Baseline determinants of adherence for drug-sensitive TB treatment in a South African prospective cohort: a focus on HIV infection and anti-retroviral therapy, clinical care access, and TB stigma

Abstract

Abstract Background Suboptimal adherence to tuberculosis (TB) treatment is common and puts individuals at increased risk of treatment failure. Identifying risk factors for poor adherence may help better target individuals and improve resource allocations. We assessed specific determinants of treatment adherence: HIV status; antiretroviral therapy; time to clinical care access; and perceived stigma, among adults with drug-sensitive TB. Methods This is a secondary analysis of the “TB Mate'' cluster-randomised trial, which implemented a TB treatment adherence intervention in 18 health clinics in South Africa (PACTR201902681157721). Smart pillboxes were used to measure treatment adherence; the recording of the pillbox opening was considered a proxy for dose taken. Adults enrolled in the control arm, using the pillbox in silent mode, were eligible for this analysis. Logistic regression was used to model poor adherence (< 80% doses taken) and negative binomial regression was used to study adherence as a count of doses taken. Directed acyclic graphs guided the selection of confounders in the models. Results Out of 1,213 participants from nine clinics, 51% (614) had adherence of < 80% and the geometric mean of the percentage of doses taken was 59.6%. 63% (769) of participants were living with HIV, of whom 66% (507/769) were taking antiretroviral therapy. The median time to access clinical care was 127 minutes. Ninety-five percent (1151/1213) reported no perceived stigmatisation at the time of starting TB treatment. Living with HIV was identified as a strong determinant of adherence to TB treatment: adjusted odds ratio 1.68 (95% confidence interval [CI] 1.27–2.22) for < 80% adherence and adjusted rate ratio 0.9 (0.83–0.97) for doses taken, compared with being HIV-negative. Being on antiretroviral therapy, time to clinical care access, and perceived stigma were not associated with either adherence measure. Conclusions Very low adherence reported highlights the need for TB treatment support interventions, especially among those living with HIV.