Multimethod analysis of adherence to preventive treatment for tuberculosis: a pragmatic randomized clinical trial

Tuberculosis Preventive Treatment (TPT) can reduce the likelihood of active disease from 1.6% to 0.6% in contacts of infectious cases. In Brazil, four therapeutic regimens for Tuberculosis infection (TBI) are currently in use, with isoniazid (INH) being the predominant regimen. The perspective of study this study is that simplifying the regimen by reducing the number of tablets required per dose could lead to improved adherence to TPT. Therefore, in 2018, the INH 300 mg dosage (one tablet per day) was introduced to improve adherence, since previously, only the 100 mg presentation was available. The present study is a pragmatic randomized clinical trial to assess adherence to treatment with 300 mg INH versus 100 mg INH, which included volunteers aged over 18 years from February 2021 to July 2022. Adherence was measured in three ways: self-reported, treatment persistence and the medication possession ratio (MPR). The results demonstrated that the INH 300 mg group had lower dropout rates and higher adherence to treatment rates, although the difference was not statistically significant. The 300 mg INH group presented greater persistence, indicating a lower probability of abandonment. This study compared two presentations of INH for TPT: a control group, in which three 100 mg tablets were administered, and an intervention group, in which one 300 mg tablet was administered, and revealed several important trends. However, not all of them reached statistical significance. These findings may support the incorporation of new therapeutic strategies in the management of TBI, as well as improve regular follow-up by health professionals for people on TPT, with the aim of optimizing the results of control and elimination programs.