of 235 247 patients with carotid interventions that met inclusive criteria were selected. Among them, the majority (211 118) of patients underwent CEA and only one-tenth (24 129) underwent CAS. Characteristics of the study population are displayed in Table 1. As shown in Table 1, there was no difference in mean age between patients in both the surgical groups. However, age distribution among patients with CAS differed from those with CEA. Proportions of youngest (65-69 years) and oldest (80 years and older) patients undergoing CAS were significantly greater than among patients undergoing CEA (P < .0002), whereas the fraction of patients at age 70 to 79 years was significantly smaller (P < .0002). In both the surgical groups, males predominated over females (P < .0002). We also found racial disparities in utilization of both surgical procedures. Among patients who underwent CAS, the proportion of whites was smaller (P < .0002) and proportions of blacks and Hispanics were greater (P < .0002) than among patients who underwent CEA. There were differences in the rates of some comorbidity diseases between the 2 surgical groups. Patients who underwent CAS were more likely to have diabetes with chronic complications (P ¼ .012), congestive heart failure, peripheral vascular disease, pulmonary circulation disease, and renal failure (P < .0002 for all) and less likely to have chronic pulmonary disease (P ¼ .001), diabetes without chronic complications (P ¼ .025), hypertension, and obesity (P < .0002 for all) than patients with CEA. Symptomatic patients accounted for 2.7% of all study population. A higher rate of symptomatic patients was found among those undergoing CAS than those undergoing CEA (P < .0002). Overall, the hospital readmission rates after CAS were significantly greater than after CEA. We found this within various time intervals after the index discharge. In the bivariate chisquare analysis, the rates of readmissions after CAS and CEA were, respectively, 11.1% and 8.8% during 30 days after discharge, 18.0% and 13.3% during 60 days, and 22.7% and 16.9% during 90 days after the index discharge; P < .0001 for all comparisons. There was no difference in the readmission rates during 30 days after discharge between symptomatic and asymptomatic patients. However, within 60 and 90 days after discharge, asymptomatic patients were more likely to be readmitted to the hospital than symptomatic patients (OR ¼ 1.10; 95% CI 1.02-1.19; P ¼ .008; and OR ¼ 1.10; 95% CI 1.031.17; P ¼ .006, respectively). Because of some variations in patients’ characteristics between the 2 surgical groups, we performed multivariable logistic regression analysis with readmission as an outcome variable of the model and age, gender, race, symptomatic/ asymptomatic status, postoperative complications and comorbidities as predictors of this outcome. The results of this
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
Galin˜anes et al
219
Table 1. Characteristics of the Study Population. Procedures Characteristics Age, years (mean + SD) Age groupsa 65-69 70-74 75-79 80þ Gendera Male Female Racea White Black Hispanic Other Missing Comorbiditiesa Congestive heart failure Coagulopathy Diabetes without chronic complications Diabetes with chronic complications Hypertension Obesity Peripheral vascular disease Pulmonary circulation disease Renal failure Symptomatic patientsa
CAS (N ¼ 24 129)
CEA (N ¼ 211 118)
P Value
75.59 + 7.24
75.58 + 6.73
.0002
43 51 54 61
(20.4) (24.4) (25.8) (29.4)
.0367 .0377 .0393 .0392
14 510 (60.1) 9619 (39.9)
119,627 (56.7) 91 491 (43.3)
.0690 .0690
22 384 (93.08) 932 (3.88) 254 (1.06) 479 (1.98) 80
198 536 (94.35) 6556 (3.12) 1715 (0.82) 3615 (1.71) 696
.0523 .0414 .0249 .0201
2641 (10.95) 210 (0.87) 6288 (26.06) 519 (2.15) 17 440 (72.28) 768 (3.18) 6050 (25.07) 269 (1.11) 2122 (8.79) 826 (3.42)
13 403 1759 56 438 4045 164 606 8586 40 074 1627 12 033 5597
.1642 .0044 .0152 .0163 .0166 .0476 .1474 .0352 .1194 .0449
5284 (21.9) 5498 (22.8) 5813 (24.1) 7534 (31.2)
133 543 489 953
(6.35) (0.83) (26.73) (1.92) (77.97) (4.07) (18.98) (0.77) (5.70) (2.65)
Abbreviations: CAS, and carotid artery stenting; CEA, carotid endarterectomy; SD, standard deviation. a Variables are reported as number of patients (%).
