Abstract
BACKGROUND: Treatment completion is essential for the effectiveness of any latent tuberculosis infection (LTBI) regimen. The Tuberculosis Trials Consortium (TBTC) Study 33 (iAdhere) combined self-report and pill counts - standard of care (SOC) with a medication event monitoring system (MEMS) to determine treatment completion for 12-dose once-weekly isoniazid and rifapentine (3HP). Understanding the performance of SOC relative to MEMS can inform providers and suggest when interventions may be applied to optimize LTBI treatment completion. METHOD: iAdhere randomized participants to directly observed therapy (DOT), SAT, or SAT with text reminders in Hong Kong, South Africa, Spain and the United States (U.S.). This post-hoc secondary analysis evaluated treatment completion in both SAT arms, and compared completion based on SOC with MEMS to completion based on SOC only. Treatment completion proportions were compared. Characteristics associated with discordance between SOC and SOC with MEMS were identified. RESULTS: Overall 80.8% of 665 participants completed treatment per SOC, compared to 74.7% per SOC with MEMS, a difference of 6.1% (95%CI: 4.2%, 7.8%). Among U.S. participants only, this difference was 3.3% (95% CI: 1.8%, 4.9%). Differences in completion was 3.1% (95% CI: -1.1%, 7.3%) in Spain, and 36.8% (95% CI: 24.3%, 49.4%) in South Africa. There was no difference in Hong Kong. CONCLUSION: When used for monitoring 3HP, SOC significantly overestimated treatment completion in U.S. and South Africa. However, SOC still provides a reasonable estimate of treatment completion of the 3HP regimen, in U.S., Spain, and Hong Kong.