Objectives: This study assessed whether participant baseline characteristics modified the effects of a skill-based intervention promoting condom use.
Study: The randomized, controlled trial enrolled 427 women from a sexually transmitted disease clinic in Birmingham, Alabama. The main outcome measures: consistent (100%) and problem-free (correct, no breakage or slippage) condom use were verified by sexual diary self-report and contraceptive product counts.
Results: The enhanced intervention group had a 60% higher consistent condom use rate compared to the basic group (risk ratio [RR], 1.6; 95% confidence interval [CI], 1.4–1.8). There was no statistically significant difference between groups in relationship to problem-free, consistent use (RR, 1.0; 95% CI, 0.9–1.1). A binomial regression analysis identified the following factors as significant modifiers of intervention effectiveness on consistent condom use: intention to use condoms next time, early-age sexual debut, marital status combined with place of intercourse, and substance use before sex.
Conclusions: The results suggest that participant baseline characteristics can be modifiers of intervention effectiveness.