O1-S10.01 High HIV incidence among MSM who were prescribed HIV-PEP: indications for further riskful sexual behaviour
Authors: Heuker J , Sonder G , Stolte I , van den Hoek A 
Published: July 2011

Background

Are MSM who were prescribed PEP, men with high risk behaviour or men who incidentally had a riskful sexual contact? One way to answer this question is to compare the HIV incidence among MSM who were prescribed PEP with the HIV incidence among MSM without such request, using HIV incidence as a surrogate marker for highly riskful sexual behaviour.

Methods

The HIV-PEP cohort consisted of MSM who were prescribed a 28 day PEP-course after a riskful sexual contact between 2000 and 2009 in Amsterdam, the Netherlands, who were HIV negative at baseline and had a follow-up HIV test at 3 and 6 months. Predictors for seroconversion were analysed using χ2tests and Mann–Whitney U tests. The comparison cohort consisted of MSM participating in the Amsterdam Cohort Studies (ACS) who were tested every 6 months in the same study period. The latter cohort aims to represent the overall gay community in Amsterdam. HIV incidences, including 95% CIs, were calculated for both cohorts by dividing newly diagnosed HIV-infections by total Person Years (PY) under observation.

Results

The HIV-PEP cohort comprised of 395 PEP prescriptions (n=321 MSM with one PEP prescription; n=34 MSM with two or more PEP prescriptions) with a total follow up time of 169.45 PY. The median age at PEP prescription was 35 (IQR 30-41) and 62 % was born in the Netherlands. In 61% of the cases PEP was prescribed for receptive unprotected anal intercourse (RUAI) and MSM who seroconverted were more likely to report RUAI compared to those who did not seroconvert (82% and 60% resp.; p=0.15). In the ACS cohort 809 MSM participated with a total follow-up time of 4412 PY. The median age at visit in the ACS was 32 (IQR 28-36) and 86% was born in the Netherlands. The HIV incidence in the time period 2005–2009, as well as the overall HIV incidence in the total study period, was four times higher in the HIV-PEP cohort compared to the ACS (Abstract O1-S10.01 table 1). In the HIV-PEP cohort the overall HIV incidence was 6.49 (95% CI 3.24% to 11.62%) per 100 PY, compared to 1.59 (95 % CI 1.25% to 2.0% per 100 PY in the MSM in the ACS in the same study period (p<0.001).

Abstract O1-S10.01 Table 1

HIV incidences among MSM of the HIV-PEP cohort and of the Amsterdam Cohort Studies (ACS), 2000–2009

HIV-PEP cohortACSTime periodNo. of serocon-versionsPerson Years (PY) under observationIncidence density per 100 PY (95% CI)No. of serocon-versionsPerson Years (PY) under observationIncidence density per 100 PY (95% CI)p Value2000–2004142.12.38 (0.12 to 11.73)2620951.24 (0.83 to 1.79)NS2005–200910127.47.85 (4.0 to 14.0)4423171.90 (1.40 to 2.53)<0.001Total study period 2000–200911169.56.49 (3.4 to 11.3)7044121.59 (1.25 to 2.0)<0.001

NS: Not Significant.

Conclusions

The HIV incidence of MSM who were prescribed a PEP course was four times higher than in the overall gay community in Amsterdam. Our results show that PEP users belong to a group of MSM at high risk for HIV infection. Further analyses will be conducted to compare predictors of HIV seroconversion in both cohorts.