Distinct HIV discordancy patterns by epidemic size in stable sexual partnerships in sub-Saharan Africa

Abstract

Objective: To describe patterns of HIV infection among stable sexual partnerships across sub-Saharan Africa (SSA).

Methods: The authors defined measures of HIV discordancy and conducted a comprehensive quantitative assessment of discordancy among stable partnerships in 20 countries in SSA through an analysis of the Demographic and Health Survey data.

Results: HIV prevalence explained at least 50% of the variation in HIV discordancy, with two distinct patterns of discordancy emerging based on HIV prevalence being roughly smaller or larger than 10%. In low-prevalence countries, approximately 75% of partnerships affected by HIV are discordant, while only about half of these are discordant in high-prevalence countries. Out of each 10 HIV infected persons, two to five are engaged in discordant partnerships in low-prevalence countries compared with one to three in high-prevalence countries. Among every 100 partnerships in the population, one to nine are affected by HIV and zero to six are discordant in low-prevalence countries compared with 16-45 and 9-17, respectively, in high-prevalence countries. Finally, zero to four of every 100 sexually active adults are engaged in a discordant partnership in low-prevalence countries compared with six to eight in high-prevalence countries.

Conclusions: In high-prevalence countries, a large fraction of stable partnerships were affected by HIV and half were discordant, whereas in low-prevalence countries, fewer stable partnerships were affected by HIV but a higher proportion of them were discordant. The findings provide a global view of HIV infection among stable partnerships in SSA but imply complex considerations for rolling out prevention interventions targeting discordant partnerships.

Figure 1

Measures of discordancy among stable sexual partnerships across 20 countries in sub-Saharan Africa. (A) Schematic diagram describing the presence of HIV discordancy among stable sexual partnerships in the sexually active population. (B) The proportion of HIV discordant partnerships among all stable partnerships with at least one HIV-infected individual in the partnership ($P_{\mathit{discord}}$), and the proportion of all HIV-infected individuals engaged in stable HIV discordant partnerships ($l_{\mathit{pos}}$). (C) The proportion of stable discordant partnerships among all stable partnerships $\left(P_{\mathit{all}}\right)$. (D) The proportion of individuals engaged in stable HIV discordant partnerships $\left(l_{\mathit{all}}\right)$. Countries are shown in order of increasing HIV prevalence.

Figure 2

Variability in measures of discordancy with respect to HIV prevalence across 20 countries in sub-Saharan Africa. Variation with respect to HIV prevalence of the proportion of HIV discordant partnerships among all stable partnerships with at least one HIV-infected individual in the partnership ($P_{\mathit{discord}}$) and of the proportion of HIV-infected individuals that are engaged in stable HIV discordant partnerships among the sexually active population ($l_{\mathit{pos}}$).