Self-reported behavior has been the cornerstone of sexual health research and clinical practice, yet advances in sexually transmitted disease (STD) screening provide researchers with the opportunity to objectively quantify sexual risk behaviors. However, the extent to which young adults' laboratory-confirmed STD results and self-reported sexual behaviors are consistent has not been assessed in a nationally representative sample.
Data are derived from participants who completed wave 3 in the National Longitudinal Study of Adolescent Health. Young adults (N = 14 012) completed an audio computer-assisted self-interviewing survey and provided a urine specimen to detect the presence of Chlamydia trachomatis and Neisseria gonorrhoeae, and a polymerase chain reaction assay to detect Trichomonas vaginalis.
More than 10% of young adults with a laboratory-confirmed positive STD result reported abstaining from sexual intercourse in the 12 months before assessment and STD testing. After controlling for several sociodemographic factors, self-reported sex (versus those who reported abstinence) in the previous 12 months was significantly associated with testing positive, but the odds of testing positive were only slightly more than twofold (adjusted odds ratio: 2.11 [95% confidence interval: 2.097–2.122]).
Findings indicate discrepancy between young adults' positive STD status and self-reported sexual behavior. No significant correlates of discrepant reporting were identified. From a clinical standpoint, the discrepancies between STD positivity and self-reported sexual behavior observed in this nationally representative sample suggest that routine STD screening may be beneficial and necessary to reduce STD morbidity among young adults.
A recent analysis by DiClemente and colleagues of data from a nationally-representative sample of young adults in the US found discordance between reports of sexual behavior and sexually transmitted infection (STI) status.1 Specifically, >10% of those with a positive nucleic acid amplification test for nonviral STIs reported no sex in the prior 12 months. About 6% of those who tested positive reported never having had penile-vaginal sex. Note that these figures do not provide the overall rate of under-reporting of recent sex. Only individuals with an infected partner are at risk of infection and, thus, could have discordant self-reports and STI test results. Given the discrepancy in self-reporting of sexual activity, the authors conclude that clinicians should test all young people for prevalent STIs rather than screen based on sexual history.
These clinical findings further corroborate recent research evaluating the validity of self-reported sexual behavior among adult women based on the identification of a biological marker of semen exposure in vaginal fluid, most notably, prostate-specific antigen (PSA) or spermatozoa Y-chromosome sequences.2 PSA, a protein found in high concentrations in seminal plasma, is detectable in vaginal fluid for up to 48 hours following exposure to semen.3-6 Thus, the detection of PSA in vaginal swabs provides an objective measure of a woman’s recent exposure to semen. Unlike STIs, PSA can be used to identify a greater proportion of acts of unprotected sex (i.e., not just acts occurring with an infected partner in which the infection was transmitted). That said, because PSA begins to clear from the vagina almost immediately post-exposure and generally clears completely within 48 hours, the proportion testing positive for PSA should be interpreted as the lower bound of the proportion who were exposed to semen in past 48 hours.
Substantial proportions of female sex workers in Guinea (36%),7 Kenya (11%)8 and Madagascar (29%)9 who reported no unprotected sex in the past 48 hours tested positive for PSA. The detection of PSA also revealed substantial, apparent under-reporting of recent unprotected sex among low- risk women in Zimbabwe.10 Finally, an analysis comparing data from two studies conducted among women in Alabama and Brazil found similar rates of PSA detection in the two populations but different rates of problems reported with condom use.11 This finding suggests that reports of condom problems also might not be valid.
While none of these outcomes (PSA detection, STI diagnoses or self- reports of unprotected sex) are likely to capture all cases of recent exposure to semen, PSA detection could be expected to be a less biased measure. That is, the ability to detect PSA among those with recent semen exposure is unlikely to be differential with respect to factors such as participant characteristics or behaviors. In contrast, only participants who have an infected partner could have a STI diagnosis, and among participants who had recent semen exposure, those who elect to report engaging in unprotected sex might be very different than those who do not report this behavior. For example, evaluations of condom promotion interventions or abstinence-only curricula often rely on self-reported outcomes. However, the intervention itself could affect the reporting of the outcome; social desirability bias could cause participants receiving the intervention to under-report engaging in unprotected sex to a greater degree than participants in the control arm, which could lead to erroneous conclusions regarding the intervention’s effectiveness.
