ORIGINAL ARTICLE
Trends in the Frequency and Quality of Parathyroid Surgery Analysis of 17,082 Cases Over 10 Years Amer G. Abdulla, MS, Philip H. G. Ituarte, PhD, MPH, Avital Harari, MD, James X. Wu, MD, and Michael W. Yeh, MD
Objective: To examine trends in the frequency and quality of surgery for primary hyperparathyroidism (PHPT) in California during the period of 1999 to 2008. Background: The quality of surgery for PHPT can be measured by the complication rate and the success rate of surgery. A fraction of patients with failed initial surgery undergo reoperation. Methods: Data on patients undergoing parathyroidectomy (PTx) were obtained from the California Office of Statewide Health Planning and Development. Renal transplant recipients and dialysis patients were excluded. Hospitals were categorized by case volume: Very low: 1 to 4 operations annually; Low: 5 to 9; Medium, 10 to 19; High: 20 to 49; Very high: 50 or more. Complication rates and the percentage of cases requiring reoperation were analyzed. Results: A total of 17,082 cases were studied. Annual case volume grew from 990 to 2746 (177% increase) over the study period, corresponding to a 147% increase in the per capita PTx rate. The proportion of cases performed by very high-volume hospitals increased from 6.4% to 20.5% (P < 0.001). The overall complication rate declined from 8.7% to 3.8% (P < 0.001). Complication rates were inversely related to hospital volume (very high volume, 3.9% vs very low volume, 5.2%, P < 0.05). Reoperation was performed in 363 patients (2.1%). The reoperation rate increased from 0.91% to 2.73% during the study period (P < 0.01). The reoperation rate was inversely and nonlinearly related to hospital volume, as described by the equation % reoperation = 100/(total hospital case volume). Conclusions: Surgery for PHPT has grown safer and more common over time. High-volume centers have lower rates of complication and reoperation. Keywords: complications, outcomes, primary hyperparathyroidism, quality, reoperation (Ann Surg 2015;261:746–750)
P
rimary hyperparathyroidism (PHPT) is a condition characterized by one or more hypersecreting parathyroid glands, resulting in hypercalcemia and consequent diseases of bone and mineral metabolism.1 The incidence of PHPT has tripled in the past 10 years. Today, 1 in 400 women and 1 in 1200 men are affected.2 The only curative treatment is surgical removal of the abnormal gland(s). There has been a steady increase in the number of patients undergoing parathyroidectomy (PTx) both in the United States and worldwide,3,4 which From the Section of Endocrine Surgery, UCLA David Geffen School of Medicine, Los Angeles, CA. Disclosure: Research supported in part by the H&H Lee Surgical Research Scholars Program. The authors declare no conflicts of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.annalsofsurgery.com). Reprints: Michael W. Yeh, MD, Department of Surgery and Medicine, Section of Endocrine Surgery, UCLA David Geffen School of Medicine, 10833 Le Conte Avenue, 72-228 CHS, Los Angeles, CA 90095. E-mail: [email protected] C 2014 Wolters Kluwer Health, Inc. All rights reserved. Copyright ISSN: 0003-4932/14/26104-0746 DOI: 10.1097/SLA.0000000000000812
746 | www.annalsofsurgery.com
has been attributed to (1) a growing elderly population in which the incidence of PHPT is highest5 ; (2) enhanced imaging techniques and more frequent testing of blood calcium levels, leading to an increase in PHPT diagnoses3,6 ; (3) well-defined consensus indications for PTx in asymptomatic patients7 ; and (4) the rise of outpatient PTx.3,8 High-volume centers are known to deliver superior outcomes in endocrine surgery, as measured by reduced complication and mortality rates, reduced length of stay, and reduced risk of avoidable reoperation.9–13 This descriptive study was undertaken to examine trends in the frequency and quality of surgery for PHPT in California. Specifically, we sought to describe (1) trends in the frequency of PTx and the degree of case concentration with high-volume centers, (2) trends in complication rates by year and by hospital volume, and (3) patterns in the percentage of patients requiring reoperation for persistent or recurrent PHPT by year and by hospital volume.
