Statistical Analysis

An STI was defined as chlamydia, gonorrhea, or trichomoniasis by NAAT testing. The study was powered for HSV-2 acquisition. Based on HSV-2 prevalence data (8), projected incidence of 7.8% per year, and a median age of sexual debut of 18 (9), we assumed that enrolling 400 HSV-2 seronegative persons would result in 73 observed HSV-2 acquisitions, accounting for 13% dropout.

Data were entered into a password-secured REDCap database (10). Descriptive statistics were used to characterize the cohort. We examined whether STI positivity was associated with education, socioeconomic status, sexual history, and physical exam findings. χ² test and Fisher's exact test were used to compare categorical variables, and t-test for independent samples for continuous variables. A multivariate logistic regression model was constructed, adjusting for possible cofactors of STI (age, BV, sexual activity, education level, rural residence, vaginal discharge). Each cofactor was added stepwise to the model and included in the final model if significantly associated (p <0.1). Data were analyzed using Stata version 15.1 (StataCorp, College Station, Texas); statistical significance was defined as 2-sided p value <0.05. Missing data was left out of the analysis.