title: Do physician practice styles persist over time? Continuities in patterns of clinical decision-making among general practitioners.
abstract: OBJECTIVE
  This study seeks to determine whether there are identifiable differences in patterns of clinical decision-making among family physicians, and whether these patterns persist over time.
  
  
  METHODS
  A representative cross-sectional survey of general practice encounters in the Waikato region of New Zealand in 1979-1980 was repeated in 1991-1992. Patterns of clinical decision-making were operationalised as practitioner rates for writing a prescription, ordering a laboratory test or radiological examination and the recommendation of a future follow-up office visit at a specified date. Comparable data were available for a cohort of 50 physicians in both surveys. Multi-level techniques and a simulation exercise were used to study the patterns of decision-making over time.
  
  
  RESULTS
  Raw, unadjusted correlations for the 50 family physicians between the two surveys were 0.24, 0.14 and 0.55 for rates of prescribing, investigations and follow-up, respectively. However, these correlations increased substantially, to 0.55, 0.41 and 0.70, once account was taken of case mix, data clustering and inter-practitioner variation in patient sample size. The extent of this recovery of the underlying correlations was confirmed in a parallel simulation exercise.
  
  
  CONCLUSIONS
  This study confirms the existence of substantial and durable individual practice styles in primary medical care, with implications for the development and successful implementation of clinical guidelines.
authors.affiliation: Department of Public Health and General Practice, University of Otago, Christchurch, New Zealand.
authors.forename: P
authors.initials: P
authors.lastname: Davis
authors.forename: B
authors.initials: B
authors.lastname: Gribben
authors.forename: A
authors.initials: A
authors.lastname: Scott
authors.forename: R
authors.initials: R
authors.lastname: Lay-Yee
mesh_terms: D003430:Cross-Sectional Studies; D003657:Decision Making; D005194:Family Practice / Q000706:statistics & numerical data*; D019538:Health Care Surveys; D006301:Health Services Needs and Demand; D006801:Humans; D009520:New Zealand; D017410:Practice Guidelines as Topic / Q000592:standards*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D011320:Primary Health Care