Assessment of population-level effect of Avahan, an HIV-prevention initiative in India
Published October 10, 2011, in The Lancet (opens in a new window)
Avahan, a program aimed at preventing HIV in India, averted an estimated 100,178 HIV infections between 2003 and 2008, according to researchers at IHME, the Public Health Foundation of India, the Ministry of Health and Family Welfare of India, and the University of Hong Kong. This research, published in the study “Assessment of population-level effect of Avahan, an HIV-prevention initiative in India,” showed that HIV prevention programs that target high-risk groups can reduce HIV in the general population.
India has one of the world’s largest populations infected with HIV – an estimated 2.4 million people in 2009. Avahan was launched in 2003 with $258 in funding from the Bill & Melinda Gates Foundation and aims to slow the transmission of HIV in the general population by increasing prevention interventions in high-risk groups, including sex workers and their clients, men who have sex with men, and injecting drug users.
The states targeted by Avahan were the ones with the highest HIV rates in 2003: four large states in south India (Andhra Pradesh, Karnataka, Maharashtra, and Tamil Nadu) and two small states in the northeast (Manipur and Nagaland). Avahan interventions included peer outreach for safe-sex counseling, treatment for sexually transmitted infections, distribution of free condoms, needle and syringe exchanges, and community advocacy activities.
Understanding the effect of large-scale HIV prevention programs like Avahan is critical, as research on the effect of such initiatives is sparse, due largely to the lack of available evidence to undertake rigorous assessment of these programs. The researchers assessed the population-level effect of the first phase of Avahan (from 2003 to 2008) to determine how well the program worked at preventing HIV.
Overall, the researchers estimated that 100,178 HIV infections were prevented at the population level between 2003 and 2008 as a result of Avahan, with 61% in men. The reduction in HIV prevalence in the general population due to Avahan varied between states, ranging from 2.4% in Maharashtra to 12.7% in Karnataka. Greater intensity of Avahan, which was measured as the amount of grants per population with HIV, was significantly associated with lower HIV prevalence in Andhra Pradesh, Karnataka, and Maharashtra.
The researchers note that because of the uncertainty associated with the variables in the model and the underlying data, the findings should be interpreted with caution.
Under ideal conditions, a prospective evaluation of the impact of Avahan in the general population would have been initiated simultaneously with the program, allowing for comparison between interventions and control districts with people not receiving the Avahan interventions. Because this evaluation was not built into the program, the researchers devised a way to estimate the effect of Avahan on the general public through an observational study.
The researchers note that there are four challenges to such an assessment: reliable estimates of population-level HIV prevalence are lacking; surveillance for HIV began in 1992 in urban locations in the six high-prevalence states and now they have expanded to include most districts in the country, meaning that estimates from earlier years are biased because they are from areas with higher HIV prevalence; the HIV epidemic is heterogeneous, and states differ in terms of HIV prevalence and stages of epidemics; and the difficulty in identifying the change in HIV trends due to the natural course of the disease versus that of the intervention.
The authors addressed these challenges by estimating population HIV prevalence using adjustment factors with the national HIV sentinel surveillance data obtained annually from antenatal clinics in India. To estimate the association between the intensity of the Avahan intervention and trends in HIV prevalence in the population, the researchers developed a mixed-effects multilevel regression model that took into account differences in the underlying epidemic trends and other potential confounders, including education level and whether a person resides in an urban or rural setting.
The results of this analysis suggest there is a strong association between the large-scale Avahan prevention program in India and reductions in HIV prevalence at the population level. Further detailed studies of Avahan, currently in progress, are necessary to understand the pathways by which Avahan is effective and which intervention methods work best. The authors also note the need for large-scale health intervention programs, such as Avahan, to have data gathering built into the study design to allow for prospective assessments of the effect of the intervention at the population level.
Although funding for HIV treatment has increased over the past five years, funding for HIV prevention has stagnated. While it has been suggested that antiretroviral treatment reduces HIV transmission, inadequate HIV prevention will lead to an increase in need for antiretroviral treatment, which will not be sustainable over the long term. The findings of this study support strategic investment in well planned and managed HIV prevention programs, in India as well as globally.
Bill & Melinda Gates Foundation – Disease Control Priorities Network (Investment # OPP51229)
Ng M, Gakidou E, Levin-Rector A, Khera A, Murray CJL, Dandona L. Assessment of population-level effect of Avahan, an HIV-prevention initiative in India. The Lancet. 2011; DOI:10.1016/S0140-6736(11)61390-1.