Effectiveness of DOT for tuberculosis treatment outcomes: a prospective cohort study in Bangkok, Thailand

SETTING: All health care centres under the Department of Health, Bangkok Metropolitan Administration. OBJECTIVES: To investigate patterns of drug administration for tuberculosis (TB) patients and to determine whether these patterns affect treatment success rates. DESIGN: In a prospective cohort study conducted during May 2004 to November 2005, newly diagnosed TB patients aged >= 15 years were enrolled after giving informed consent. The cohort was followed until treatment outcome. Structured questionnaires were used to interview patients three times: at the first visit, at the end of the intensive phase and at treatment completion. Data were also collected from treatment cards. RESULTS: Five patterns of drug administration were used in the health centres: centre-based directly observed treatment (DOT), family-based DOT, self-administered treatment (SAT), centre-based DOT + SAT and centre- + family-based DOT. The pattern of drug administration had a significant impact on treatment success (P < 0.001). Using unconditional binary multiple logistic regression controlling for confounding factors, centre- + family-based DOT had the highest success rates compared with centre-based DOT (OR 20.9, 95%CI 5.0-88.3). CONCLUSION: The pattern of drug administration impacted on treatment success. Centre- + family-based DOT, family-based DOT and centre-based DOT + SAT achieved higher rates of treatment success than the World Health Organization target. Centre-based DOT had the lowest success.