title: Participants and refusers in a telephone interview about hormone replacement therapy were equally likely to be taking it.
abstract: OBJECTIVE
  To address a major concern in pharmacoepidemiology studies related to whether the characteristics of responders are different from those who refuse to participate.
  
  
  METHODS
  We compared utilization of postmenopausal hormone replacement therapy (HRT) in women who agreed to participate in a telephone interview on HRT utilization and in women who refused to participate in the telephone interview. Information on HRT utilization among responders and refusers was independently available to us from a claims database (the Healthcare Management Alternatives, HMA, in Philadelphia), showing drugs dispensed to these patients.
  
  
  RESULTS
  Out of a random sample of 213 women selected from the claims database whom we contacted, 154 (72.3%) women agreed to participate and 59 (32.7%) women refused. Among the 154 women who agreed to participate, 79 (51.3%, 95% CI: 43.1-59.4%) were shown by the database to have been dispensed an HRT during the 15-month period January 1995 through March 1996. Among the 59 women who refused to participate, 30 (50.8%, 95% CI: 37.5-64.1%) were shown by the database to have been dispensed an HRT during the same period.
  
  
  CONCLUSIONS
  Thus, we have evidence that use of HRT was almost identical in responders and nonresponders.
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, 824 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104-6021, USA. bstrom@cceb.med.upenn.edu
authors.forename: Brian L
authors.initials: BL
authors.lastname: Strom
authors.forename: Rita
authors.initials: R
authors.lastname: Schinnar
mesh_terms: D015914:Estrogen Replacement Therapy / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008875:Middle Aged; D010358:Patient Participation; D017698:Postmenopause; D015983:Selection Bias