LAUSR

A population-based, Southern statewide observational cohort study found that syphilis was associated with the highest risk of incident human immunodeficiency virus diagnosis overall as compared with chlamydia, regardless of self-reported sexual practices. Background Data on associations between sexually transmitted infections (STIs) and incident human immunodeficiency virus (HIV) diagnoses beyond men who have sex with men (MSM) are lacking. Identifying STIs associated with greatest risk of incident HIV diagnosis could help better target HIV testing and prevention interventions. Methods The STI and HIV surveillance data from individuals 13 years or older in Tennessee from January 2013 to December 2017 were cross-matched. Individuals without diagnosed HIV, but with reportable STIs (chlamydia, gonorrhea, syphilis) were followed up from first STI diagnosis until HIV diagnosis or end of study. Cox regression with time-varying STI exposure was used to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (CI) for subsequent HIV diagnosis; results were stratified by self-reported MSM. Results We included 148,465 individuals without HIV (3831 MSM; 144,634 non-MSM, including heterosexual men and women) diagnosed with reportable STIs; 473 had incident HIV diagnoses over 377,823 person-years (p-y) of follow-up (median, 2.6 p-y). Controlling for demographic and behavioral factors, diagnoses of gonorrhea, early syphilis, late syphilis, and STI coinfection were independently associated with incident HIV diagnosis compared with chlamydia. Early syphilis was associated with highest HIV diagnosis risk overall (aHR, 5.5; 95% CI, 3.5–5.8); this risk was higher for non-MSM (aHR, 12.3; 95% CI, 6.8–22.3) versus MSM (aHR, 2.9; 95% CI, 1.7–4.7). Conclusions While public health efforts often focus on MSM, non-MSM with STIs is also a subgroup at high risk of incident HIV diagnosis. Non-MSM and MSM with any STI, particularly syphilis, should be prioritized for HIV testing and prevention interventions.