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Introduction: Recent international guidelines call for expanded access to triple-drug antiretroviral therapy (ART) in HIV-positive women during pregnancy and postpartum. However, high levels of non-adherence and/or disengagement from care may attenuate the benefits of ART for HIV transmission and maternal health. We examined the frequency and predictors of disengagement from care among women initiating ART during pregnancy in Cape Town, South Africa.
We conducted a retrospective cohort study of all HIV-positive women who initiated ART during pregnancy between January 2011 and September 2012, after booking for ANC at a large primary-level antenatal clinic in Gugulethu, Cape Town. The population attending this clinic is predominantly black African. Historically, all women found to be ART eligible during ANC were referred for treatment initiation at a general adult ART clinic on the same premises as the ANC facility [9, 13, 24]. In January 2012, integrated nurse-initiated and managed ART services were introduced at the antenatal clinic. After this time, all eligible women started ART in the ANC facility where they continued to receive their ART care along with ANC throughout the antenatal period. Following delivery, women with viral suppression were transferred to general adult ART services after the latter of 20 weeks on treatment or when the infant HIV status had been determined at six weeks of age. Clinical and counselling protocols did not differ significantly between the general ART and the ANC-based ART service, and counselling services were provided by the same team of counsellors during normal working hours across both ART sites. Throughout the study period, pregnant HIV-positive women who were eligible for ART were started on a combination of tenofovir with lamivudine and either nevirapine or efavirenz [25]. ART eligibility was based on CD4 cell count of ≤350 cells/µl or WHO stage III/IV disease throughout the study period and women attended 1–2 counselling sessions prior to starting ART. At both ART sites, women received a 30-day supply of ART for the first four months on treatment and a 30- or 60-day supply thereafter; follow-up visits were scheduled every 28 or 56 days, accordingly. Data for this analysis come from a review of routine medical records for all pregnant women registered in the Gugulethu antenatal clinic with documented HIV infection and who initiated ART between January 2011 and September 2012. Demographic, obstetric and clinical characteristics, as well as the ART initiation site and details of visit attendance (including dates of clinic visits, scheduled visits and quantity of ART supplied at each visit) were abstracted from clinic visit and pharmacy records at both the general adult and integrated ART facilities using standardized data abstraction tools. Data were abstracted up to 12 months on ART and missing laboratory and delivery data were obtained from routine laboratory databases. Data were analyzed using Stata 12.0 (Stata Corporation, College Station, USA). Descriptive statistics were used to summarise the baseline characteristics of the study population. Bivariate associations were calculated using Chi-squared tests for categorical variables and the Wilcoxon rank-sum test for independent samples of continuous variables. The primary exposure of interest was the site of ART initiation, analyzed as a binary variable denoting general adult ART initiation or ART initiation integrated into ANC. The quantity of ART supplied at each visit was used to determine the next expected visit date and the number of days late were calculated as the difference between the expected ART visit and the date the visit was attended. The primary outcome of disengagement from care was defined as having 56 days elapsed since the last scheduled visit with no evidence of attendance, treatment collection or transfer out (TFO) [9, 26, 27]. For the purpose of this analysis, women transferred out during the analysis period were censored at the time of transfer. Secondary analyses focused on missed visits as a marker of non-adherence, defined as being more than 14 days late for a visit but returning to care within 56 days; women who had missed a visit may have disengaged from care at a later date. In sensitivity analyses, we examined variability in the time periods used to define disengagement and missed visits, and found that realistic variations in definitions did not influence results appreciably. Antenatal person-time was accrued from ART initiation to the first of: (1) Delivery; (2) TFO or (3) disengagement. For women remaining in care postpartum, person-time accrued from the date of delivery up to the first of: (1) the end of the study period; (2) TFO or (3) disengagement. The date assigned to disengagement was the date of the last expected visit. Kaplan–Meier curves were generated to explore retention in the antenatal and postpartum periods and between the two ART initiation sites. Predictors of disengagement overall, as well as restricted to the antenatal or postpartum periods, were examined using Cox proportional hazards models, with results reported as adjusted hazard ratios (aHR) with 95% confidence intervals (CI). Variables were included in the model if they demonstrated a significant association (p<0.05) with the outcome, and/or appeared to confound the associations involving other variables. Time-varying covariates were used to examine the impact of pregnancy status (antenatal versus postpartum) on disengagement. Ethical approval to abstract data and conduct this analysis was provided by the Human Research Ethics Committee of the University of Cape Town.
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