METHODS The California Office of Statewide Health Planning and Development (OSHPD) tracks data originating from the population of all Californians who were hospitalized at non-Federal, non-prison inpatient settings from 1999 through 2008, and all Californians treated at non-Federal, non-prison ambulatory surgery centers from 2005 to 2008. This population data set was searched to identify all patients who had any endocrine procedure (thyroid, parathyroid, adrenal, etc.) between 1999 and 2008 in either an inpatient or ambulatory setting. The data were further searched to identify all cases that specifically had International Classification of Diseases, Ninth Revision (ICD-9) or current procedural terminology (CPT) procedure codes associated with PTx procedures. The OSHPD data set includes unique patient identifiers, permitting identification of reoperative cases. For inpatient records, the data set included a primary diagnosis with up to 24 other ICD-9 Clinical Modification (ICD-9-CM) diagnosis codes. Similarly, each admission included a primary procedure with up to 19 other ICD-9-CM procedure codes. For ambulatory records, ICD9-CM diagnosis codes were also used, but CPT codes were used to identify procedures performed. Using corresponding ICD-9-CM codes, patients with a history of renal failure, kidney transplant, or dialysis were excluded from analysis. Comorbidity scores were created by applying the Deyo modification of the Charlson comorbidity scale.14,15 Race was coded as white, Hispanic, black, Asian, or other. Insurance status was coded as private/HMO, Medicare, Medi-Cal/indigent/self-pay, VA, or other government agency. Hospital volume was defined as the mean number of PTx cases performed per year over the 10-year study period. Hospital volume was categorized into 5 groups, corresponding to rough quintiles: very low (1–4 procedures per year), low (5–9), medium (10–19), high (20– 49), and very high (≥50). Complications were assessed as either surgical or medical as previously described,16 with each patient being classified as having had either (a) no complications or (b) 1 or more complications within 30 days of surgery. Surgical complications included hemorrhage, hypocalcemia, airway complications (eg, requiring tracheostomy), Annals of Surgery r Volume 261, Number 4, April 2015
Copyright © 2014 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
Annals of Surgery r Volume 261, Number 4, April 2015
respiratory complications (eg, aspiration), cerebrovascular accidents, vocal cord paralysis, and wound complications. Medical complications included anesthesia-related events, cardiovascular events, deep vein thrombosis, pulmonary embolism, renal-related events, sepsis, and urinary tract infections. Complications were collected by searching for relevant ICD-9 or CPT codes associated with complications during the hospital stay associated with the patients’ admission for PTx. Searching patient discharge records for additional episodes of PTx after initial PTx identified reoperations for PHPT.
STATISTICAL ANALYSIS Demographics, annual trends, and hospital volume effects were studied using univariate descriptive statistics including contingency table analysis and 1-way analysis of variance. To study factors associated with complications, we applied multivariable, stepwise logistic regression analyses. Complications were coded as none versus 1 or more complications for a given admission. To model complications, we applied backward elimination and set the criterion to remain in the model at P ≤ 0.10. The following covariates were included in the model: age, sex, race, comorbidity score, insurance status, inpatient vs ambulatory setting, and year of surgery. All data were analyzed using Stata/SE 12.1 statistical analysis software (Stata Corp, College Station, TX).
RESULTS The OSHPD data yielded 17,082 PTx cases performed on 16,719 unique patients across 349 hospitals. Patient demographics are summarized in Table 1. The average age at time of surgery was 60 years. The majority of patients were female (74.5%) and white (73.8%). The study population was disproportionately white in comparison to the overall California state population, which is 53% white.
Surgery for Hyperparathyroidism
