The risk of viral rebound in the year after delivery in women remaining on antiretroviral therapy

Objective: The objective of this study is to assess the risk of viral rebound in postpartum women on suppressive combination antiretroviral therapy (cART). Methods: Using data from the UK Collaborative HIV Cohort (UK CHIC) study and the UK and Ireland National Study of HIV in Pregnancy and Childhood (NSHPC), women with HIV-RNA 50copies/ml or less at delivery in 2006-2011, who started life-long cART during pregnancy (n=321) or conceived on cART (n=618), were matched by age, duration on cART and time period, with at least one control (non-postpartum). The cumulative probability of viral rebound (HIV-RNA >200copies/ml) was assessed by Kaplan-Meier analysis; adjusted hazard ratios (aHRs) for the 0-3 and 3-12 months postdelivery (cases)/pseudo-delivery (controls) were calculated in Cox proportional hazards models. Results: In postpartum women who conceived on cART, 5.9% [95% confidence interval (95% CI) 4.0-7.7] experienced viral rebound by 3 months, and 2.2% (1.4-3.0%) of their controls. The risk of viral rebound was higher in postpartum women than in controls during the first 3 months [aHR 2.63 (1.58-4.39)] but not during the 3-12 months postdelivery/pseudo-delivery. In postpartum women who started cART during pregnancy, 27% (22-32%) experienced viral rebound by 3 months, and 3.0% (1.6-4.4%) of their controls. The risk of viral rebound was higher in postpartum women than in controls during both postdelivery/pseudo-delivery periods [<3 months: aHR 6.63 (3.58-12.29); 3-12 months: aHR 4.05 (2.03-8.09)]. Conclusion: In women on suppressive cART, the risk of viral rebound is increased following delivery, especially in the first 3 months, which may be related to reduced adherence, indicating the need for additional adherence support for postpartum women.