Isoniazid preventive treatment: predictors of adverse events and treatment completion

SETTING: Villa Marelli Institute (VMI), Niguarda Ca'Granda Hospital, Milan, Italy. BACKGROUND: A recent report on the fatal side effects of isoniazid preventive therapy (IPT) from the United States has re-ignited discussion on the safety of this intervention. OBJECTIVE: To evaluate IPT feasibility, treatment completion and adverse events (AE) and their determinants under field conditions. METHODS: Data from consecutive subjects undergoing IPT at the VMI were recorded in an electronic database from 1992 to 2009. Logistic regression analysis was performed to detect completion and AE determinants. RESULTS: A total of 11 963 patients were included in the study. AE (odds ratio [OR] 2.70, 95 % CI 2.22-3.28) and human immunodeficiency virus positive status (OR 5.20, 95 % CI 2.10-12.93) were the main determinants of treatment interruption among Italians, while social weakness (no housing/job; OR 2.88, 95 % CI 2.43-3.42), AEs (OR 1.33, 95 % CI 1.15-1.53, 2.22-3.28) and screening in undocumented subjects (OR 1.20, 95% CI 1.01-1.44) prevailed among foreigners. Age was the main determinant of transaminase increase (OR 1.03, 95% CI 1.03-1.04), as were AEs of the gastrointestinal (OR 1.02, 95 % CI 1.02-1.03), central nervous (OR 1.02, 95 % CI 1.02-1.05) and peripheral nervous systems (OR 1.04, 95% CI 1.02-1.05). CONCLUSION: This analysis demonstrates the feasibility and safety of IPT, with determinants of interruption and AEs being predictable and addressable.