<b>Adverse drug reactions in persons initiated on treatment for drug-resistant tuberculosis in Kerala, India: A non-concurrent cohort study</b>

Objectives We conducted a study to estimate the incidence of adverse drug reactions (ADRs) in the drug-resistant tuberculosis (DR-TB) cohort in Kerala in 2020 and describe the characteristics of the reported ADRs. Methods A non-concurrent cohort study was conducted among all patients with DR-TB across 14 districts in Kerala from January 1, 2020 to December 31, 2020. We collected data on ADRs from patients, "Nikshay" web-portal, treatment cards, case sheets, and registers. We described ADRs by organ system, causality, severity, preventability, predictability, and seriousness of the reaction using standard tools. Results Of the 364 persons initiated on treatment, 304 (83.5%) had at least one of the 28 listed adverse reactions, with an incidence of 27.6 ADR per 100 person-months of treatment. Gastrointestinal disorders had the highest incidence 365 per 1046 (35%). A total of 1001 of 1046 (95.7%) ADRs were non-predictable, and 405 of 1046 (39%) were definitely preventable. A total of 83 of 304 (27.3%) patients had severe ADR, and 56 of 304 (18.4%) had serious ADR. A total of 87 of 304 (28.6%) patients with ADR required interruption of the probable offending drug, with 64 of 87 (73.6%) temporary and 23 of 87 (26.4%) permanent interruptions. Conclusions Four-fifths of all patients on therapy had at least one of the 28 listed adverse reaction and one-fifth had serious ADR. ADRs can lead to treatment interruptions. Early detection and prompt management is essential for improving treatment outcomes in patients with DR-TB.