Attrition and non-compliance in secondary stroke prevention trials.
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.
Gencheva
E
E
Department of Neurological Sciences, Rush Medical College, Chicago, IL, USA. gencheva@hotmail.com
Sloan
M
M
Leurgans
S
S
Raman
R
R
Harris
Y
Y
Gorelick
P
P
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
D010975:Platelet Aggregation Inhibitors