What antiretroviral regimen has a 28-day completion rate greater than 90% for HIV (Human Immunodeficiency Virus) Post-Exposure Prophylaxis (PEP)?

Bictegravir/Emtricitabine/Tenofovir Alafenamide (Answer B)

Bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) is the only regimen among the options listed that consistently achieves 28-day completion rates greater than 90% for HIV post-exposure prophylaxis. 1

Evidence Supporting BIC/FTC/TAF

The most recent CDC guidelines (2025) provide the strongest evidence for this recommendation:

• Two prospective trials demonstrated completion rates of 90% and 96% with BIC/FTC/TAF, with zero HIV seroconversions in both studies 1
• BIC/FTC/TAF significantly outperformed all other regimens when directly compared to historical controls, including the regimens listed in this question 1
• Additional prospective studies from China confirmed these findings, with completion rates of 96.4% and 97.8% 2, 3

Comparison to Other Options

Option A: Elvitegravir/cobicistat/emtricitabine/TDF

• Completion rates ranged from 44% to 92%, falling short of the 90% threshold in most studies 1
• One specific study showed 71% completion, which was better than older regimens but still below 90% 4

Option C: Emtricitabine/TDF and Raltegravir

• Completion rate was only 57% in the key comparative study 1
• While one study suggested RAL/TDF/FTC could achieve up to 96% completion, this was not consistently replicated and the evidence is mixed 1

Option D: Emtricitabine/rilpivirine/tenofovir alafenamide

• Completion rate was 86.1% in the primary study evaluating this regimen 5
• This falls below the 90% threshold specified in the question 5

Clinical Advantages of BIC/FTC/TAF

Beyond completion rates, BIC/FTC/TAF offers additional benefits:

• Single-tablet, once-daily dosing improves adherence compared to multi-tablet regimens 6, 7
• Lower incidence of side effects compared to other integrase inhibitor-based regimens 1, 7
• Fewer drug-drug interactions than cobicistat-containing regimens 6
• Preferred renal and bone safety profile with TAF versus TDF 8, 9

Common Pitfalls to Avoid

• Do not assume all single-tablet regimens have equivalent completion rates - the evidence clearly shows BIC/FTC/TAF outperforms elvitegravir-based combinations 1
• Do not confuse adherence rates with completion rates - some regimens report high adherence among those who continue but have lower overall completion 1
• Do not delay PEP initiation while deciding between regimens - start with BIC/FTC/TAF immediately if available 6, 8, 9