Mathematical Insights in Evaluating State Dependent Effectiveness of HIV Prevention Interventions
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Mathematical models have been used to simulate HIV transmission and to study the use of preexposure prophylaxis (PrEP) for HIV prevention. Often a single intervention outcome over 10 years has been used to evaluate the effectiveness of PrEP interventions. However, different metrics express a wide variation over time and often disagree in their forecast on the success of the intervention. We develop a deterministic mathematical model of HIV transmission and use it to evaluate the public-health impact of oral PrEP interventions. We study PrEP effectiveness with respect to different evaluation methods and analyze its dynamics over time. We compare four traditional indicators, based on cumulative number or fractions of infections prevented, on reduction in HIV prevalence or incidence and propose two additional methods, which estimate the burden of the epidemic to the public-health system. We investigate the short and long term behavior of these indicators and the effects of key parameters on the expected benefits from PrEP use. Our findings suggest that public-health officials considering adopting PrEP in HIV prevention programs can make better informed decisions by employing a set of complementing quantitative metrics.
KeywordsHIV transmission HIV prevalence or incidence PrEP interventions ODE model
D.D. is supported by a grant from the National Institutes of Health (Grant number 5 U01 AI068615-03). Y.Z., H.L., and Y.K. are supported in part by DMS-0920744.
The authors thank the anonymous referees for many useful comments on an earlier draft.
- AIDS epidemic update: November 2009. UNAIDS/WHO, 2009. http://data.unaids.org/pub/report/2009/jc1700_epi_update_2009_en.pdf.
- Alsallaq, R. A., Schiffer, J. T., Longini, I. M., Wald, A., Corey, L., & Abu-Raddad, L. J. (2010). Population level impact of an imperfect prophylactic vaccine for Herpes Simplex Virus-2. Sex. Transm. Dis., 37, 290–297. Google Scholar
- Desai, K., Sansom, S. L., Ackers, M. L., Stewart, S. R., Hall, H. I., Hu, D. J., Sanders, R., Scotton, C. R., Soorapanth, S., Boily, M. C., Garnett, G. P., & McElroy, P. D. (2008). Modeling the impact of HIV chemoprophylaxis among men who have sex with men in the United States: infections prevented and cost-effectiveness. AIDS, 22, 1829–1839. CrossRefGoogle Scholar
- Hallett, T. B., Alsallaq, R. A., Baeten, J. M., Weiss, H., Celum, C., Gray, R., & Abu-Raddad, L. (2011). Will circumcision provide even more protection from HIV to women and men? New estimates of the population impact of circumcision interventions. Sex. Transm. Infect., 87, 88–93. CrossRefGoogle Scholar
- Karim, Q. A., Karim, S. S. A., Frohlich, J. A., Grobler, A. C., Baxter, C., Mansoor, L. E., Kharsany, A. B. M., Sibeko, S., Mlisana, K. P., Omar, Z., Gengiah, T. N., Maarschalk, S., Arulappan, N., Mlotshwa, M., Morris, L., Taylor, D., & and on behalf of the CAPRISA 004 Trial Group (2010). Effectiveness and safety of tenofovir gel, an antiretroviral microbicide, for the prevention of HIV infection in women. Science, 329, 1168–1174. CrossRefGoogle Scholar
- Mid-year population estimates 2011. Statistics South Africa http://www.statssa.gov.za/publications/P0302/P03022011.pdf
- Partners PrEP Study Team (2011). Pivotal study finds that HIV medications are highly effective as prophylaxis against HIV infection in men and women in Africa. Press Release 2011. http://depts.washington.edu/uwicrc/research/studies/files/PrEP_PressRelease-UW_13Jul2011.pdf
- Wawer, M. J., Gray, R. H., Sewankambo, N. K., Serwadda, D., Li, X. B., Laeyendecker, O., Kiwanuka, N., Kigozi, G., Kiddugavu, M., Lutalo, T., Nalugoda, F., Wabwire-Mangen, F., Meehan, M. P., & Quinn, T. C. (2005). Rates of HIV-1 transmission per coital act, by stage of HIV-1 infection, in Rakai, Uganda. J. Infect. Dis., 191, 1403–1409. CrossRefGoogle Scholar
- World Health Organization (WHO) (2003). Making choices in health: WHO guide to cost effectiveness analysis. Geneva: World Health Organization. http://whqlibdoc.who.int/publications/2003/9241546018.pdf. Google Scholar