Impact of Hospital Volume on Postoperative Complications and In-hospital Mortality After Renal Surgery: Data From the Japanese Diagnosis Procedure Combination Database

Abstract

Previous studies on the relationship between nephrectomy volume and outcomes focused mainly on operative mortality. Little is known about the association between operative volume and postoperative complications. This study analyzed the influence of hospital volume on postoperative complications and in-hospital mortality after nephrectomy or nephroureterectomy. Using the Diagnosis Procedure Combination database in Japan, 7988 patients undergoing nephrectomy or nephroureterectomy between July and December in 2006 and 2007 were identified. The cases were divided into low (≤26/y), medium (27-64), or high (≥65) hospital volume groups. Logistic regression analyses were performed to model the concurrent effects of hospital volume and other factors on postoperative complications and in-hospital mortality. In-hospital mortality was 0.84%. The overall postoperative complication rate was 7.4%. Factors associated with mortality or morbidity were age, hypertension, chronic lung diseases, cardiac diseases, chronic renal failure, and duration of anesthesia. Video-assisted surgery showed a significantly lower rate of mortality (odds ratio [OR], 0.28; P <.01) and postoperative complications (OR, 0.47; P <.01) than open surgery. The difference of mortality between high and low-volume groups was not significant (0.5% vs 1.0%) (OR, 0.48; P = .089). Although higher hospital volume was associated with fewer postoperative complications (OR, 0.72; P = .014), the difference was slight (7.1% vs 7.8%). Less comorbidity and invasive surgery and shorter anesthesia were associated with lower mortality and morbidity after renal surgery. Despite volume disparities, the magnitude of difference was only 0.7% in complications and 0.5% in mortality.