Hospital procedure volume should not be used as a measure of surgical quality

Abstract

Introduction: The Agency for Healthcare Research and Quality and the Leapfrog Group use hospital procedure volume as a quality measure for pancreatic resection (PR), abdominal aortic aneurysm (AAA) repair, esophageal resection (ER), and coronary artery bypass grafting (CABG). However, controversy exists regarding the strength and validity of the evidence for the volume-outcome association. The purpose of this study was to reevaluate the volume-outcome relationship for these procedures.

Methods: Discharge data for 261,412 patients were extracted from the 2008 Nationwide Inpatient Sample. The relationship between hospital procedure volume and mortality was rigorously assessed using hierarchical general linear modeling with restricted cubic splines, adjusted for patient demographics, comorbid disease, and elective procedure status.

Results: Unadjusted mortality rates were PR (4.7%), AAA (12.7%), ER (5.8%), and CABG (2.2%), and the majority of operations were elective. Hospital procedure volume was not a statistically significant predictor of in-hospital mortality for any of the 4 procedures. Strong predictors of mortality included age, elective procedure status, renal failure, and malnutrition (P < 0.001). Each of the models demonstrated excellent performance in estimating the probability of death.

Conclusions: Hospital procedure volume is not a significant predictor of mortality for the performance of pancreatectomy, AAA repair, esophagectomy, or CABG. Procedure volume by itself should not be used as a proxy measure for surgical quality. Patient mortality risk is primarily attributable to patient-level characteristics such as age and comorbidity.