Adherence to tuberculosis preventive therapy among HIV-infected persons in Chiang Rai, Thailand

Objective: To determine the level of and reasons associated with adherence to tuberculosis preventive therapy among asymptomatic HIV-infected individuals in northern Thailand. Design: A prospective cohort study with a 9-month follow-up. Methods: A total of 412 HIV-infected persons were enrolled in a tuberculosis preventive therapy programme in a hospital. A 9-month isoniazid regimen was prescribed. Adherence was determined by pill count. Participants who missed a scheduled appointment for more than a month were interviewed. Five focus group discussion sessions were held among those who successfully completed the therapy. Results: Of the 412 participants, 69.4% (286) completed the 9-month regimen. The adherence rate, defined as the proportion of those who took more than 80% of pills, was 67.5% (n=278). Sex, source of participants and history of physical symptoms were associated with adherence. A significant portion of defaults took place at the beginning of the therapy. Out-migration, denial of HIV status, and perceived side effects of isoniazid were frequently cited as reasons for non-adherence. For those adhering participants, the acceptance of personal HIV status, concern about children and family, and a good health provider relationship were important reasons motivating adherence. Several reminder systems were developed by the participants. Conclusions: Although an isoniazid preventive therapy programme was shown to be feasible, further adjustments on the selection of participants, enrolment process, and follow-up system based on these findings are necessary to increase the adherence.