Studies assessing risk of sexual behavior and disease are often plagued by questions about the reliability of self-reported sexual behavior. In this study, we evaluated the reliability of self-reported sexual history among urbanized women in a prospective study of cervical HPV infections in Nigeria.

We examined test–retest reliability of sexual practices using questionnaires administered at study entry and at follow-up visits. We used the root mean squared approach to calculate within-person coefficient of variation (CV_w) and calculated the intra-class correlation coefficient (ICC) using two way, mixed effects models for continuous variables and statistics for discrete variables. To evaluate the potential predictors of reliability, we used linear regression and log binomial regression models for the continuous and categorical variables, respectively.

We found that self-reported sexual history was generally reliable, with overall ICC ranging from 0.7 to 0.9; however, the reliability varied by nature of sexual behavior evaluated. Frequency reports of non-vaginal sex (agreement = 63.9%, 95% CI: 47.5–77.6%) were more reliable than those of vaginal sex (agreement = 59.1%, 95% CI: 55.2–62.8%). Reports of time-invariant behaviors were also more reliable than frequency reports. The CV_w for age at sexual debut was 10.7 (95% CI: 10.6–10.7) compared with the CV_w for lifetime number of vaginal sex partners, which was 35.2 (95% CI: 35.1–35.3). The test–retest interval was an important predictor of reliability of responses, with longer intervals resulting in increased inconsistency (average change in unreliability for each 1 month increase = 0.04, 95% CI = 0.07–0.38, p = 0.005).

Our findings suggest that overall, the self-reported sexual history among urbanized Nigeran women is reliable.