Participant characteristics associated with withdrawal from a large randomized trial of spermicide effectiveness.
BACKGROUND
In most recent large efficacy trials of barrier contraceptive methods, a high proportion of participants withdrew before the intended end of follow-up. The objective of this analysis was to explore characteristics of participants who failed to complete seven months of planned participation in a trial of spermicide efficacy.


METHODS
Trial participants were expected to use the assigned spermicide for contraception for 7 months or until pregnancy occurred. In bivariable and multivariable analyses, we assessed the associations between failure to complete the trial and 17 pre-specified baseline characteristics. In addition, among women who participated for at least 6 weeks, we evaluated the relationships between failure to complete, various features of their first 6 weeks of experience with the spermicide, and characteristics of the study centers and population.


RESULTS
Of the 1514 participants in this analysis, 635 (42%) failed to complete the study for reasons other than pregnancy. Women were significantly less likely to complete if they were younger or unmarried, had intercourse at least 8 times per month, or were enrolled at a university center or at a center that enrolled fewer than 4 participants per month. Noncompliance with study procedures in the first 6 weeks was also associated with subsequent early withdrawal, but dissatisfaction with the spermicide was not. However, many participants without these risk factors withdrew early.


CONCLUSIONS
Failure to complete is a major problem in barrier method trials that seriously compromises the interpretation of results. Targeting retention efforts at women at high risk for early withdrawal is not likely to address the problem sufficiently.
Family Health International, Research Triangle Park, NC, USA. eraymond@fhi.org
Elizabeth G
EG
Raymond
Pai Lien
PL
Chen
Bosny
B
Pierre-Louis
Joanne
J
Luoto
Kurt T
KT
Barnhart
Lynn
L
Bradley
Mitchell D
MD
Creinin
Alfred
A
Poindexter
Livia
L
Wan
Mark
M
Martens
Robert
R
Schenken
Cate F
CF
Nicholas
Richard
R
Blackwell
D000328:Adult; D003075:Coitus; D003268:Contraception Behavior; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D009042:Motivation; D017137:Nonoxynol / Q000008:administration & dosage* / Q000494:pharmacology; D011247:Pregnancy; D011258:Pregnancy Tests; D045808:Refusal to Participate / Q000523:psychology / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012107:Research Design; D035842:Research Subjects / Q000145:classification* / Q000523:psychology; D012306:Risk; D013089:Spermatocidal Agents / Q000008:administration & dosage* / Q000494:pharmacology; D013333:Student Health Services; D014481:United States
D013089:Spermatocidal Agents; D017137:Nonoxynol