Factors associated with treatment adherence in a randomised trial of latent tuberculosis infection treatment

Abstract

Setting: Randomised controlled trial of latent tuberculosis infection (LTBI) treatment in 10 clinics in Canada, Saudi Arabia and Brazil.

Objective: To identify early predictors of LTBI treatment adherence, including pre-treatment characteristics.

Design: Patients randomised to 4 months of rifampicin (RMP; n = 420) or 9 months of isoniazid (n = 427) were monitored for adherence using an electronic device. Outcomes were 1) treatment completion, defined as intake of >or=80% of the prescribed doses, and further categorised as completed within the allotted time or not; and 2) treatment regularity, measured by the time interval between doses. Relative risk (RR) and adjusted odds ratios (aOR) of patients' pre-treatment characteristics and adherence at first follow-up visit were calculated.

Results: Completion of treatment was higher with RMP (aOR 4.3, 95%CI 2.7-6.8). Early predictors (first follow-up visit) of non-adherence were late first visit attendance (RR for completion in time 0.9, 95%CI 0.8-0.98), >20% of missed doses (RR 0.4, 95%CI 0.3-0.6) and greater variation of hours between doses (0.209 vs. 0.131, P < 0.001). Serious adverse events were not associated with irregularity of treatment.

Conclusion: The shorter RMP regimen was associated with better adherence. Patients with poor adherence could be identified at the first follow-up visit from their punctuality in follow-up, missed doses and variability of pill-taking.