HIV Prophylaxis with PrEP: Less May be More

Pre-exposure prophylaxis (PrEP) saves lives by reducing the risk of acquiring HIV, but drug costs average $6,000 to $17,000 a year, per person. With recent declines in government funding, the need for cost-saving is great.

A study published in the journal AIDS indicates that prioritizing high-risk populations and using intermittent instead of daily prophylaxis can reduce PrEP costs. This systematic review examined factors influencing the costs of non-daily oral PrEP with tenofivir +/- emtricitabine, focusing on men who have sex with men (MSM) and heterosexual populations.

Pharmacists may be unfamiliar with non-daily dosing, mainly because they are investigational and researchers have proposed numerous structures including:

• Time-driven dosing (1 tablet twice per week plus 1 tablet after sexual intercourse)
• Event-driven dosing (1 tablet before and 1 tablet after sex)
• An alternative, 2 tablets before sex, and 2 tablets 24 hours later

This study aimed to determine populations and patterns of sexual behavior in which non-daily oral prep would reduce overall costs, compared to daily regimens. The researchers determined a number of tablets required for non-daily oral PrEP regimens, sexual activity patterns, PrEP program costs, and potential cost-savings for non-daily oral PrEP.

To estimate potential costs, they considered dosing requirements, frequency of sex in priority populations, and oral PrEP drug and program costs. The median number of sex-days per week varied between 0 and 1.5 for the MSM population and 1 to 2 for heterosexual populations. Using the median number of 1 sex-day/week, program cost reduction for non-daily regimens fell by 66% to 69%.

Intermediate dosing can reduce drug costs by at least 50% in high-income countries. In countries where drug cost was lower and sexual activity higher, cost reduction was more modest.

Studies have proven that non-daily oral PrEP can be effective in preventing HIV infections. The authors expressed concern over adherence in non-daily regimens, which may be more difficult for patients than daily treatments. This and the imperfect prediction of future sexual activity may decrease effectiveness of non-daily regimens. A more comprehensive cost-effectiveness analysis will be necessary to evaluate full benefits.

Blerina Mukallari is a 2018 PharmD Candidate at the University of Connecticut.

Reference

Mitchell KM, Dimitrov D, Hughes JP, et al. In what circumstances could nondaily preexposure prophylaxis for HIV substantially reduce program costs? AIDS. 2018:1. doi:10.1097/qad.0000000000001766.