title: Introducing a methodology for estimating duration of surgery in health services research.
abstract: OBJECTIVE
  The duration of surgery is an indicator for the quality, risks, and efficiency of surgical procedures. We introduce a new methodology for assessing the duration of surgery based on anesthesiology billing records, along with reviewing its fundamental logic and limitations.
  
  
  METHODS
  The validity of the methodology was assessed through a population-based cohort of patients (n=480,986) undergoing elective operations in 246 Ontario hospitals with 1,084 anesthesiologists between April 1, 1992 and March 31, 2002 (10 years).
  
  
  RESULTS
  The weaknesses of the methodology relate to missing data, self-serving exaggerations by providers, imprecisions from clinical diversity, upper limits due to accounting regulations, fluctuations from updates over the years, national differences in reimbursement schedules, and the general failings of claims base analyses. The strengths of the methodology are in providing data that match clinical experiences, correspond to chart review, are consistent over time, can detect differences where differences would be anticipated, and might have implications for examining patient outcomes after long surgical times.
  
  
  CONCLUSIONS
  We suggest that an understanding and application of large studies of surgical duration may help scientists explore selected questions concerning postoperative complications.
authors.affiliation: Department of Medicine, Infectious Disease, and Health Policy Management & Evaluation, University of Toronto, Toronto, Ontario, Canada. dar@ices.on.ca
authors.forename: Donald A
authors.initials: DA
authors.lastname: Redelmeier
authors.forename: Deva
authors.initials: D
authors.lastname: Thiruchelvam
authors.forename: Nick
authors.initials: N
authors.lastname: Daneman
mesh_terms: D000776:Anesthesiology / Q000191:economics / Q000592:standards*; D002983:Clinical Competence / Q000191:economics / Q000592:standards; D003362:Cost-Benefit Analysis; D017558:Elective Surgical Procedures / Q000191:economics / Q000592:standards*; D017048:Health Care Costs / Q000592:standards; D006302:Health Services Research / Q000191:economics / Q000592:standards*; D006801:Humans; D016344:Medicare Part A / Q000191:economics / Q000592:standards; D009864:Ontario / Q000453:epidemiology; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology