Two, three, and four-drug regimens for HIV post-exposure prophylaxis in a North American sexual assault victim population.

Background/objectives: Due to perceived increased tolerability and compliance, and decreased cost, recent trends in practice are moving towards using fewer drugs for HIV post-exposure prophylaxis. However, there is limited literature to assess this is in the North American sexual assault victim population.

Methods: This retrospective before-and-after cohort study compared patients seen at a sexual assault care facility before and after the introduction of two and three-drug post-exposure prophylaxis regimens. Our primary outcome was completion of the 28-day regimen. Secondary objectives included HIV seroconversion rates and patient reported side effects.

Results: Six-hundred-thirty charts from a 2-year period were reviewed, and 429 met inclusion criteria. There was no difference in completion rates of post-exposure prophylaxis between the two cohorts (50.5% vs. 51.6%). However, there were fewer reported side effects (72.2% vs. 17.6%) in the later cohort. We subsequently compared all patients in either cohort who received four-drug therapy (N=128) versus those who received two or three-drug regimens (N=47). The two or three-drug regimen group had a higher completion rate (66.0% vs. 42.2%; p=0.03), and a lower rate of reported side effects (19.1% vs. 53.9%), specifically for nausea (12.8% vs. 36.7%), constipation (0% vs. 7.9%), diarrhea (2.1% vs. 21.1%), mood changes (0% vs. 10.9%), headache (2.1% vs. 16.4%), and fatigue (6.4% vs. 26.6%). There were no HIV seroconversions in either group.

Conclusion: Two and three-drug HIV post-exposure prophylaxis regimens are better tolerated by patients and associated with greater compliance than four-drug therapy, and could be considered in the sexual assault victim population.