RISK ADJUSTMENT OF THE POSTOPERATIVE MORBIDITY RATE FOR THE COMPARATIVE-ASSESSMENT OF THE QUALITY OF SURGICAL CARE - RESULTS OF THE NATIONAL VETERANS AFFAIRS SURGICAL RISK STUDY

Background: The National Veterans Affairs Surgical Risk Study was desi gned to collect reliable, valid data on patient risk and outcomes for major surgery in the Veterans Health Administration and to report comp arative risk-adjusted postoperative mortality and morbidity rates for surgical services in the Veterans Health Administration. Study Design: This was a cohort study conducted at 44 Veterans Affairs Medical Cent ers closely affiliated with university medical centers. Included were 87,078 major noncardiac operations performed under general, spinal, or epidural anesthesia between October 1, 1991, and December 31, 1993. T he main outcomes measures in this report are 21 postoperative adverse events (morbidities) occurring within 30 days after the index procedur e. Multivariable logistic regression risk-adjustment models for all op erations and for eight surgical subspecialties were developed, Results : Patient risk factors predictive of postoperative morbidity included serum albumin level, American Society of Anesthesia class, the complex ity of the operation, and 17 other preoperative risk variables. Wide v ariation in the unadjusted rates of one or more postoperative morbidit ies for all operations was observed across the 44 hospitals (7.4-28.4% ). Risk-adjusted observed-to-expected ratios ranged from 0.49 to 1.46. The Spearman rank order correlation between the ranking of the hospit als based on unadjusted morbidity rates and risk-adjusted observed-to- expected ratios for all operations was 0.87. There was little or no co rrelation between the rank order of the hospitals by risk-adjusted mor bidity and risk-adjusted mortality. Conclusions: The Department of Vet erans Affairs has successfully implemented a system for the prospectiv e collection and comparative reporting of postoperative mortality and morbidity rates after major noncardiac operations. Risk adjustment had only a modest effect on the rank order of the hospitals. (C) 1997 by the American College of Surgeons.