Use of male condoms during and after randomized, controlled trial participation in Cameroon.

BACKGROUND AND OBJECTIVE: This study evaluated patterns of long-term use of male condoms among partners of 966 Cameroonian women who received eight intensive, monthly counseling sessions about condoms and sexually transmitted infection testing and treatment. METHOD: An interrupted time-series design was used with study participants reporting condom use and other covariates at enrollment, monthly for 6 months during the randomized, controlled trial, and at approximately 14 months after the trial. RESULTS: Consistent condom use began decreasing while women were still receiving monthly condom use counseling, with every month in the trial associated with an odds ratio of 0.96 (95% confidence interval [CI], 0.94-0.99) of consistent condom use and dropped substantively after the trial with a 0.39 (95% CI, 0.26-0.59) odds ratio in a logistic regression analysis. The incidence of unprotected coital acts as each month passed increased by 3% (95% CI, 1-4%) with no statistically significant change during the condom use follow-up survey as indicated in a zero-inflated Poisson regression model for unprotected coital acts. Condom use in a coital act was 0.84 (95% CI, 0.78-0.92) less likely during the follow-up survey than during the trial. CONCLUSION: Only a few women sustained consistent condom use throughout the study period and for more than 1 year after. It is important to continue documenting the impact of condom promotion in a rigorous manner and to identify content and delivery of counseling that will lead to sustained condom use beyond the intervention period.

Evaluating factors associated with STD infection in a study with interval-censored event times and an unknown proportion of participants not at risk for disease.

Sexually transmitted diseases (STD) are a major cause of morbidity and mortality world-wide. Because of their association with an increased risk of infection with human immunodeficiency virus, the prevention and control of STD are particularly important. Studies designed to evaluate factors associated with the transmission of STD can pose a number of statistical challenges, however. Two such concerns are the interval-censored event times that result from spacing between follow-up test visits, and an unknown proportion of study participants who are not at risk for infection. Researchers in various fields of study have used parametric mixture models to account for individuals not at risk. Owing to non-identifiability concerns within the mixture model framework, however, it is not always possible to distinguish between effects of explanatory variables on the distribution of event times for at-risk individuals and their effects on the probability of being at risk. We address these issues using data from a clinical trial designed to investigate the effectiveness of an intravaginal microbicide in preventing male-to-female transmission of STD. Factors associated with time to infection among at-risk women are initially identified by fitting right-truncated models to the interval-censored event times of participants who tested positive for STD, and hence are known to have been at risk. Subsequently, factors associated with the probability of being at risk are evaluated using mixture models that incorporate information contributed by the right-censored event-free times of uninfected study participants.

Effect of nonoxynol-9 gel on urogenital gonorrhea and chlamydial infection: a randomized controlled trial.

CONTEXT: Nonoxynol-9 has been suggested as a vaginal microbicide to protect against common sexually transmitted infections. OBJECTIVE: To compare nonoxynol-9 gel and condom use (gel group) vs condom use alone (condom group) for the prevention of male-to-female transmission of urogenital gonococcal and chlamydial infection. DESIGN AND SETTING: Randomized controlled trial conducted at 10 community clinics and 10 pharmacies in Yaoundé, Cameroon, between October 1998 and September 2000, with 6 months of follow-up. PARTICIPANTS: High-risk population of 1251 women (excluding sex workers) being treated for or who had symptoms of sexually transmitted infections. Three were excluded from the gel group (0.5%) and 7 from the condom group (1%) because of no follow-up data. INTERVENTIONS: Nonoxynol-9 gel (100 mg) and condoms or condoms only. MAIN OUTCOME MEASURE: A positive test result for gonococcal or chlamydial infection by the ligase chain reaction assay; secondary outcome measure was a positive test result for human immunodeficiency virus (HIV). RESULTS: The rate ratio (RR) for new urogenital infections was 1.2 for the gel group vs condom group (95% confidence interval [CI], 0.9-1.6; P =.21). The gel group had 116 diagnosed gonococcal infections, chlamydial infections, or both for a rate of 43.6 per 100 person-years, and the condom group had 100 infections for a rate of 36.6 per 100 person-years. The RR for gonococcal infection in the gel group vs the condom group was 1.5 (95% CI, 1.0-2.3) and for chlamydial infection was 1.0 (95% CI, 0.7-1.4). There were 5 new cases of HIV infections in the gel group and 4 in the condom group. Three women in each group became pregnant during the study. CONCLUSION: Nonoxynol-9 gel did not protect against urogenital gonococcal or chlamydial infection.