title: Standard definitions of adherence for infrequent yet repeated health behaviors.
abstract: OBJECTIVE
  To present common language for defining adherence of infrequent yet repeated health behaviors.
  
  
  METHODS
  We illustrate methodological and conceptual issues using human papillomavirus (HPV) vaccination and screening mammography study data as examples.
  
  
  RESULTS
  Adherence rates of infrequent, repeated behaviors varied widely depending on how adherence was defined and measured. We advocate use of 3 standard definitions of adherence: initiation of behavior (initiation), adherence to most recent opportunity (on-schedule), and timely adherence across multiple opportunities (maintenance or completion).
  
  
  CONCLUSIONS
  The proposed framework has cross-cutting implications for research and practice. Standardizing adherence metrics may facilitate comparisons across studies of health behaviors practiced at infrequent yet repeated intervals.
authors.affiliation: Duke University-Division of General Internal Medicine, Durham VAMC-Center for Health Services Research in Primary Care, Durham, NC 27701, USA. j.gierisch@duke.edu
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Gierisch
authors.forename: Paul L
authors.initials: PL
authors.lastname: Reiter
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Rimer
authors.forename: Noel T
authors.initials: NT
authors.lastname: Brewer
mesh_terms: D005260:Female; D015438:Health Behavior; D006801:Humans; D008327:Mammography / Q000523:psychology; D017063:Outcome Assessment, Health Care / Q000592:standards*; D010349:Patient Compliance / Q000523:psychology / Q000706:statistics & numerical data*; D014611:Vaccination / Q000523:psychology