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HIV incidence among men who have sex with men prescribed postexposure prophylaxis

Heuker, Joséa; Sonder, Gerarda,b; Stolte, Inekea; Geskus, Ronalda,c; van den Hoek, Annekea,b

doi: 10.1097/QAD.0b013e3283553795

aDepartment of Infectious Disease, Public Health Services

bCenter of Infection and Immunology Amsterdam (CINIMA), Academic Medical Center (University of Amserdam)

cDepartment of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Center (University of Amsterdam), Amsterdam, the Netherlands.

Correspondence to Gerard Sonder, MD, PhD, Public Health Service Amsterdam, Amsterdam, Netherlands. Tel: +31 20 555 5003; fax: +31 20 555 5533; e-mail:

Received 18 April, 2012

Accepted 25 April, 2012

In their correspondence, Puro et al. [1] argue that the difference in incidence we found between the two cohorts in our study could have been confounded by the different ‘time at risk’. The fact that the average follow-up time per individual largely differs in both groups is, however, not problematic, as long as the hazard does not depend on follow-up time. We do not think that, in the Amsterdam Cohort Studies (ACS), selection bias due to ‘ low-risk individuals’ remaining in follow-up after ‘high-risk individuals’ seroconvert is a major problem; the ACS is an open ongoing cohort study, aiming to represent a cohort of MSM living in the Amsterdam region. Also note that the HIV incidence in the ACS did not decrease over calendar time, which would be expected if the incidence in the population is constant, but only low-risk individuals remain in the study. The HIV incidence in the ACS showed a slight, nonsignificant increase from 1.1 per 100 person-years in 2000, to 2.3 per 100 person-years in 2009. This number is lower than the 3.0 per 100 person-years from the non-postexposure prophylaxis (PEP) users in Italy, who probably represent higher risk MSM as they visit a counselling and testing site. Interestingly, both the Italian and our study indicate that risk behaviour is ongoing after PEP prescription, and HIV-incidence in both studies showed an (nonsignificant) increase.

So our main conclusion that MSM requesting PEP in Amsterdam obviously belong to a high-risk group and additional prevention efforts are needed remains unchanged. We do agree with the authors that PEP is not necessarily the only appropriate indication for pre-exposure prophylaxis.

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Conflicts of interest

There are no conflicts of interest.

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1. Puro V, De Carli G, Piselli P, Sciarrone MR, Schifano E, Pittalis S, Ippolito G. HIV incidence among men who have sex with men prescribed postexposure prophylaxis. AIDS 2012; 26:1581–1583.
© 2012 Lippincott Williams & Wilkins, Inc.