analysis confirmed our previous findings. After risk adjustment, patients who underwent CAS were still more likely to be readmitted to the hospital when compared to their counterparts with CEA within 30 days (OR ¼ 1.21; 95% CI 1.15-1.26; P < .0001), 60 days (OR ¼ 1.34; 95% CI 1.29-1.39; P < .0001) and 90 days after discharge (OR ¼ 1.36; 95% CI 1.31-1.40). In the multivariable analysis, asymptomatic patients compared to symptomatic ones were still more likely to be readmitted within 60 days (OR ¼ 1.12; 95% CI 1.03-1.20; P ¼ .005) and 90 days after discharge (OR ¼ 1.11; 95% CI 1.03-1.18; P ¼ .004). The other predictors of the hospital readmission within studied time intervals were advanced age, female gender, black race and Hispanic ethnicity, the majority of studied comorbid diseases (congestive heart failure, chronic pulmonary disease, coagulopathy, diabetes, peripheral vascular disease, pulmonary circulation disease, renal failure), and various postoperative complications: cardiac, respiratory, and renal complications; sepsis, SSI, and UTI; postoperative stroke. Risk factors for readmission during 90 days after index discharge are presented in Figure 1. Figure 2 presents Kaplan-Meier curves for readmission-free survival of patients during 90 days after discharge from the hospital where CAS or CEA were performed. To perform readmission-free survival analysis with risk adjustment, we
used Cox proportional hazards regression modeling with adjustment by patient’s age, gender, race, comorbidities, symptomatic/asymptomatic status, and postoperative complications and calculated hazard ratios (HR) with 95% CI to examine a cumulative effect of these risk factors on readmission during 90 days after discharge. This analysis also demonstrated a higher readmission frequency after CAS than after CEA (HR ¼ 1.29; 95% CI 1.26-1.32; P < .0001) and among asymptomatic patients versus symptomatic ones (HR ¼ 1.07; 95% CI 1.02-1.12; P ¼ .005). All risk factors for readmission, which were discovered by multivariable logistic regression analysis remained associated with readmission in Cox proportional hazards regression modeling. We evaluated the most frequent principal diagnosis at hospital readmission. Coronary atherosclerosis of native coronary artery was the most frequent cause of readmission after both CAS and CEA, with greater frequency after CAS (P < .0002). The ranks of the other principal diagnoses in the 2 groups slightly varied. Frequencies of congestive heart failure and atherosclerosis of extremities as causes for readmission after CAS were greater than after CEA (P < .0002 and P ¼ .0003, respectively), whereas occlusion and stenosis of carotid artery without cerebral infarction were more frequent reasons for readmission after CEA than after CAS (P < .0002).
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
220
Vascular and Endovascular Surgery 48(3)
Figure 1. Risk factors for readmission during 90 days after index discharge.
Figure 2. Readmission-free survival after carotid endarterectomy (CEA) and carotid artery stenting (CAS).