The majority of patients had zero comorbidities (77.2%) and private health insurance (56.6%). The number of PTx cases rose annually, increasing 177% from 990 cases in 1999 to 2746 in 2008 (Fig. 1A). Similarly, the per capita PTx rate for the state increased 147% from 2.93 to 7.25 per 100,000 residents. The outpatient case volume grew from 542 (24.1%) in 2005 to 1301 (47.4%) in 2008. When patient age was considered, the volume of PTx cases grew across all age categories (Fig. 1B), with the greatest increases observed among patients aged 50 to 59 (180% increase) and 60 to 69 (231% increase) years. When trends in PTx frequency were assessed in relation to the publication of the revised consensus guidelines on asymptomatic PHPT in 2002,7 no differences were found in comparing the period before 2002 to the period 2002 to 2008. No time-related changes were noted in patient demographics, comorbidity scores, or insurance status. Hospital volume categories, chosen to correspond approximately to quintiles for the sake of simplicity, displayed modest clustering of cases among the 3 middle categories (very low volume, n = 2690; 15.2%; low, n = 115, 23.3%; medium, n = 4759, 26.9%; high, n = 3573, 20.3%; very high, n = 2493, 14.3%). Over the study period, the proportion of cases performed by very high-volume hospitals increased from 6.4% to 20.5% (P < 0.001), whereas the proportion performed by low and very low-volume hospitals decreased from 50% to 38% (P < 0.001, Fig. 2). Overall complication rates declined over time (Fig. 3A), attributable to a decline in both surgical and medical complications (Figs. 3B, C; supplemental Table 1, available at http://links.lww.com/ SLA/A579). The average composite complication rate declined from 8.7% to 3.8% from 1999 to 2008 (P < 0.001). In univariate analyses, when surgical and medical complications were analyzed separately, each declined by 66.7% (P < 0.001) and 66.7% (P = 0.009), respectively. Higher volume hospitals encountered significantly fewer total complications compared with lower volume centers (P = 0.03),
TABLE 1. Demographic Information Across Study Period (n = 17,082) Inpatient (n = 13,911)
Variable Age, mean (SD), yr Sex, frequency (%) Women Men Race, frequency (%) White Hispanic Black Asian Other Comorbidity score, frequency (%) 0 1 2 ≥3 Insurance status, frequency (%) Private insurance or HMO Medicare Medi-Cal or indigent VA or other government Facility size (cases/yr), frequency (%) 1–4 5–9 10–19 20–49 ≥50 Reoperation status, frequency (%) Single procedure Reoperation
Ambulatory (n = 3171)
60.1 (13.9)
59.5 (13.0)
10,362 (74.5) 3549 (25.5)
2359 (74.4) 812 (25.6)
10,116 (72.7) 1745 (12.5) 899 (6.5) 729 (5.2) 422 (3.0)
2495 (78.7) 82 (2.6) 177 (5.6) 165 (5.2) 252 (7.9)
10,585 (76.1) 2774 (19.9) 475 (3.4) 77 (0.6)
2595 (81.8) 487 (15.4) 80 (2.5) 9 (0.3)
7375 (53.0) 5414 (38.9) 967 (7.0) 155 (1.1)
2289 (72.2) 691 (21.8) 164 (5.2) 27 (0.8)
2182 (15.7) 3274 (23.5) 3752 (27.0) 2742 (19.7) 1961 (14.1)
420 (13.3) 711 (22.4) 847 (26.7) 717 (22.6) 476 (15.0)
13,615 (97.9) 296 (2.1)
3104 (97.9) 67 (2.1)
P
Total
0.028 0.912
Trends in the Frequency and Quality of Parathyroid Surgery Analysis of 17,082 Cases Over 10 Years Amer G. Abdulla, MS, Philip H. G. Ituarte, PhD, MPH, Avital Harari, MD, James X. Wu, MD, and Michael W. Yeh, MD
Objective: To examine trends in the frequency and quality of surgery for primary hyperparathyroidism (PHPT) in California during the period of 1999 to 2008. Background: The quality of surgery for PHPT can be measured by the complication rate and the success rate of surgery. A fraction of patients with failed initial surgery undergo reoperation. Methods: Data on patients undergoing parathyroidectomy (PTx) were obtained from the California Office of Statewide Health Planning and Development. Renal transplant recipients and dialysis patients were excluded. Hospitals were categorized by case volume: Very low: 1 to 4 operations annually; Low: 5 to 9; Medium, 10 to 19; High: 20 to 49; Very high: 50 or more. Complication rates and the percentage of cases requiring reoperation were analyzed. Results: A total of 17,082 cases were studied. Annual case volume grew from 990 to 2746 (177% increase) over the study period, corresponding to a 147% increase in the per capita PTx rate. The proportion of cases performed by very high-volume hospitals increased from 6.4% to 20.5% (P < 0.001). The overall complication rate declined from 8.7% to 3.8% (P < 0.001). Complication rates were inversely related to hospital volume (very high volume, 3.9% vs very low volume, 5.2%, P < 0.05). Reoperation was performed in 363 patients (2.1%). The reoperation rate increased from 0.91% to 2.73% during the study period (P < 0.01). The reoperation rate was inversely and nonlinearly related to hospital volume, as described by the equation % reoperation = 100/(total hospital case volume). Conclusions: Surgery for PHPT has grown safer and more common over time. High-volume centers have lower rates of complication and reoperation. Keywords: complications, outcomes, primary hyperparathyroidism, quality, reoperation (Ann Surg 2015;261:746–750)
P
