Mathematical models for the study of HIV spread and control amongst men who have sex with men

Abstract

For a quarter of century, mathematical models have been used to study the spread and control of HIV amongst men who have sex with men (MSM). We searched MEDLINE and EMBASE databases up to the end of 2010 and reviewed this literature to summarise the methodologies used, key model developments, and the recommended strategies for HIV control amongst MSM. Of 742 studies identified, 127 studies met the inclusion criteria. Most studies employed deterministic modelling methods (80%). Over time we saw an increase in model complexity regarding antiretroviral therapy (ART), and a corresponding decrease in complexity regarding sexual behaviours. Formal estimation of model parameters was carried out in only a small proportion of the studies (22%) while model validation was considered by an even smaller proportion (17%), somewhat reducing confidence in the findings from the studies. Nonetheless, a number of common conclusions emerged, including (1) identification of the importance of assumptions regarding changes in infectivity and sexual contact rates on the impact of ART on HIV incidence, that subsequently led to empirical studies to gather these data, and (2) recommendation that multiple strategies would be required for effective HIV control amongst MSM. The role of mathematical models in studying epidemics is clear, and the lack of formal inference and validation highlights the need for further developments in this area. Improved methodologies for parameter estimation and systematic sensitivity analysis will help generate predictions that more fully express uncertainty, allowing better informed decision making in public health.

Modelling the HIV epidemic among MSM in the United Kingdom

“…Our sensitivity analysis (Appendix, section 6, http:// links.lww.com/QAD/A612) also confirmed that non-PHI infectiousness was one of the most important drivers of the epidemic, while PHI-related parameters were not among them. There were also a number of recent studies that arrived at similar findings [26][27][28][29]. A recent systematic review by Blaser et al [25] suggested that HIV transmission rate during PHI should be around 10 and 30 times higher than that of asymptomatic stage if PHI lasted, respectively, for 6 and 2 months.…”

Effect of pre-exposure prophylaxis and combination HIV prevention for men who have sex with men in the UK: a mathematical modelling study

“…Our analysis confi rmed the importance of implementation of a combination of interventions for eff ective HIV control in MSM. 13,17 The provision of PrEP as part of a combination strategy, even to a quarter of highly sexually active individuals, could prevent more than 7000 new HIV infections in the UK before the end of this decade. The relatively small coverage the programme requires is feasible because around half of Data are median (IQR), unless otherwise indicated.…”

“…Findings from our previous study 3 suggested that undiagnosed HIV, repeat sexual partnerships, and young and high-activity MSM were the most important drivers of the HIV epidemic in UK MSM. Several interventions have been proposed in modelling studies 13 and have garnered interest. 14,15 We consequently formed and investigated seven individual HIV interventions: (1.1) test for HIV once a year; (1.2) test for HIV twice a year; (1.3) a test-and-treat programme assuming the ART initiation rate of those with CD4 count of less than 350 cells per μL to all diagnosed MSM regardless of CD4 count; (1.4) PrEP; (1.5) reducing the number of repeat sexual partners by 0•5 times; (1.6) reducing the number of one-off sexual partners by 0•5 times; and (1.7) reducing unprotected anal intercourse with repeat sexual partners by 0•5 times.…”

Impact of High-Risk Sex and Focused Interventions in Heterosexual HIV Epidemics: A Systematic Review of Mathematical Models

“…Previous modeling reviews have been mostly narrative [44], [45]. We have tried to make our review as quantitative as possible, as well as assess study quality.…”