title: Attrition and non-compliance in secondary stroke prevention trials.
abstract: BACKGROUND
  Attrition and non-compliance of subjects in secondary stroke prevention trials due to study drug-induced adverse events and loss to follow-up could lead to bias and loss of information, thus affecting the analysis of study results.
  
  
  METHODS
  We reviewed results from ten antiplatelet stroke prevention clinical trials: CAN TIA, DUTCH TIA, SWED ASA, SALT, UK TIA, CATS, TASS, ESPS, ESPS-2, and CAPRIE to tabulate the frequencies for total subject discontinuation, voluntary withdrawal, and loss to follow-up.
  
  
  RESULTS
  Forty thousand seven hundred and thirty (40,730) subjects participated in the aforementioned secondary stroke prevention trials. The range of outcomes was 11.8-52.0% for subjects discontinued for any reason (n = 9 trials); 3.0-20.9% for study drug-induced adverse events (n = 9 trials), and 4.2-7.8% for voluntary withdrawal (n = 10 trials).
  
  
  CONCLUSIONS
  There is a substantial discrepancy (up to 20%) between the frequencies of total subject discontinuation for any reason and the sum of study drug-induced adverse events, voluntary withdrawal and loss to follow-up. Underestimation of these important outcomes may limit the ability of clinicians to translate results from clinical trials into medical practice.
authors.affiliation: Department of Neurological Sciences, Rush Medical College, Chicago, IL, USA. gencheva@hotmail.com
authors.forename: E
authors.initials: E
authors.lastname: Gencheva
authors.forename: M
authors.initials: M
authors.lastname: Sloan
authors.forename: S
authors.initials: S
authors.lastname: Leurgans
authors.forename: R
authors.initials: R
authors.lastname: Raman
authors.forename: Y
authors.initials: Y
authors.lastname: Harris
authors.forename: P
authors.initials: P
authors.lastname: Gorelick
mesh_terms: D000368:Aged; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010352:Patient Dropouts; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects*; D012107:Research Design; D015983:Selection Bias; D020521:Stroke / Q000209:etiology* / Q000517:prevention & control*; D016312:Treatment Refusal
chemical_list: D010975:Platelet Aggregation Inhibitors