Effectiveness of Household Contact Investigation with Preventive Therapy for Infectious Tuberculosis in an Intermediate Tuberculosis Burden Country: A Nationwide Investigation

Background: The effect of nationwide household contact (HHC) investigation with tuberculosis (TB) preventive treatment (TPT), including rifampin-resistant TB (RR-TB), in an intermediate TB burden country has not been well evaluated. Moreover, the coverage of HHC investigation with TPT is limited in low-income countries. Thus, it is important to determine the risk factors to identify the priority population for HHC investigation. Methods: This retrospective cohort study analyzed data of HHC participants registered between January 2015 and December 2018 in a linked database of nationwide TB registry and healthcare administrative claims database of South Korea. The primary outcome measure was incident active TB according to the TPT. As secondary outcome measures, we evaluated the risk factors for co-prevalent TB and latent TB infection (LTBI) among HHCs. Findings: We included 119,233 HHCs. TPT completion indicated a lower risk of active TB (adjusted hazard ratio [aHR], 0·14 [95% CI, 0·09–0·22]). Among HHCs of RR-TB patients, there was no significant difference in the risk of active TB between the LTBI-positive with TPT group and the LTBI-negative group (aHR, 2·27 [95% CI, 0·58-8·83]). Male sex, age ≥76 years, contact with first-degree relatives, comorbid chronic pulmonary disease, comorbid diabetes, and alcohol abuse correlated with a higher risk of co-prevalent TB. Further, male sex, contact with first-degree relatives, and comorbid diabetes correlated with a higher risk of LTBI. Interpretation: Nationwide HHC investigation with TPT may effective in an intermediate-TB burden country. Further, HHC with male sex, first-degree relatives, and comorbid diabetes should be prioritized for HHC investigation. Funding Information: Korea Disease Control and Prevention Agency. Declaration of Interests: We declare no competing interests Ethics Approval Statement: This study was approved by the Institutional Review Board (IRB) of Chung-Ang University (IRB number: 1041078-201801-HR-012-01). Informed consent was waived owing to the use of de-identified data.