The Impact of Isoniazid and Pyrazinamide Mono-resistance on Mortality among Tuberculosis Patients in Los Angeles County, 2010-2014

Background: Isoniazid and pyrazinamide mono-resistant tuberculosis (TB) may be associated with poor treatment outcomes, but previous studies have found conflicting results. We assessed the impact of isoniazid (INH) or pyrazinamide (PZA) mono-resistance on mortality during TB treatment in Los Angeles County. Methods: We retrospectively reviewed drug susceptibility test patterns and treatment outcomes among TB cases reported to the Los Angeles County Tuberculosis Control Program from 2010 to 2014. Multiple logistic regression was used to determine the association between isoniazid or pyrazinamide mono-resistance and death while controlling for patient characteristics.Results: Of 1,927 TB patients included in the analysis, in the multiple-logistic-regression model adjusting for age, gender, race, foreign-born, extra pulmonary status, and history of TB, patients with INH or PZA mono-resistance had higher odds of death than patients with drug-susceptible TB [OR 1.57 (0.93, 2.64); and OR 2.43 (0.92, 6.44), respectively]. Conclusion: Patients with INH or PZA mono-resistance were more likely to die than patients with drug-susceptible TB. Efforts are needed to improve treatment outcomes for INH or PZA mono-resistant TB patients.