Discussion Our analysis found an unexpectedly high readmission rates associated with carotid interventions among the Medicare population. Readmission rates (%) for patients undergoing CEA
and CAS, respectively, were 8.84 and 11.11 at 30 days (P < .0001), 13.31 and 17.98 at 60 days (P < .0001), and 16.86 and 22.68 at 90 days (P < .0001). Recently, using the ACS National Surgical Quality Improvement Program (ACS-NSQIP) database, Curran et al identified a 7.5% rate of 30-day readmission
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
Galin˜anes et al
221
among patients undergoing CEA.25 Jackson et al reported a lower 30-day readmission rate of 4.2% for patients undergoing CEA at a single university hospital institution.5 The low readmission rate reported by Jackson et al most likely represents single-institutional bias, as our rates are similar to other large population database analyses. When using large population data sets, readmission for carotid interventions appears to be greater than expected. Using ICD9-CM codes, Kennedy et al was able to identify outcomes of CEAs performed in the State of California and reported a 30day readmission rate of 7% for CEA.6 Stuart et al analyzed surgical databases and observed an 8% rate of readmission after CEA in the United Kingdom.7 Although greater than expected, our analysis of the Medicare & Medicaid data sets demonstrated a 30-day hospital readmission rate of 11% and 8.8% for CAS and CEA, respectively, which appears to be consistent with the current published literature using large population databases. Our results demonstrate a greater likelihood for hospital readmission associated with CAS compared to CEA. After adjusting for confounding factors, patients undergoing CAS were almost at 1.5 times greater risk of readmission than patients undergoing CEA. This risk continued to increase at 60 and 90 days after procedure. Patients who underwent carotid stenting were 1.29 times as likely to be readmitted (P < .0001) compared to those undergoing endarterectomy. Ultimately, our data demonstrate no benefit of an endovascular approach with respect to readmission rates associated with carotid artery interventions. Higher readmission rates among patients undergoing endovascular procedures than open operation have been reported in the literature. Vogel et al reported a 30-day readmission rate of 15.3% in patients undergoing endovascular lower extremity revascularization compared to a rate of 13.9% associated with open procedures.8 In addition, Casey et al demonstrated higher rates of hospital readmission in patients undergoing endovascular abdominal aortic aneurysm repair those going for open repair.9 Our data coincide with the trend of greater readmission rates associated endovascular approaches compared to open surgery. We found the diagnosis of coronary artery disease to be the most common reason for readmission in both the groups. This is consistent with Jencks et al who found cardiac complications to be the most common reason for readmission following surgery and the third most common reason for readmission in patients undergoing vascular surgery following further surgical interventions and amputations.1 This was further suggested by Kind et al who found congestive heart failure to be the most common reason for admission among Medicare beneficiaries between the years 2005 and 2006.10 Using the Society for Vascular Surgery Vascular Registry (SVS-VR), Sidawy et al demonstrated that symptomatic and asymptomatic patients undergoing CAS had significantly higher 30-day postprocedure incidence of death/stroke/MI when than patients undergoing CEA (6.42% vs 2.62%, P < .0001).11 Our results are consistent with those found in the SVS-VR, indicating that in readmission among patients undergoing CAS, medical reasons are more commonly
