JMIR Publications

ABSTRACT

Background:

Estimating the size of key populations (KP) including female sex workers (FSW) and men who have sex with men (MSM) can inform HIV programs at local and national levels. In places where population size estimates (PSE) for KP are unavailable, small area estimation (SAE) can help fill in gaps using auxiliary data. However, routine program data have not historically been included as auxiliary data in KP SAE approaches.

Objective:

To systematically generate regional size estimates for FSW and MSM in Namibia, we used a consensus-informed approach with local stakeholders in addition to routinely collected HIV program data provided by KP partners.

Methods:

Quarterly program data reported by KP implementing partners were used to re-weight existing PSEs collected through bio-behavioral surveys using a consensus estimation approach. Extrapolated estimates were generated through simple imputation, stratified imputation, and multivariable Poisson regression. Final estimates were validated using an iterative qualitative ranking process with KP partners.

Results:

Extrapolated national estimates for FSW ranged from 4,777 to 13,148 across Namibia, comprising 1.5% to 3.6% of women ages 15-49. For MSM, estimates ranged from 4,611 to 10,171, comprising 0.7%-1.5% of men ages 15-49. The inclusion of program data increased the proportion of FSW in high-density regions and decreased the proportion of MSM in all regions.

Conclusions:

Using SAE approaches, we combined epidemiologic and program data to generate subnational size estimates for KP in Namibia. Program data represent a supplemental source of information that can be used to align PSEs with real-world HIV programs, particularly in regions where population-based data collected methods are challenging to implement. Future work is needed to determine how best to include program data in target setting and in KP size estimation studies, ultimately bridging research with practice to support a more comprehensive HIV response.