Background
Publicly-funded oral HIV PrEP has been available to key populations in British Columbia (BC) through the BC Centre for Excellence in HIV/AIDS since 2018. We examined differences in characteristics of PrEP enrollees with and without subsequent HIV diagnoses.
Methods
We included clients with ≥1 PrEP prescription dispensed between 1-Jan-2018 and 31-Dec-2023 (follow-up to 30-Jun-2024). Baseline demographic, clinical, and PrEP prescription characteristics were reported (totals, and by HIV status at end of follow-up) using descriptive statistics. Wilcoxon rank sum and Fisher’s exact tests were used to compare variables between groups.
Results
Overall, 12,389 clients were included, with median (Q1-Q3) age 32 (27-41) years, 95.8% were cis-men, 1.7% trans-women, 0.9% cis-women, 0.6% trans-men, and 0.5% non-binary. 12,152 (98.1%) identified as gay, bisexual or other men who have sex with men (MSM), and median HIV incidence risk index (HIRI-MSM) score was 18 (14-22). Clients had a median (Q1-Q3) of 6 (3-12) PrEP prescriptions over a median follow-up of 31 (15-58) months. Over the study period, 12,316 clients (99.4%) remained HIV negative and 73 (0.6%) were subsequently diagnosed with HIV at median (Q1-Q3) 32 (13-50) months after enrollment, median 10 (5-19) months after their previous negative HIV test, and median 13 (6-28) months after anticipated PrEP medication run out (based on dispensing records and once-daily dosing). Only 5 clients appeared to have PrEP medication supply at the time of diagnosis. Median (Q1-Q3) age was 31 (25-37) years; 71 were cis-men. Median (Q1-Q3) time to ART initiation after diagnosis was 7 (4-17) days. There were differences in age, proportion with HIRI-MSM score ≥25, known substance use and incident syphilis between clients with and without HIV diagnoses. Long terminal lapses in PrEP medication (max 67 months) and HIV testing (max 61 months) were also observed among seroconverters (Table). The new HIV diagnosis rate in the overall cohort was 0.19 per 100 PY (95% CI: 0.15-0.23) over 37,434 PY of follow-up. The rate was 0.12 per 100 PY (95% CI: 0.08-0.15) when follow-up was censored after 18 months.
Conclusions
Few new HIV diagnoses occurred in enrollees engaged with PrEP medication. Incident syphilis, and lapses in HIV testing and PrEP dispensing may serve to alert providers to re-engage with clients. Strategies to support long-term engagement in PrEP care are needed, in particular for younger persons, those with high HIRI-MSM score, and known substance use.