cited. In comparison, patients undergoing CEA had great rates of readmission attributed to restenosis and occlusion. In the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) trial, repeat revascularization was 4.2% to 5.8% greater in the CEA group but was found to be nonsignificant.4 The largest cohorts of patients being treated in each group were octogenarians comprising approximately 30%. It was also found that these patients had a higher likelihood of being readmitted at all time periods. Kind et al demonstrated a trend toward greater 30-day readmission rates among Medicare beneficiaries with advancing age.10 Patients aged 85 or older had 30-day readmission rate of 25.1% compared to those aged 65 to 69 who had 8% of readmission rate at 30 days. Additionally, it was noted that there was increase in utilization of stents in this group as well. Data from the CREST trial showed that these patients also have a higher stroke rate (almost 12%) with use of CAS.12 These data suggest that octogenarians are a highrisk group of patients and may need more intense pre- and postoperative follow-up. Postoperative complications were found to be significant predictors for readmission. Patients who had a postoperative stroke were 2.8 times as likely to be readmitted (P < .0001), patients who had surgical site infections were 2.4 times as likely to be readmitted (P < .0001), followed by sepsis and UTIs. Kassin et al evaluated 30-day postoperative readmission rates for general surgery patients and found that postoperative complications appear to drive readmissions in surgical patients.13 Our data and findings also support the finding that hospital complications after CEA and CAS are strong predictors of readmission. Finding ways to minimize these complications may significantly improve the readmission rate in our study population. As well, because the rates of stroke after CAS are known to be higher, and stroke was the strongest predictor of readmission, this may account for higher readmission rate after CAS. Comorbidities were also significant predictors of readmission. We have demonstrated that patients with congestive heart failure were 1.6 times as likely to be readmitted, patients with renal failure were 1.6 times as likely to be readmitted, and diabetics were 1.4 times more likely to be readmitted. Previous studies following other vascular-related surgeries and procedures have identified these as risk factors for readmission.14,15 Identifying these patients who are at high risk may allow for better postoperative planning to help prevent readmission. It may be that at the time of discharge those with known risk factors not only follow-up with vascular surgeon and that a structure is in place to follow up with practitioners managing their comorbidities. Accounting for confounders, we were able to identify advanced age (>80), female gender, black and Hispanic ethnicity, and the presence of comorbidities as predictors of readmission. Hannan et al identified similar variables (advanced age, female gender, and black race) as predictors of 30-day readmission after coronary bypass surgery.16 Moreover, in a single-institutional, retrospective study, Jackson et al identified advanced age and diabetes as a predictors of readmission, specifically for vascular procedures (P ¼ .39).5
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
222
Vascular and Endovascular Surgery 48(3)
Strategies need to be implemented for reduction in health care costs in the future, with the current focus of CMS on readmission rates. This can prove to be difficult as the definition of readmission depends on certain circumstances. Vascular surgery is a dynamic field where many procedures can be performed in a ambulatory setting that may require multiple visits in a short period, which collectively aid in the ultimate care of the patient. Jackson et al identified a 3% planned readmission rate accounting for preoperative workups, contralateral lower extremity endovascular revascularization following prior unilateral procedure, or diagnostic angiogram following revascularization.5 Unplanned readmission rates were approximately 8.9%, with surgical causes of readmission (wound infection, hematoma, or revascularization) accounting for two-thirds of those admissions.5 Cardiac and infectious causes accounted for only a third of hospital readmission rates that were unplanned.5 Brooke et al suggested a 4-phase model consisting of patient demographics and procedures, postoperative hospital course, the discharge, and readmission in analyzing readmissions rates, and attempting to identify areas of intervention.17 Many articles, including ours, have identified predictors of readmission targeting the first phase; however, few successful strategies exist to minimize radmission. Wennberg et al have suggested postdischarge telephone calls, while Hernandez et al suggested early clinical follow-up to be successful in decreasing readmission rates.18,19 Despite the implementation of various strategies all along Brookes’ 4-phase model, a retrospective