title: Impact of hospital volume on postoperative complications and in-hospital mortality after renal surgery: data from the Japanese Diagnosis Procedure Combination Database.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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%).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Health Management and Policy, Graduate School of Medicine, University of Tokyo, Japan. yasunagah-jyo@h.u-tokyo.ac.jp
authors.forename: Hideo
authors.initials: H
authors.lastname: Yasunaga
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Yanaihara
authors.forename: Kozo
authors.initials: K
authors.lastname: Fuji
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Horiguchi
authors.forename: Hideki
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Shinya
authors.initials: S
authors.lastname: Matsuda
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016208:Databases, Factual; D005260:Female; D006276:Health Facility Size / Q000706:statistics & numerical data*; D017052:Hospital Mortality; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy / Q000009:adverse effects* / Q000401:mortality*; D011183:Postoperative Complications / Q000453:epidemiology