rimary hyperparathyroidism (PHPT) is a condition characterized by one or more hypersecreting parathyroid glands, resulting in hypercalcemia and consequent diseases of bone and mineral metabolism.1 The incidence of PHPT has tripled in the past 10 years. Today, 1 in 400 women and 1 in 1200 men are affected.2 The only curative treatment is surgical removal of the abnormal gland(s). There has been a steady increase in the number of patients undergoing parathyroidectomy (PTx) both in the United States and worldwide,3,4 which From the Section of Endocrine Surgery, UCLA David Geffen School of Medicine, Los Angeles, CA. Disclosure: Research supported in part by the H&H Lee Surgical Research Scholars Program. The authors declare no conflicts of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.annalsofsurgery.com). Reprints: Michael W. Yeh, MD, Department of Surgery and Medicine, Section of Endocrine Surgery, UCLA David Geffen School of Medicine, 10833 Le Conte Avenue, 72-228 CHS, Los Angeles, CA 90095. E-mail: [email protected] C 2014 Wolters Kluwer Health, Inc. All rights reserved. Copyright ISSN: 0003-4932/14/26104-0746 DOI: 10.1097/SLA.0000000000000812
746 | www.annalsofsurgery.com
has been attributed to (1) a growing elderly population in which the incidence of PHPT is highest5 ; (2) enhanced imaging techniques and more frequent testing of blood calcium levels, leading to an increase in PHPT diagnoses3,6 ; (3) well-defined consensus indications for PTx in asymptomatic patients7 ; and (4) the rise of outpatient PTx.3,8 High-volume centers are known to deliver superior outcomes in endocrine surgery, as measured by reduced complication and mortality rates, reduced length of stay, and reduced risk of avoidable reoperation.9–13 This descriptive study was undertaken to examine trends in the frequency and quality of surgery for PHPT in California. Specifically, we sought to describe (1) trends in the frequency of PTx and the degree of case concentration with high-volume centers, (2) trends in complication rates by year and by hospital volume, and (3) patterns in the percentage of patients requiring reoperation for persistent or recurrent PHPT by year and by hospital volume.
METHODS The California Office of Statewide Health Planning and Development (OSHPD) tracks data originating from the population of all Californians who were hospitalized at non-Federal, non-prison inpatient settings from 1999 through 2008, and all Californians treated at non-Federal, non-prison ambulatory surgery centers from 2005 to 2008. This population data set was searched to identify all patients who had any endocrine procedure (thyroid, parathyroid, adrenal, etc.) between 1999 and 2008 in either an inpatient or ambulatory setting. The data were further searched to identify all cases that specifically had International Classification of Diseases, Ninth Revision (ICD-9) or current procedural terminology (CPT) procedure codes associated with PTx procedures. The OSHPD data set includes unique patient identifiers, permitting identification of reoperative cases. For inpatient records, the data set included a primary diagnosis with up to 24 other ICD-9 Clinical Modification (ICD-9-CM) diagnosis codes. Similarly, each admission included a primary procedure with up to 19 other ICD-9-CM procedure codes. For ambulatory records, ICD9-CM diagnosis codes were also used, but CPT codes were used to identify procedures performed. Using corresponding ICD-9-CM codes, patients with a history of renal failure, kidney transplant, or dialysis were excluded from analysis. Comorbidity scores were created by applying the Deyo modification of the Charlson comorbidity scale.14,15 Race was coded as white, Hispanic, black, Asian, or other. Insurance status was coded as private/HMO, Medicare, Medi-Cal/indigent/self-pay, VA, or other government agency. Hospital volume was defined as the mean number of PTx cases performed per year over the 10-year study period. Hospital volume was categorized into 5 groups, corresponding to rough quintiles: very low (1–4 procedures per year), low (5–9), medium (10–19), high (20– 49), and very high (≥50). Complications were assessed as either surgical or medical as previously described,16 with each patient being classified as having had either (a) no complications or (b) 1 or more complications within 30 days of surgery. Surgical complications included hemorrhage, hypocalcemia, airway complications (eg, requiring tracheostomy), Annals of Surgery r Volume 261, Number 4, April 2015
Copyright © 2014 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
Annals of Surgery r Volume 261, Number 4, April 2015
respiratory complications (eg, aspiration), cerebrovascular accidents, vocal cord paralysis, and wound complications. Medical complications included anesthesia-related events, cardiovascular events, deep vein thrombosis, pulmonary embolism, renal-related events, sepsis, and urinary tract infections. Complications were collected by searching for relevant ICD-9 or CPT codes associated with complications during the hospital stay associated with the patients’ admission for PTx. Searching patient discharge records for additional episodes of PTx after initial PTx identified reoperations for PHPT.