meta-analysis of the available literature suggested that no single intervention implemented alone was regularly associated with reduced risk of 30-day rehospitalization.20 In analysis of the ACS-NSQUIP database, Lawson et al identified postoperative complications as the single most predictive factor in surgical readmissions and an area with most potential for impact.21 This analysis supports these findings with stroke, surgical site infection, respiratory, and cardiac complications, all associated with readmission. With the ubiquitous Patient Protection & Affordable Care Act and its impending financial penalties on readmission rates, it seems evident based on the readmission rates that CEA is superior to CAS on a cost–benefit prospective. Using a hypothetical cohort model and Medicare costs, Young et al found a 59% probability that CEA would become the procedure of choice based on lifetime expenditure.22 The CEA was associated with a lifetime cost of US$35 200 compared to US$52 900 for CAS. Kilaru et al concluded similar results suggesting that in order for CAS to be fiscally comparable, the mortality and major stroke rates of CAS must be at least equivalent to if not less than those of CEA.23 This analysis has several limitations. Ideally, a doubleblinded randomized control study would be the preferred methodology to assess cause and relationship; however, our retrospective analysis can provide insight and direction for further investigations. Furthermore, our study is limited by data acquisition relying on administrative codes. The Medicare data are an administrative database and clinical information may be limited by the ICD-9-CM and CPT codes with
respect to definition of indications and coding that could vary between institutions and coders. In addition, certain complications may not be captured in administrative data sets. Refined clinical data are not possible from administrative data; however, this study describes rates of procedures and readmission on thousands of Medicare patients. Another limitation is that confounding by indication may occur, as the study is not randomized. Indications for treatment may be biased in relation to future health outcomes. Sicker patients may have been preferentially treated with less invasive procedures skewing results. Goodney et al, using the MEDPAR database for 1994 to 1999, found a 30-day hospital readmission rates for high-risk patients undergoing CEA to be 11% comparable to our 11% readmission rates for CAS.24 In our analysis, patients undergoing CAS had greater number of comorbidities and perhaps were more representative of the patient population analyzed by Goodney et al previously when CAS was not routinely performed. These results also suggest that hospital readmission rates are more attributed to patient population and less a factor of surgical approach. Nonetheless, after risk adjustment, patients who underwent CAS were still more likely to be readmitted to the hospital when compared to their counterparts with CEA within 30 days, 60 days, and 90 days after discharge. In conclusion, our data demonstrate a high readmission rate for patients undergoing carotid intervention. It may be that while as surgeons we perceive these cases as minimally invasive and some of the lower risk surgery performed, these patients’ comorbidities may not be as well optimized as possible pre- and postoperatively, contributing to the high readmission rate. Identifying predictors of readmission is essential to help improve outcomes. By understanding the risk factors that predispose readmission, these patients can be targeted for better postoperative care. In addition, postoperative complications continue to drive readmissions in surgical patients, and continued efforts to minimize these complications must still be a goal. In addition, patients who undergo CAS must be chosen carefully, as a less invasive procedure does not always mean lower complications as seen by their higher readmission rate. Further evaluation is warranted into hospital readmission after carotid intervention to help further ascertain ways to decrease the readmission rate. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
References 1. Jencks SF, Williams MV, Coleman EA. Rehospitalizations among patients in the Medicare fee-for-service program. N Engl J Med. 2009;360(14):1418-1428. 2. Anderson PL, Gelijns A, Moskowitz A, et al. Understanding trends in inpatient surgical volume: vascular interventions, 1980-2000. J Vasc Surg. 2004;39(6):1200-1208.
