title: International comparability of patient safety indicators in 15 OECD member countries: a methodological approach of adjustment by secondary diagnoses.
abstract: OBJECTIVE
  To improve the international comparability of patient safety indicators based on administrative hospital data, adjustment of country-specific rates by a proxy measure of diagnostic coding intensity was tested.
  
  
  METHODS
  Secondary data (numerator and denominator counts of patient safety indicators) based on adults discharged from acute care hospitals between 2006 and 2008 was used.
  
  
  METHODS
  A retrospective cross-sectional study using hospital administrative data was performed.
  
  
  METHODS
  Belgium, Canada, Denmark, Germany, Italy, Ireland, New Zealand, Norway, Portugal, Singapore, Spain, Sweden, Switzerland, the United Kingdom, and the United States provided data according to detailed instructions.
  
  
  RESULTS
  Age- and sex-standardized rates varied across countries. An ordinary least squares regression model was estimated for each Patient Safety Indicator (PSI) using the mean number of secondary diagnoses among denominator cases as the predictor (R(2) =23 percent to 56 percent). Estimated country-specific residuals were linearly transformed into adjusted PSI rates. Variation among age-sex standardized PSI rates decreased substantially after this adjustment.
  
  
  CONCLUSIONS
  International comparisons of health system performance based on unadjusted patient safety indicators are problematic due to suspected coding or ascertainment bias. The model could be an interim approach to provide comparable information on hospital quality, with a long-term goal of improving international consistency in diagnostic reporting in administrative data.
authors.affiliation: Competence Center for Routine Data in Healthcare, Niederrhein University of Applied Sciences, Reinarzstraße 49, D-47805 Krefeld, Germany. saskia.droesler@hs-niederrhein.de
authors.forename: Saskia E
authors.initials: SE
authors.lastname: Drösler
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Romano
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Tancredi
authors.forename: Niek S
authors.initials: NS
authors.lastname: Klazinga
mesh_terms: D000367:Age Factors; D003430:Cross-Sectional Studies; D019049:Developed Countries / Q000706:statistics & numerical data; D006801:Humans; D016018:Least-Squares Analysis; D015233:Models, Statistical; D061214:Patient Safety / Q000592:standards* / Q000706:statistics & numerical data; D019984:Quality Indicators, Health Care / Q000592:standards* / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012737:Sex Factors