Low household income increases the risk of tuberculosis recurrence: a retrospective nationwide cohort study in South Korea

Abstract

Objectives: We assessed the impact of household income on tuberculosis (TB) recurrence and the long-term impact of TB on household income. Study design: This was a retrospective nationwide cohort study of patients with drug-susceptible TB (DS-TB) and TB recurrence. Methods: Using the South Korean national TB cohort database, we identified a sub-set cohort of patients with newly diagnosed drug-susceptible TB between 2013 and 2016 and tracked their TB recurrence and longitudinal income data from 2007 to 2018. Income levels were evaluated as Medical aid and quintile categories. To assess risk factors associated with TB recurrence, we used a sub-distribution hazard model, adjusting for the competing risks of death. Results: Of 66,690 patients successfully treated with DS-TB, 2095 (3.1 %) experienced recurrence during a median follow-up of 39 months. The incidence of TB recurrence was 982.1/100,000 person-years, with 50.3 % of the recurrences occurring within 1 year of treatment completion. The risk of TB recurrence increased with decreasing income levels, with the highest risk observed in the lowest income group. The effect of income on TB recurrence was prominent in males but not in females. Overall, patients with TB recurrence experienced a linear decline in income levels, compared with those without recurrence. Conclusions: Household income during the initial TB episode was an important risk factor for TB recurrence, particularly in males.