Untangling the relationship between antiretroviral therapy use and incident pregnancy: A marginal structural model analysis using data from 47,313 HIV-positive women in East Africa
Scale-up of triple-drug antiretroviral therapy (ART) in Africa has transformed the context of childbearing for HIV-positive women, and may impact pregnancy incidence in HIV programs.
Using observational data from 47,313 HIV-positive women enrolled at 26 HIV clinics in Kenya and Uganda between 2001-2009, we calculated the crude cumulative incidence of pregnancy for the pre-ART and on-ART periods. The causal effect of ART use on incident pregnancy was assessed using inverse probability weighted marginal structural models, and the relationship was further explored in multivariable Cox models.
Crude cumulative pregnancy incidence at one year after enrollment / ART initiation was 4.0% and 3.9% during the pre-ART and on-ART periods, respectively. In marginal structural models, ART use was not significantly associated with incident pregnancy (HR=1.06; 95% CI: 0.99-1.12). Similarly, in Cox models, there was no significant relationship between ART use and incident pregnancy (cause-specific HR [CSHR]: 0.98; 95% CI: 0.91-1.05), but effect modification was observed. Specifically, women who were pregnant at enrollment and on ART had an increased risk of incident pregnancy compared to those not pregnant at enrollment and not on ART (CSHR: 1.11; 95% CI: 1.01-1.23).
In this large cohort, ART initiation was not associated with incident pregnancy in the general population of women enrolling in HIV care but rather only among those pregnant at enrollment. This finding further highlights the importance of scaling up access to lifelong treatment for pregnant women.This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND), which permits downloading and sharing the work provided it is properly cited. The work cannot be changed in any way or used commercially.
Elul B, Wools-Kaloustian KK, Wu Y, Musick BS, Nuwagaba-Biribonwoha H, Nash D, Ayaya S, Bukusi E, Okong P, Otieno J, et al. Untangling the relationship between antiretroviral therapy use and incident pregnancy: A marginal structural model analysis using data from 47,313 HIV-positive women in East Africa. J Acquir Immune Defic Syndr. 2016 Feb 19. [Epub ahead of print] PubMed PMID: 26910499.