Implementation of Latent Tuberculosis Infection in Tuberculosis Contacted Persons. In 11th health region

Abstract

This study employed a retrospective cohort design using secondary data from the Thailand National Tuberculosis Information Program (NTIP) and a structured questionnaire developed by the researcher. The study aimed to evaluate the performance of Tuberculosis Preventive Treatment (TPT) among TB contacts and identify factors associated with latent tuberculosis infection (LTBI) and treatment success among TB contacts in Health Region 11, Thailand.  The study population comprised 27,374 TB contacts who were screened for TB through the NTIP database during fiscal years 2021–2023. Results: Of the 27,374 TB contacts, 17,335 (63.32%) were household contacts and 10,039 (36.67%) were close contacts outside the household. The ratio of index TB cases to household contacts was 1:2.2. Abnormal chest radiographs were identified in 1,930 contacts (7.05%), and 696 (2.54%) were diagnosed with active TB. Among contacts aged ≥5 years who voluntarily underwent testing, the LTBI detection rate was 26.28%, comprising 25.93% IGRA-positive and 43.81% TST-positive. A total of 1,768 contacts initiated LTBI treatment. The adherence rates were 96.37% (1,168/1,212) among those aged ≥5 years and 58.36% (600/1,028) among those aged <5 years. The overall TPT completion rate was 89.48%. The highest completion was observed in the 1HP regimen (100%), followed by 4R (97.85%) and 3HP (92.15%). The factors associated with LTBI were significant. Male contacts had a 23.9% lower risk compared to females. Contacts aged 5–14 years (OR = 2.11) and 25–44 years (OR = 1.30) had higher LTBI risk compared with those aged ≥65 years. Moreover, household contacts had a 4.87-fold higher risk than non-household contacts. Regarding treatment outcomes, contacts receiving regimens other than 6-9H (i.e., 3HR, 1HP, and 4R) had roughly 48% lower likelihood of treatment completion. Therefore, the identification and follow-up of TB contacts should be prioritized to enhance early LTBI detection, reduce local TB transmission, and prevent future development of active TB.