title: Does the early adopter of drugs exist? A population-based study of general practitioners' prescribing of new drugs.
abstract: OBJECTIVE
  To analyse associations between indicators for adoption of new drugs and to test the hypothesis that physicians' early adoption of new drugs is a personal trait independent of drug groups.
  
  
  METHODS
  In a population-based cohort study using register data, we analysed the prescribing of new drugs by Danish general practitioners. Angiotensin-II antagonists, triptans, selective cyclo-oxygenase-2 antagonists and esomeprazol were used in the assessment. As indicators of new drug uptake, we used adoption time, cumulative incidence, preference proportion, incidence rate and prescription cost and volume. For each measure, we ranked the general practices. Ranks were pair-wise plotted, and Pearson's correlation coefficient ( r) was calculated. Next, we analysed the correlation between ranks across different drug classes.
  
  
  RESULTS
  For all indicators, the general practitioners' adoption of one group of drugs was poorly associated with adoption of others ( r</=0.49), indicating that early adoption of one type of drugs is not associated with early adoption of another. For all drug groups, adoption time adjusted for practice size was only weakly associated with other indicators ( r: -0.56 to -0.27). Indicators, based on cost and volume of drugs, were highly correlated ( r: 0.96-0.99), and the others correlated reasonably well ( r: 0.51-0.91).
  
  
  CONCLUSIONS
  Within drug groups, indicators of drug adoption, except for adoption time, correlate reasonably well. However, the theory that physicians' early adoption of new drugs is a personal trait independent of the type of drug could not be confirmed. The notion of the early-drug-adopting general practitioner may be mistaken.
authors.affiliation: Research Unit of General Practice, Institute of Public Health, University of Southern Denmark, Winsløwparken 19, 3rd, 5000, Odense C, Denmark. tdybdahl@health.sdu.dk
authors.forename: Torben
authors.initials: T
authors.lastname: Dybdahl
authors.forename: Morten
authors.initials: M
authors.lastname: Andersen
authors.forename: Jens
authors.initials: J
authors.lastname: Søndergaard
authors.forename: Jakob
authors.initials: J
authors.lastname: Kragstrup
authors.forename: Ivar Sønbø
authors.initials: IS
authors.lastname: Kristiansen
mesh_terms: D015331:Cohort Studies; D016208:Databases, Factual / Q000706:statistics & numerical data*; D003657:Decision Making; D003718:Denmark; D004358:Drug Therapy; D004363:Drug Utilization / Q000191:economics / Q000706:statistics & numerical data; D005194:Family Practice / Q000706:statistics & numerical data*; D006801:Humans; D010821:Physicians, Family / Q000706:statistics & numerical data*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D013997:Time Factors