The effect of increased risk behaviour among MSM: Results from prospective cohort study confirm results of mathematical model

15 August 2012

On 7 July 2012, an article by Ard van Sighem and Daniela Bezemer of SHM in collaboration with colleagues from the GGD-Amsterdam and Imperial College London was published in AIDS, which compared two estimates of changes in risk behaviour of MSM in the Netherlands.

One of the estimates was based on fitting a mathematical model to the annual number of HIV and AIDS diagnoses in the Netherlands from 1980 to 2009. Independently, estimates of changes in risk behaviour were based on rates of unprotected anal sex measured in a prospective cohort study among MSM in Amsterdam.

Both approaches gave similar results and confirmed that an increased sexual risk behaviour among MSM after the introduction of combination therapy in the mid 1990’s partly negated the beneficial effects of earlier HIV testing and HIV treatment in preventing new infections.

However, risk behaviour does not appear to have increased over the last few years. SHM reported in its Monitoring Report 2011  that the yearly increase in the number of new HIV diagnoses in men who have sex with men (MSM) does not appeared to have continued in 2009 and 2010.


Increasing sexual risk behaviour amongst Dutch MSM: mathematical model versus prospective cohort data. Van Sighem A, Jansen I, Bezemer D, de Wolf F, Prins M, Stolte I, Fraser C; AIDS. 2012 Jul 7. [Epub ahead of print] Abstract