We analysed six different definitions of ‘retention in care’ for HIV-positive pregnant women enrolled in PMTCT option B+ programmes ranging from the most lenient definition using a ‘point’ retention approach to the most stringent definition using an ‘on-time adherence’ retention approach. Of the six definitions, three definitions assess retention at a single time point (‘point’ retention, WHO, and MOH). The IATT, the ‘appointment’ and the ‘on-time adherence’ retentions approaches reflect a more continuous engagement in care, where follow-up visits between initiation of ART and the endpoint date are considered.
As expected, we found that the more stringent the definition, the lower the probability for women to be defined as retained in care; and when levels of attendance to visits during follow-up were considered, estimates were even lower (85% and 60% when using the WHO and MOH definitions compared to 16% and 1% when using the IATT and ‘on-time adherence’ retention definitions). At the end of the first year, most women starting ART had not adhered to their scheduled visits, with median appointment adherence at 66% and median on-time adherence at 40% among the 16,840 women considered as retained in care using the ‘point’ retention definition. Of these, only 16% and 2% were actually defined as retained in care 12 months post-ART initiation, if we considered a threshold of ≥75% for appointment and on-time attendance, respectively.
Initial visits in the first year of ART initiation are critical to ensure successful engagement in care, involving intensive counselling, peer support, conveying important preventive healthcare and risk reduction messages, and monitoring patterns of healthier behaviour for the women and their exposed children. This interaction between the health system and the HIV-infected women determines the likelihood of survival of the pair and the mother-to-child transmission of HIV. Adding the frequency and regularity of visits into the concept of retention increases the quality of the PMTCT programme evaluations, enabling a distinction to be made between women who attend for all or some care and treatment, and those who completely fail to adhere to scheduled visits and are therefore considered not to be engaged in care.
Table 3 provides a summary of the advantages, limitations, and programmatic implications of the six measures of retention concerning the PMTCT option B+ programmes (10,11). Based on our results, the three-single time point measures, namely, the ‘point’, WHO, and MOH definitions, were a classical programmatic approach to measure retention in care under ART. While relatively easy to use, they do not capture important milestones in the PMTCT context; for example, at delivery, at 2-months post-partum for early infant diagnosis, or at the end of breastfeeding for the final HIV determination of the HIV-exposed infant. In addition, they do not consider visit consistency, which has been demonstrated to be significantly associated with ART adherence and viral suppression among HIV-positive adults (17,18). However, the three definitions that capture visit consistency along the continuum of care, namely, the IATT, ‘appointment’ and ‘on-time adherence’ definitions, were more complex to use as they included multiple clinic visits (repeated measures) occurring longitudinally over time. This could become extremely challenging in limited-resource settings where limited qualified human resources are available to document such information, data collection tools are not adapted to capture longitudinal follow-up, and there are numerous entry points where women are followed within the same health facility or between sites (11,19). To correctly capture patients’ follow-up, different data sources need to be combined or triangulated, for example, with counselling registers and with laboratory or pharmacy records. Electronic databases may help this process, but these are generally implemented in high volume and accessible sites and may not necessarily be representative of the entire country for national programmes. However, all three definitions enabled adding the concept of a continuum of care to point retention estimates.
When considering ‘on-time adherence’ retention as the gold standard, all other definitions provided very low sensitivity rates to accurately detect patients retained in care, with high rates of misclassified patients. The WHO and MOH retention definitions provided the lowest sensitivity rates, that is, 3% and 4%, respectively. For the ‘point’ retention, WHO, and MOH definitions, which did not consider continuous follow-up in their calculations, the proportion of misclassified patients ranged from 54% to 97%. The ‘appointment adherence’ definition provided the highest sensitivity rate (11.7%), with a fairly low proportion of misclassified patients (18.3%) compared to all other definitions analysed. We found that the median time to first failure of correct follow-up was short (≤3 months), if visit attendance during follow-up was considered, which demonstrated the need to implement early preventive measures to avoid patients on the PMTCT programme disengaging from care. Such strategies should focus on already well-known barriers to regular attendance, such as a lack of disclosure, poor staff attitudes, competing personal priorities, medication side-effects, or transport difficulties (16).
While our definition of ‘on-time adherence’ retention represents the ideal situation in which an HIV-positive pregnant woman enrols in a PMTCT programme and starts ART under option B+ should be considered as fully engaged in care to ensure an optimal viral response, it is perhaps too stringent for PMTCT programme evaluations. It is also time consuming to use on a routine basis and may not be compatible with current PMTCT service settings. Therefore, we recommend either using the IATT or the ‘appointment adherence’ retention definitions to better measure levels of engagement in care for mother-infant pairs.
Our analysis had several limitations. To accurately evaluate attendance at scheduled visits, it is desirable to distinguish visits cancelled in advance (either by the patient or the care provider) from ‘no show’ visits that are actually visits missed by the patient (10). Our data did not allow this distinction to be made as this information was not captured in the database. Therefore, our results may have underestimated the real values of women’s engagement in care when analysing ‘appointment’ and ‘on-time’ adherence retentions.
Some women, although defined as having a full attendance at scheduled visits, did not follow per se the recommended schedule of visits as per national guidelines. More frequent visits may indicate a more advanced HIV disease, problems in counselling that need to be addressed, or drug or laboratory reagent stock-outs (19). Less frequent clinical visits may reflect a stabilised disease stage or temporary silent transfers (i.e. women receiving ART services elsewhere for a short period of time). For this reason, we chose to use all scheduled visits, regardless of whether the visits fell into expected time intervals. We did not analyse treatment interruptions and gaps in care for similar reasons. Further research is warranted to investigate the effect of a lack of observation of the recommended schedule of visits as per national guidelines on PMTCT programme outcomes.
Finally, we analysed data from health facilities with ePLD in two provinces in Mozambique. Although these two provinces are among the most populated in the country, with large volumes of patients seen at health facilities, our results may not be generalisable to other regions in Mozambique or to other resource-limited settings.