STATISTICAL ANALYSIS Demographics, annual trends, and hospital volume effects were studied using univariate descriptive statistics including contingency table analysis and 1-way analysis of variance. To study factors associated with complications, we applied multivariable, stepwise logistic regression analyses. Complications were coded as none versus 1 or more complications for a given admission. To model complications, we applied backward elimination and set the criterion to remain in the model at P ≤ 0.10. The following covariates were included in the model: age, sex, race, comorbidity score, insurance status, inpatient vs ambulatory setting, and year of surgery. All data were analyzed using Stata/SE 12.1 statistical analysis software (Stata Corp, College Station, TX).
RESULTS The OSHPD data yielded 17,082 PTx cases performed on 16,719 unique patients across 349 hospitals. Patient demographics are summarized in Table 1. The average age at time of surgery was 60 years. The majority of patients were female (74.5%) and white (73.8%). The study population was disproportionately white in comparison to the overall California state population, which is 53% white.
Surgery for Hyperparathyroidism
The majority of patients had zero comorbidities (77.2%) and private health insurance (56.6%). The number of PTx cases rose annually, increasing 177% from 990 cases in 1999 to 2746 in 2008 (Fig. 1A). Similarly, the per capita PTx rate for the state increased 147% from 2.93 to 7.25 per 100,000 residents. The outpatient case volume grew from 542 (24.1%) in 2005 to 1301 (47.4%) in 2008. When patient age was considered, the volume of PTx cases grew across all age categories (Fig. 1B), with the greatest increases observed among patients aged 50 to 59 (180% increase) and 60 to 69 (231% increase) years. When trends in PTx frequency were assessed in relation to the publication of the revised consensus guidelines on asymptomatic PHPT in 2002,7 no differences were found in comparing the period before 2002 to the period 2002 to 2008. No time-related changes were noted in patient demographics, comorbidity scores, or insurance status. Hospital volume categories, chosen to correspond approximately to quintiles for the sake of simplicity, displayed modest clustering of cases among the 3 middle categories (very low volume, n = 2690; 15.2%; low, n = 115, 23.3%; medium, n = 4759, 26.9%; high, n = 3573, 20.3%; very high, n = 2493, 14.3%). Over the study period, the proportion of cases performed by very high-volume hospitals increased from 6.4% to 20.5% (P < 0.001), whereas the proportion performed by low and very low-volume hospitals decreased from 50% to 38% (P < 0.001, Fig. 2). Overall complication rates declined over time (Fig. 3A), attributable to a decline in both surgical and medical complications (Figs. 3B, C; supplemental Table 1, available at http://links.lww.com/ SLA/A579). The average composite complication rate declined from 8.7% to 3.8% from 1999 to 2008 (P < 0.001). In univariate analyses, when surgical and medical complications were analyzed separately, each declined by 66.7% (P < 0.001) and 66.7% (P = 0.009), respectively. Higher volume hospitals encountered significantly fewer total complications compared with lower volume centers (P = 0.03),
TABLE 1. Demographic Information Across Study Period (n = 17,082) Inpatient (n = 13,911)
Variable Age, mean (SD), yr Sex, frequency (%) Women Men Race, frequency (%) White Hispanic Black Asian Other Comorbidity score, frequency (%) 0 1 2 ≥3 Insurance status, frequency (%) Private insurance or HMO Medicare Medi-Cal or indigent VA or other government Facility size (cases/yr), frequency (%) 1–4 5–9 10–19 20–49 ≥50 Reoperation status, frequency (%) Single procedure Reoperation
Ambulatory (n = 3171)
60.1 (13.9)
59.5 (13.0)
10,362 (74.5) 3549 (25.5)
2359 (74.4) 812 (25.6)
10,116 (72.7) 1745 (12.5) 899 (6.5) 729 (5.2) 422 (3.0)
2495 (78.7) 82 (2.6) 177 (5.6) 165 (5.2) 252 (7.9)
10,585 (76.1) 2774 (19.9) 475 (3.4) 77 (0.6)
2595 (81.8) 487 (15.4) 80 (2.5) 9 (0.3)
7375 (53.0) 5414 (38.9) 967 (7.0) 155 (1.1)
2289 (72.2) 691 (21.8) 164 (5.2) 27 (0.8)
2182 (15.7) 3274 (23.5) 3752 (27.0) 2742 (19.7) 1961 (14.1)
420 (13.3) 711 (22.4) 847 (26.7) 717 (22.6) 476 (15.0)
13,615 (97.9) 296 (2.1)
3104 (97.9) 67 (2.1)
P
Total
0.028 0.912
