Association between hospital and surgeon procedure volume and outcomes of total hip replacement in the United States Medicare population

Background: The mortality and complication rates of many surgical procedure s are inversely related to hospital procedure volume. The objective of this study was to determine whether the volumes of primary and revision total h ip replacements performed at hospitals and by surgeons are associated with rates of mortality and complications. Methods: We analyzed claims data of Medicare recipients who underwent elect ive primary total hip replacement (58,521 procedures) or revision total hip replacement (12,956 procedures) between July 1995 and June 1996. We assess ed the relationship between surgeon and hospital procedure volume and morta lity, dislocation, deep infection, and pulmonary embolus in the first ninet y days postoperatively. Analyses were adjusted for age, gender, arthritis d iagnosis, comorbid conditions, and income. Analyses of hospital volume were adjusted for surgeon volume, and analyses of surgeon volume were adjusted for hospital volume. Results: Twelve percent of all primary total hip replacements and 49% of al l revisions were performed in centers in which ten or fewer of these proced ures were carried out in the Medicare population annually. In addition, 52% of the primary total hip replacements and 77% of the revisions were perfor med by surgeons who carried out ten or fewer of these procedures annually. Patients treated with primary total hip replacement in hospitals in which m ore than 100 of the procedures were performed per year had a lower risk of death than those treated with primary replacement in hospitals in which ten or fewer procedures were performed per year (mortality rate, 0.7% compared with 1.3%; adjusted odds ratio, 0.58; 95% confidence interval, 0.38, 0.89) . Patients treated with primary total hip replacement by surgeons who perfo rmed more than fifty of those procedures in Medicare beneficiaries per year had a lower risk of dislocation than those who were treated by surgeons wh o performed five or fewer of the procedures per year (dislocation rate, 1.5 % compared with 4.2%; adjusted odds ratio, 0.49; 95% confidence interval, 0 .34, 0.69). Patients who had revision total hip replacement done by surgeon s who performed more than ten such procedures per year had a lower rate of mortality than patients who were treated by surgeons who performed three or fewer of the procedures per year (mortality rate, 1.5% compared with 3.1%; adjusted odds ratio, 0.65; 95% confidence interval, 0.44, 0.96). Conclusions: Patients treated at hospitals and by surgeons with higher annu al caseloads of primary and revision total hip replacement had lower rates of mortality and of selected complications. These analyses of Medicare clai ms are limited by a lack of key clinical information such as operative deta ils and preoperative functional status.