Self-reported data on sexual behavior have long been a cornerstone of HIV/STI research and are widely employed. In another recent report on the validity of self-reports of condom use, Lipovsek et al. wrote: “The general consensus is that the reliability and validity of self-reporting is questionable; but there is also agreement that it is, by and large, the only feasible way to measure sexual behaviors.”12 The report by DiClemente and colleagues adds to a body of evidence demonstrating that other methods do exist for improving measurement of sexual behavior where self reports considered alone might not be sufficiently valid.
Maria F. Gallo,* Markus J. Steiner,** Lee Warner,* Marcia M. Hobbs,† Denise J. Jamieson,* Maurizio Macaluso‡
*Division of Reproductive Health, Centers for Disease Control and Prevention **Clinical Sciences Division, FHI †Departments of Medicine and Microbiology & Immunology, University of North Carolina ‡ Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center The findings and conclusions in this letter are those of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention.
References
1. Diclemente RJ, Sales JM, Danner F, et al. Association between sexually transmitted diseases and young adults' self-reported abstinence. Pediatrics. 2011 Jan 3 [Epub ahead of print]
2. Mauck CK, Doncel GF, Biomarkers of Semen Exposure Clinical Working Group. Biomarkers of semen in the vagina: applications in clinical trials of contraception and prevention of sexually transmitted pathogens including HIV. Contraception. 2007;75(6):407–419
3. Graves HC, Sensabaugh GF, Blake ET. Postcoital detection of a male -specific semen protein. Application to the investigation of rape. N Engl J Med. 1985;312(6):338–343
4. Kamenev L, Leclercq M, Francois-Gerard C. An enzyme immunoassay for prostate-specific p30 antigen detection in the postcoital vaginal tract. J Forensic Sci Soc. 1989;29(4):233–241
5. Lawson ML, Maculuso M, Bloom A, et al. Objective markers of condom failure. Sex Transm Dis. 1998;25(8):427–432
6. Macaluso M, Lawson L, Akers R, et al. Prostate-specific antigen in vaginal fluid as a biologic marker of condom failure. Contraception. 1999;59(3):195–201
7. Aho J, Koushik A, Diakité SL, et al. Biological validation of self -reported condom use among sex workers in Guinea. AIDS Behav. 2010;14(6):1287–1293
8. Gallo MF, Behets FM, Steiner MJ, et al. Validity of self-reported ‘safe sex’ among female sex workers in Mombasa, Kenya—PSA analysis. Int J STD AIDS. 2007;18(1):33–38
9. Gallo MF, Behets FM, Steiner MJ, et al. Prostate-specific antigen to ascertain reliability of self-reported coital exposure to semen. Sex Transm Dis. 2006;33(8):476–479
10. Minnis AM, Steiner MJ, Gallo MF, et al. Biomarker validation of reports of recent sexual activity: results of a randomized controlled study in Zimbabwe. Am J Epidemiol. 2009;170(7):918–924
11. Chen, MP, Macaluso M, Blackwell R, et al. Self-reported mechanical problems during condom use and semen exposure. Comparison of two randomized trials in the United States of America and Brazil. Sex Transm Dis. 2007;34(8):557–562
12. Lipovsek V, Longfield K, Buszin J. Can follow-up study questions about correct and consistent condom use reduce respondent over-reporting among groups at high risk? An analysis of datasets from six countries. Reprod Health. 2010:7(9)
Conflict of Interest:
None declared
I am not familiar with the questionnaire used in the study, however, in the event, it focused on the term "sexually active", that may be a reason for some of the unreliable responses. In our high school clinic we stopped asking students if they are sexually active. Instead we also ask female students how many times they have had sex in a given period of time, e.g. a week. Like your study results, we discovered what seemed like a blatant lie during an exam. Female student’s labs clearly indicated sexual activity yet female students would state they were not active. When we followed up the question with another question, such as, how many times you had sex in the past week, the student responded with a specific number of times. When we asked them to clarify the discrepancy, the female student always stated they were telling the truth, they were not "active" partners in the sexual act. From their perspective, the question was not asking if they were abstinent but rather if they “actively” participate in the physical encounter.
Conflict of Interest:
None declared