Measuring retention in care for HIV-positive pregnant women in Prevention of Mother-to-Child Transmission of HIV (PMTCT) option B+ programs: the Mozambique experience

BACKGROUND: Failure to retain HIV-positive pregnant women on antiretroviral therapy (ART) leads to increased mortality for the mother and her child. This study evaluated different retention measures for women’s engagement along the continuum of care for prevention of mother-to-child transmission (PMTCT) option B+ services in Mozambique. METHODS: We compared ‘point’ retention (patient’s presence in care 12-month post-ART initiation or any time thereafter) with the following definitions: alive and in care 12 month post-ART initiation (Ministry of Health; MOH); attendance at a health facility up to 15-month post-ART initiation (World Health Organization; WHO); alive and in treatment at 1-, 2-, 3-, 6-, 9-, and 12-month post-ART initiation (Inter-Agency Task Team; IATT); and alive and in care 12-month post-ART initiation with ≥75% appointment adherence during follow-up (i.e. ‘appointment adherence’ retention) or with ≥75% of appointments met on time during follow-up (i.e. ‘on-time adherence’ retention). Kaplan-Meier survival curves were produced to assess variability in retention rates. We used ‘on-time adherence’ retention as our reference to estimate sensitivity, specificity, and proportion of misclassified patients. RESULTS: Considering the ‘point’ retention definition, 16,840 HIV-positive pregnant women enrolled in option B+ PMTCT services were identified as ‘retained in care’ 12-month post-ART initiation. Of these, 60.3% (95% CI 59.6–61.1), 84.8% (95% CI 84.2–85.3), and 16.4% (95% CI 15.8–17.0) were classified as ‘retained in care’ using MOH, WHO, and IATT definitions, respectively, and 1.2% (95% CI 1.0–1.4) were classified as ‘retained in care’ using the ‘≥75% on-time adherence’ definition. All definitions provided specificity rates of ≥98%. The sensitivity rates were 3.0% with 78% of patients misclassified according to the WHO definition and 4.3% with 54% of patients misclassified according to the MOH definition. The ‘point’ retention definition misclassified 97.6% of patients. Using IATT and ‘appointment adherence’ retention definitions, sensitivity rates (9.0 and 11.7%, respectively) were also low; however, the proportion of misclassified patients was smaller (15.9 and 18.3%, respectively). CONCLUSION: More stringent definitions indicated lower retention rates for PMTCT programs. Policy makers and program managers should include attendance at follow-up visits when measuring retention in care to better guide planning, scale-up, and monitoring of interventions.