Predictors of Unprotected Sex Among Female Sex Workers in Madagascar: Comparing Semen Biomarkers and Self-Reported Data

Abstract

Research on the determinants of condom use and condom non-use generally has relied on self-reported data with questionable validity. We identified predictors of recent, unprotected sex among 331 female sex workers in Madagascar using two outcome measures: self-reports of unprotected sex within the past 48 h and detection of prostate-specific antigen (PSA), a biological marker of recent semen exposure. Multivariable logistic regression revealed that self-reported unprotected sex was associated with three factors: younger age, having a sipa (emotional partner) in the prior seven days, and no current use of hormonal contraception. The sole factor related to having PSA detected was prevalent chlamydial infection (adjusted odds ratio, 4.5; 95% confidence interval, 2.0–10.1). Differences in predictors identified suggest that determinants of unprotected sex, based on self-reported behaviors, might not correlate well with risk of semen exposure. Caution must be taken when interpreting self-reported sexual behavior measures or when adjusting for them in analyses evaluating interventions for the prevention of HIV/STIs.

Prostate-specific antigen as a biomarker of condom failure: comparison of three laboratory assays and self-reported condom use problems in a randomized trial of female condom performance

“…Previously conducted studies [2][3][4]7,[12][13][14][15][16] have typically employed only a single PSA assay. Our findings indicated a remarkable consistency of biomarker results regarding the presence or absence of semen exposure across the three PSA assays.…”

“…Recent studies that have compared PSA measurement with self-reported condom use and use problems suggest that PSA provides a more complete measure of condom failure during vaginal intercourse [13][14][15][16]. Methods for measuring PSA, however, vary in characteristics, performance and cost, and their comparability with respect to assessing condom performance has not been adequately evaluated.…”

Exploring Discordance Between Biologic and Self-Reported Measures of Semen Exposure: A Qualitative Study Among Female Patients Attending an STI Clinic in Jamaica

“…By virtue of its validity and immediacy, PSA rapid testing can be utilized in other studies of sexual behavior, in conjunction with other quantitative and qualitative methods, to gain additional information about study participants' experiences in real-time. The utilization of PSA and other semen biomarkers help illuminate bias in self-reported data, and can also serve as primary study outcomes [5,22,32]. As this trend continues, it represents a breakthrough for sexual health research.…”

“…However, studies also show that PSA degrades rapidly in the vagina, returning to baseline levels in 24-48 h after exposure [18]. Studies comparing PSA test results with self-reported sexual behaviors have identified high levels of discordance between the two, confirming concerns about the under-reporting of unprotected sexual activity and over-reporting of condom use [7,[19][20][21][22][23].…”

Sexual Relationship Power and Semen Exposure Among Female Patients at a Sexually Transmitted Infection Clinic in Kingston, Jamaica

“…These studies may have identified correlates of the reporting of behavior, rather than the behavior itself (Gallo, et al, 2010). For example, social desirability bias could have resulted in women both over-reporting their relationship power as well as their actual use of condoms and, in this way, overestimated the scale's ability to predict condom use.…”