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
Galin˜anes et al
223
3. Brott TG, Hobson RW 2nd, Howard G, et al. Stenting versus endarterectomy for treatment of carotid-artery stenosis. N Engl J Med. 2010;363(1):11-23. 4. Mantese VA, Timaran CH, Chiu D, Begg RJ, Brott TG. The carotid revascularization endarterectomy versus stenting trial (CREST): stenting versus carotid endarterectomy for carotid disease. Stroke. 2010;41(10 suppl):S31-S34. 5. Jackson BM, Nathan DP, Doctor L, Wang GJ, Woo EY, Fairman RM. Low rehospitalization rate for vascular surgery patients. J Vasc Surg. 2011;54(3):767-772. 6. Kennedy BS, Fortmann SP, Stafford RS. Elective and isolated carotid endarterectomy: health disparities in utilization and outcomes, but not readmission. J Natl Med Assoc. 2007;99(5):480-488. 7. Stuart WP, Hussey KK, Eifell RK, Drummond R, Ford I, Welch GH. Using centrally held data to validate carotid surgery outcome data. Stroke. 2013;44(6):1670-1675. 8. Vogel TR, Kruse RL. Risk factors for readmission after lower extremity procedures for peripheral artery disease. J Vasc Surg. 2013;58(1):90-97.e1-e4. 9. Casey K, Hernandez-Boussard T, Mell MW, Lee JT. Differences in readmissions after open repair versus endovascular aneurysm repair. J Vasc Surgery. 2013;57(1):89-95. 10. Kind AJ, Bartels C, Mell MW, Mullahy J, Smith M. For-profit hospital status and rehospitalizations at different hospitals: an analysis of Medicare data. Ann Intern Med. 2010;153(11):718-727. 11. Sidawy AN, Zwolak RM, White RA, Siami FS, Schermerhorn ML, Sicard GA. Risk-adjusted 30-day outcomes of carotid stenting and endarterectomy: results from the SVS Vascular Registry. J Vasc Surg. 2009;49(1):71-79. 12. Hobson RW 2nd, Howard VJ, Roubin GS, et al. Carotid artery stenting is associated with increased complications in octogenarians: 30-day stroke and death rates in the CREST lead-in phase. J Vasc Surg. 2004;40(6):1106-1111. 13. Kassin MT, Owen RM, Perez SD, et al. Risk factors for 30-day hospital readmission among general surgery patients. J Am Coll Surg. 2012;215(3):322-330. 14. Stewart RD, Campos CT, Jennings B, Lollis SS, Levitsky S, Lahey SJ. Predictors of 30-day hospital readmission after coronary artery bypass. Ann Thorac Surg. 2000;70(1):169-174.
15. Vogel TR, Dombrovskiy VY, Carson JL, Graham AM. Inhospital and 30-day outcomes after tibioperoneal interventions in the US Medicare population with critical limb ischemia. J Vasc Surg. 2011;54(1):109-115. 16. Hannan EL, Racz MJ, Walford G, et al. Predictors of readmission for complications of coronary artery bypass graft surgery. JAMA. 2003;290(6):773-780. 17. Brooke BS, De Martino RR, Girotti M, Dimick JB, Goodney PP. Developing strategies for predicting and preventing readmissions in vascular surgery. J Vasc Surg. 2012;56(2):556-562. 18. Wennberg DE, Marr A, Lang L, O’Malley S, Bennett G. A randomized trial of a telephone care-management strategy. N Engl J Med. 2010;363(13):1245-1255. 19. Hernandez AF, Greiner MA, Fonarow GC, et al. Relationship between early physician follow-up and 30-day readmission among Medicare beneficiaries hospitalized for heart failure. JAMA. 2010;303(17):1716-1722. 20. Hansen LO, Young RS, Hinami K, Leung A, Williams MV. Interventions to reduce 30-day rehospitalization: a systematic review. Ann Intern Med. 2011;155(8):520-528. 21. Lawson EH, Lee Hall B, Louie R, et al. Association between occurrence of a postoperative complication and readmission: implications for quality improvement and cost savings. Ann Surg. 2013;258(1):10-18. 22. Young KC, Holloway RG, Burgin WS, Benesch CG. A costeffectiveness analysis of carotid artery stenting compared with endarterectomy. J Stroke Cerebrovasc Dis. 2010;19(5): 404-409. 23. Kilaru S, Korn P, Kasirajan K, et al. Is carotid angioplasty and stenting more cost effective than carotid endarterectomy? J Vasc Surg. 2003;37(2):331-339. 24. Goodney PP, Stukel TA, Lucas FL, Finlayson EV, Birkmeyer JD. Hospital volume, length of stay, and readmission rates in high-risk surgery. Ann Surg. 2003;238(2):161-167. 25. Curran T, Lo RC, Fokkema M, Wyers M, Hamdan A, Chaikof E, Schermerhorn ML. Predictors of 30-Day Readmission and Post-Discharge Mortality Following Carotid Endarterectomy in the ACS-NSQIP. Journal of Vascular Surgery. 2013; 57(5):93S-94S.
Downloaded from ves.sagepub.com at UNIV OF CALIFORNIA SANTA CRUZ on March 31, 2015
