Background
As cycling in and out of HIV care over time becomes the norm for people with HIV, most commencing antiretroviral therapy are now restarting rather than initiating treatment for the first time. Understanding patterns of engagement after a substantial treatment interruption could help to direct service implementation and choice of interventions for this crucial population, and help make progress in controlling the epidemic.
Methods
Using routine health data from the Western Cape Provincial Health Data Centre, South Africa, we analysed individuals ≥15 years old who initiated treatment after 01-Sep-2016, sought care in low-resource, high-HIV burden settings, and had ≥5 yearsfollow-up before database closure (30-Sep-2022). Group-based trajectory modelling identified subgroups with distinct longitudinal engagement patterns from the time of restarting therapy after a treatment interruption (disengagement defined using pharmacy refill data as a treatment interruption >90 days). Logistic regression assessed subgroup associations with viral suppression ≤1000 copies/mL.
Results
The cohort (n=2150) was 71% female with median of age 30 years (IQR 25-36) at initiation. The best-fitting model identified five subgroups of engagement over five years after restart (figure): 1) Optimal engagement (30%); 2) Rapid disengagement (25%); 3) Early disengagement (16%); 4) Delayed disengagement (12%); and 5) Disengagement with return (17%). Nearly half (47%) disengaged again within the first year, but most (70%) disengaged again within five years of return. Subgroups were similar in age, sex, comorbidities, baseline CD4 count, and duration on treatment, with no variables strongly predictive of subgroup membership. Subgroups were strongly associated with lower odds of viral suppression at 5 years compared to the optimally engaged subgroup (adjusted odds ratio [95% confidence interval]: 0.09 [0.04-0.09], 0.11 [0.05-0.22], 0.16 [0.10-0.29] and 0.61 [0.39-0.97] for subgroups 2, 3, 4, and 5 respectively).
Conclusions
Most people returning to care after a substantial treatment interruption disengaged again within five years from restart, with high rates of early drop out. However, disengagement followed a range of patterns with differing associations with viral suppression. These patterns may be useful to help target interventions to subgroups with similar engagement behaviours, but require further exploration to operationalise the patterns in the data and use these findings to inform decisions on service delivery.