Background Postexposure prophylaxis (PEP) is a recommended public health intervention after a sexual assault to prevent HIV infection.

Methods We conducted a retrospective case-control study on how use of a single-tablet regimen (STR) of elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate (Stribild) affected adherence to PEP and attendance of a follow-up visit to the STI clinic compared with those who received a multitablet regimen (MTR). Data from sexual assault victims consulting for PEP were prospectively recorded between January 2011 and December 2017. Data were systematically collected on patient demographics, time of medical contact, source risk factors, type of exposure, attendance to follow-up visit, reported completion of PEP and adherence based on pharmacy records.

Results A total of 422 patients received PEP following a sexual assault, of whom 52% had documented completion of a 28-day PEP regimen and 71% attended a follow-up clinic visit. Patients who received an elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate (EVG/COBI/FTC/TDF)-based STR had a similar likelihood of attending their first follow-up visit (OR: 0.97; 95% CI: 0.64 to 1.48, p=0.90) but were more likely to complete the PEP regimen (OR: 1.70; 95% CI: 1.16 to 2.50, p=0.007). After adjusting for confounders, those who were prescribed an STR regimen were more likely to complete the PEP regimen (OR: 1.66, 95% CI: 1.09 to 2.53, p=0.019) than those who were prescribed an MTR such as stavudine/lamivudine/lopinavir/ritonavir or zidovudine/lamivudine/indinavir/ritonavir.

Conclusions Sexual assault victims who were prescribed an STR based on EVG/COBI/FTC/TDF were more likely to complete PEP than those who were prescribed an MTR.