Rates of New Human Immunodeficiency Virus (HIV) Diagnoses After Reported Sexually Transmitted Infection in Women in Louisiana, 2000-2015: Implications for HIV Prevention.

Background: Human immunodeficiency virus (HIV) prevention interventions for prevention interventions for women include screening, partner notification, promoting condoms, and preexposure prophylaxis (PrEP). Women's risk of acquiring HIV can help guide recommendations.

Methods: We used data from Louisiana's sexually transmitted infection (STI) and HIV registries to study 13- to 59-year-old women following first diagnosis of syphilis, gonorrhea, or chlamydia during 2000-2015. We measured HIV rates reported subsequent to STI (through 2016). Rates for women without STI were estimated by subtracting women with STI from reported cases and from Census estimates for the population. PrEP cost was estimated as $11 000 per year, and effectiveness estimated as 100%.

Results: STIs were syphilis (6574), gonorrhea (64 995), or chlamydia (140 034). These 211 603 women had 1 865 488 person-years of follow-up and 969 HIV diagnoses. Women with no STI had 5186 HIV diagnoses over 24 359 397 person-years. HIV rates diagnosis (per 100 000 person-years) were higher for women after syphilis (177.3), gonorrhea (73.2), or chlamydia (35.4) compared to women with no STI (22.4). Providing PrEP to all women diagnosed with syphilis or gonorrhea would cost $7 371 111 000 and could have prevented 546 HIV diagnoses. Limiting PrEP to 1 year after syphilis or gonorrhea diagnosis would cost $963 847 334, but only 143 HIV diagnoses were within 2 years after a syphilis or gonorrhea diagnosis.

Conclusions: Rates of HIV diagnosis were high after women had STI, but not high enough to make PrEP cost-effective for them. Most women diagnosed with HIV did not have previously reported STI.