Objective: To examine the concordance between teens' and young adults' self-reported condom use, assessed by audio-computer-assisted self-interviewing, and Y-chromosome polymerase chain reaction (Yc-PCR) assay, a nondisease marker for detecting the presence of sperm in vaginal fluid for 14 days after unprotected vaginal sex.
Design: Randomized trial of a human immunodeficiency virus prevention program. Only data from baseline (before randomization) were used for this analysis.
Setting: A clinic-based sample in Atlanta, Georgia.
Participants: Eligible teens and young adults were African American female teens and young adults 15 to 21 years old who had reported sexual activity in the previous 60 days. Of 1558 teens and young adults screened from March 1, 2002, through August 31, 2004, 847 were eligible and 715 (84.4%) participated at baseline.
Main outcome measures: Self-reported consistent condom use in the 14 days before baseline and Yc-PCR results.
Results: Of participants who reported vaginal sex in the past 14 days, 186 reported consistent condom use, defined as 100% condom use. Of these, 63 had a positive Yc-PCR result, indicating detection of the Y chromosome in the vaginal fluid. Participants who reported consistent condom use with a self-reported history of sexually transmitted diseases were 2.4 times more likely to have a positive Yc-PCR result (adjusted odds ratio, 2.4; 95% confidence interval, 1.2-4.8; P = .01).
Conclusions: A significant degree of discordance between self-reports of consistent condom use and Yc-PCR positivity was observed. Several rival explanations for the observed discordance exist, including (1) teens and young adults inaccurately reported condom use; (2) teens and young adults used condoms consistently but used them incorrectly, resulting in user error; and (3) teens and young adults responded with socially desirable answers. Using an objective biological measure may provide one strategy for validating teens' and young adults' self-reported condom use.