Ecological analysis of the association between high-risk population parameters and HIV prevalence among pregnant women enrolled in sentinel surveillance in four Southern India states

Abstract

Background: The HIV epidemic is very heterogeneous at the district level in the four Southern states of India most affected by the epidemic and where transmission is mainly heterosexual. The authors carried out an ecological study of the relationship between high-risk population parameters and HIV prevalence among pregnant women (ANC HIV prevalence).

Methods: The data used in this study included: ANC HIV prevalence available from the National AIDS Control Organization (dependent variable); data on prevalence of HIV and other sexually transmitted infections among female sex workers (FSWs), their clients and high-risk men who have sex with men (HR-MSM) from studies carried out in 24 districts under Avahan; data on clients' volume reported by FSWs and on the size estimates of FSWs and HR-MSM in each district; and census data. The latter two sets of data were used to estimate the percentage of female (male) adults who are FSWs (HR-MSM). The latter was also multiplied by HIV prevalence in FSWs (HR-MSM) to obtain the percentage of HIV-positive FSWs (HR-MSM) in the adult female (male) population. Linear regression was used for statistical analyses.

Results: In univariate analyses, HIV (r=0.59, p=0.002) and HSV-2 (r=0.49, p=0.014) prevalence among FSWs and mean number of clients in the last week reported by FSWs (r=0.43, p=0.036) were significant predictors of ANC HIV prevalence. In multivariate analysis, only FSW HIV prevalence remained significant.

Conclusions: This ecological study suggests that there is a link between HIV prevalence among FSWs and the spread of HIV to the general population in Southern India. Such an observation supports the rationale of interventions targeted at the sex industry.

Figure 1

Scatter plot and predicted values according to univariate linear regression models relating HIV prevalence in the ANC population (dependent variable) and: (A) HIV prevalence among female sex workers (FSWs) (r=0.5946; R²=0.3535; HIV (ANC)=0.66827+0.04822 HIV (FSW)); (B) herpes simplex type 2 (HSV-2) prevalence among FSWs (r=0.4937; R²=0.2437; HIV (ANC)=−0.29325+0.02626 HSV-2 (FSW)); (C) mean number of clients in the last week reported by FSWs (r=0.4294; R²=0.1844; HIV (ANC)=0.47883+0.10869 (mean number of clients); (D) the proportion of HIV-positive FSWs among the adult female population (r=0.3796; R²=0.1441; HIV (ANC)=1.02945+2.08035 (% HIV+ FSW in female population)), in 24 districts of Andhra Pradesh, Maharashtra, Tamil Nadu and Karnataka.