title: Can administrative data be used to compare postoperative complication rates across hospitals?
abstract: BACKGROUND
  Several quality assessment systems use administrative data to identify postoperative complications, with uncertain validity.
  
  
  OBJECTIVE
  To determine how accurately postoperative complications are reported in administrative data, whether accuracy varies systematically across hospitals, and whether serious complications are more consistently reported.
  
  
  METHODS
  Retrospective cohort.
  
  
  METHODS
  Nine hundred ninety-one randomly sampled adults who underwent elective lumbar diskectomies at 30 nonfederal acute care hospitals in California in 1990 to 1991. Hospitals with especially low or high risk-adjusted complication rates, and patients who experienced complications, were over sampled.
  
  
  METHODS
  Postoperative complications were specified by reviewing medical literature and consulting clinical experts; each complication was mapped to ICD-9-CM. Hospital-reported complications were compared with our independent recoding of the same records.
  
  
  RESULTS
  The weighted sensitivity, specificity, and positive and negative predictive values for reported complications were 35%, 98%, 82%, and 84%, respectively. The weighted sensitivity was 30% for serious, 40% for minor, and 10% for questionable complications. It varied from 21% among hospitals with fewer complications than expected to 45% among hospitals with more complications than expected. Only reoperation, bacteremia/sepsis, postoperative infection, and deep vein thrombosis were reported with at least 60% sensitivity. Half of the difference in risk-adjusted complication rates between low and high outlier hospitals was attributable to reporting variation.
  
  
  CONCLUSIONS
  ICD-9-CM complications were underreported among diskectomy patients, especially at hospitals with low risk-adjusted complication rates. The validity of using coded complications to compare provider performance is questionable, even with careful efforts to identify serious events, although these results must be confirmed using more recent data.
authors.affiliation: Division of General Medicine, Department of Internal Medicine, and the Center for Health Services Research in Primary Care, University of California Davis School of Medicine, Sacramento 95817, USA. psromano@ucdavis.edu
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Romano
authors.forename: Benjamin K
authors.initials: BK
authors.lastname: Chan
authors.forename: Michael E
authors.initials: ME
authors.lastname: Schembri
authors.forename: Julie A
authors.initials: JA
authors.lastname: Rainwater
mesh_terms: D002140:California / Q000453:epidemiology; D017586:Diskectomy / Q000009:adverse effects*; D004812:Epidemiologic Methods; D005568:Forms and Records Control; D006302:Health Services Research / Q000379:methods* / Q000592:standards; D006761:Hospitals / Q000592:standards*; D006801:Humans; D038801:International Classification of Diseases; D008499:Medical Records / Q000592:standards*; D017063:Outcome Assessment, Health Care / Q000379:methods* / Q000592:standards; D011183:Postoperative Complications / Q000145:classification* / Q000453:epidemiology; D011785:Quality Assurance, Health Care / Q000379:methods / Q000592:standards; D019984:Quality Indicators, Health Care; D015203:Reproducibility of Results