(SLA-002) Dynamic patterns of Antiretroviral Therapy Adherence among Newly Treated People living with HIV: a Group-Based Trajectory Modeling using Real-World Data in Belgium

Background: People living with HIV (PLWH) face many challenges in adherence to antiretroviral therapy (ART). Measuring adherence during follow-up is a reliable indicator for monitoring the quality of care provided and is necessary for controlling the economics costs associated with caring for people living with HIV (PLWH). So, it is important to understand individual change in adherence during follow-up in order to guide decision-making for a personalized approach to the care of PLWH.

Objectives: This study aimed to identify different ART adherence trajectories during 24-month follow-up among newly treated PLWH between 2019 and 2022 in Belgium.

Methods: A retrospective analysis of longitudinal pharmacy claims was conducted using the Pharmanet database from July 1, 2019, to December 31, 2022, among adult PLWH in Belgium who were newly initiated on ART. Adherence was assessed every month during the 24 first months of follow-up and reported as the proportion of days covered (PDC). Group-based trajectory modeling (GBTM) was conducted to identify adherence trajectories.

Results: We included 2226 PLWH, predominantly male (64.7%), aged between 35 and 49 (42.7%), and resident in the Flanders region (46.8%). Four adherence trajectories were identified, namely “consistently high” (n = 1283; 57.0%), “decreasing then increasing” (n = 403; 19.0%), “gradually decreasing” (n = 291; 12.9%) and “early decreasing” (n = 249; 11.1%). Compared with the “consistently high” adherence trajectory group, the proportion of women (30.5% to 48.2%), older people (6.2% to 10.4%) and living in Brussels-Capital region (25.9% to 30.1%) was higher in the “early decreasing” adherence trajectory group.

Conclusions: Adherence to antiretroviral treatment remains a challenge for PLWH, especially during periods of health system disruption and when treatment is taken over a long period. Qualitative studies followed by multi-level behavioral interventions are needed to understand the dynamics of adherence and improve it in Belgium.