title: Perioperative patient safety indicators and hospital surgical volumes.
abstract: BACKGROUND
  Since the late 1990s, patient safety has been an important policy issue in developed countries. To evaluate the effectiveness of the activities of patient safety, it is necessary to quantitatively assess the incidence of adverse events by types of failure mode using tangible data. The purpose of this study is to calculate patient safety indicators (PSIs) using the Japanese Diagnosis Procedure Combination/per-diem payment system (DPC/PDPS) reimbursement data and to elucidate the relationship between perioperative PSIs and hospital surgical volume.
  
  
  METHODS
  DPC/PDPS data of the Medi-Target project managed by the All Japan Hospital Association were used. An observational study was conducted where PSIs were calculated using an algorithm proposed by the US Agency for Healthcare Research and Quality. We analyzed data of 1,383,872 patients from 188 hospitals who were discharged from January 2008 to December 2010.
  
  
  RESULTS
  Among 20 provider level PSIs, four PSIs (three perioperative PSIs and decubitus ulcer) and mortality rates of postoperative patients were related to surgical volume. Low-volume hospitals (less than 33rd percentiles surgical volume per month) had higher mortality rates (5.7%, 95% confidence interval (CI), 3.9% to 7.4%) than mid- (2.9%, 95% CI, 2.6% to 3.3%) or high-volume hospitals (2.7%, 95% CI, 2.5% to 2.9%). Low-volume hospitals had more deaths among surgical inpatients with serious treatable complications (38.5%, 95% CI, 33.7% to 43.2%) than high-volume hospitals (21.4%, 95% CI, 19.0% to 23.9%). Also Low-volume hospitals had lower proportion of difficult surgeries (54.9%, 95% CI, 50.1% to 59.8%) compared with high-volume hospitals (63.4%, 95% CI, 62.3% to 64.6%). In low-volume hospitals, limited experience may have led to insufficient care for postoperative complications.
  
  
  CONCLUSIONS
  We demonstrated that PSIs can be calculated using DPC/PDPS data and perioperative PSIs were related to hospital surgical volume. Further investigations focusing on identifying risk factors for poor PSIs and effective support to these hospitals are needed.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Kitazawa
authors.forename: Kunichika
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Shigeru
authors.initials: S
authors.lastname: Fujita
authors.forename: Ai
authors.initials: A
authors.lastname: Yoshida
authors.forename: Shuhei
authors.initials: S
authors.lastname: Iida
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Nishizawa
authors.affiliation: Department of Social Medicine, Toho University School of Medicine, 5-21-16, Omori-nishi, Ota-ku, Tokyo 143-8540, Japan. tommie@med.toho-u.ac.jp.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Hasegawa
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D061214:Patient Safety / Q000592:standards / Q000706:statistics & numerical data*; D059035:Perioperative Period; D011787:Quality of Health Care / Q000592:standards / Q000706:statistics & numerical data; D018570:Risk Assessment / Q000379:methods / Q000706:statistics & numerical data; D012307:Risk Factors; D017751:Safety Management / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data*; D013503:Surgery Department, Hospital / Q000706:statistics & numerical data*