Treatment Adherence With an Oral 9-Month Regimen for Rifampicin-Resistant Tuberculosis in South Africa

BACKGROUND: Adherence to anti-tuberculosis (TB) therapy is an important determinant of treatment outcome in rifampicin-resistant tuberculosis (RR-TB). Understanding adherence to contemporary treatment regimens in routine care is needed to support implementation in TB programs. We aimed to characterize temporal adherence patterns among people receiving oral treatment for RR-TB. METHODS: We conducted a prospective observational cohort study at a referral TB hospital in South Africa. People aged ≥15 years with pulmonary RR-TB starting an oral 9- to 12-month regimen were included. Treatment adherence was measured using a digital pillbox during ambulatory care and with directly observed therapy during hospital care. The primary outcome was proportion of adherence days through 9 months. Latent class group-based trajectory modeling was used to identify temporal adherence patterns. RESULTS: Of 248 participants, 209 (84.3%) had assessable adherence data from the digital pillbox or directly observed therapy. Overall median adherence was 82% (interquartile range [IQR], 63%-98%) with combined measures, and 72% (IQR, 51%-92%) with digital pillbox only. Four distinct adherence patterns were identified. Adherence was 93%-100% in the first month. Two groups, representing 136 (65.1%) individuals, had small reductions in adherence over time, separated by higher and lower early adherence. In the other 2 groups, there was a 50% reduction in adherence by month 3 (48/209 [23.0%]) and month 6 (25/209 [12.0%]), respectively. Lower adherence over time was associated with having exclusive ambulatory care, treatment with the shorter regimen only, and age