Prostate-specific antigen (PSA) is a valid biomarker of semen exposure in women and has been used to assess reliability of self-reported sexual behavior as well as serve as a proxy measure for condom efficacy. Quantitative PSA tests are expensive and require specialized equipment. A simple, rapid, and inexpensive test for PSA would facilitate semen biomarker evaluation in a variety of research settings. This study evaluated the performance of a rapid PSA test compared with a quantitative assay to identify semen in vaginal swab specimens.
We tested 581 vaginal swabs collected from 492 women participating in 2 separate research studies in Bangladesh and Zimbabwe. PSA in vaginal secretions was detected using the quantitative IMx (Abbott Laboratories) assay and the ABAcard p30 (Abacus Diagnostics) rapid immunochromatographic strip test.
The ABAcard test was 100% sensitive (95% confidence interval [CI], 98%–100%) and 96% specific (95% CI, 93%–97%) compared with the quantitative test in detecting >1.0 ng PSA/mL vaginal swab eluate. Rapid PSA results were semiquantitative and correlated well with PSA concentrations (κ = 0.88; 95% CI, 0.85–0.90).
Rapid PSA detection requires no instrumentation and can be performed easily and economically. Having rapid PSA results available immediately following interview provides opportunities to explore discrepancies between the objective marker of recent semen exposure and self-reported behaviors.
Performance of a rapid, immunochromatographic strip test for detection of prostate-specific antigen was similar to quantitative prostate-specific antigen test results for detection of semen in vaginal swabs.
From the *Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; †Family Health International, Research Triangle Park, North Carolina; ‡Centers for Disease Control and Prevention, Atlanta, Georgia; §International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh; and ∥Department of Obstetrics and Gynecology, University of Zimbabwe, Harare, Zimbabwe.
Supported in part by the US National Institutes of Health through the North Carolina Sexually Transmitted Infections and Topical Microbicides Cooperative Research Center grant U19-AI031496 and a developmental award from the UNC Center for AIDS Research grant P30-AI050410 (to M.M.H.); and Centers for Disease Control and Prevention (CDC) and the Contraceptive and Reproductive Health Technologies Research and Utilization (CRTU) program of the United States Agency for International Development (USAID) with funds from cooperative agreement #GPO-A-OO-05-00022-00 (to M.J.S.). IMx test kits were generously donated by Abbott Laboratories.
The authors thank Robert Krysiak and Dana Lapple for technical assistance; Irving Hoffman, Duncan McCormack, and William Miller for support of the Bangladesh study; and Alexandra Minnis and Nancy Padian for support of the Zimbabwe study.
The findings and conclusions in this report are those of the authors and do not necessarily represent the official positions of the funding agencies.
Correspondence: Marcia M. Hobbs, PhD, Department of Medicine, CB# 7031, UNC School of Medicine, Chapel Hill, NC 27599. E-mail: firstname.lastname@example.org.
Received for publication November 4, 2008; and accepted February 17, 2009.