title: Relationship between hospital volume and operative mortality for liver resection: Data from the Japanese Diagnosis Procedure Combination database.
abstract: OBJECTIVE
  The present study aimed to conduct a nationwide investigation on the relationship between hospital volume and outcomes following liver resection in Japan. We also discuss health policy implications of the results.
  
  
  METHODS
  Using the Japanese Diagnosis Procedure Combination database, we identified 18 046 patients who underwent hepatic resection between July and December 2007-2009. Patients were subdivided into hospital-volume quartiles: very low- (<18/year), low- (18-35), high- (36-70) and very high-volume groups (>70). Multivariate logistic regression analysis for in-hospital mortality within 30 days of surgery was performed to analyze adjusted effects of various factors.
  
  
  RESULTS
  Patients in the very high-volume group had a higher Charlson Comorbidity Index (P < 0.001) than those in the very low-volume group. Very low-volume hospitals were significantly less likely to perform extended lobectomy than very high-volume hospitals (5.4% vs 17.6%, P < 0.001). Crude in-hospital mortality within 30 days of surgery was 1.1% (0.6%, 0.8%, 1.9% and 3.0% for limited resection, segmentectomy, lobectomy and extended lobectomy, respectively). With reference to the very low-volume group, risk-adjusted odds ratios (95% confidence intervals) of low-, high- and very high-volume groups for overall mortality were 0.70 (0.48-1.02; P = 0.060), 0.52 (0.34-0.81; P = 0.004) and 0.16 (0.09-0.30; P < 0.001), respectively.
  
  
  CONCLUSIONS
  There is a linear trend between higher hospital volume and lower in-hospital mortality of liver resection in Japan, particularly for lobectomy and extended lobectomy. Based on these results, regionalization of lobectomy and extended lobectomy in high-volume centers could be effective for reducing postoperative mortality.
authors.affiliation: Departments of Health Management and Policy             Medical Informatics and Economics             Department of Surgery, Hepato-Biliary-Pancreatic Surgery Division, Artificial Organ and Transplantation Division, Graduate School of Medicine             Department of Health Economics and Epidemiology Research, School of Public Health, The University of Tokyo             Department of Health Policy and Informatics, Tokyo Medical and Dental University Graduate School of Medicine, Tokyo             Department of Preventive Medicine and Community Health, University of Occupational and Environmental Health, Fukuoka, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Yasunaga
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Horiguchi
authors.forename: Shinya
authors.initials: S
authors.lastname: Matsuda
authors.forename: Kiyohide
authors.initials: K
authors.lastname: Fushimi
authors.forename: Hideki
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ohe
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kokudo