(267) Impact of medication adherence to active tuberculosis occurrence in pediatric population with latent tuberculosis infection: A population-based cohort study in South Korea

Background: Research on the incidence of active tuberculosis in pediatric populations undergoing tuberculosis preventive therapy (TPT) regimens is insufficient. Particularly, there is a scarcity of studies focusing on medication adherence in this context

Objectives: To examine the association between medication adherence to three tuberculosis preventive therapy (TPT) regimens and TB incidence in pediatric population with latent tuberculosis infections (LTBI).

Methods: This study applied retrospective cohort study using Korean national health insurance data. Pediatric population with newly diagnosed with LTBI between 2015 and 2020 was participated. TB incidence was compared among the different TPT regimens [i.e. (9 months of treatment with isoniazid (9H); 4 months of treatment with rifampicin (4R), and 3 months of treatment with isoniazid and rifampicin (3HR) )]. Treatment adherence was evaluated using the medication possession ratio (MPR). TB was identified with International Classification of Disease (ICD)-10 diagnostic codes and anti TB medicines. The prevalence of TB was defined if TB manifested within 3 months following the diagnosis of LTBI, and incidental active TB was considered subsequent to that timeframe. Cox proportional hazards models were used to examine the effects of medication adherence of TPT regimen after adjustment of potential confounders such as age, close contact, sex, type of insurance, type of healthcare provider, and presence of comorbidities.

Results: The study examined a cohort of 13,881 pediatric individuals with LTBI over an average follow-up period of 3.8 years. The majority utilized 9H regimen (n=8,114, 58.5%) and followed by 3HR (n=5,113, 36.8%) and 4R (n=654, 4.7%). Participants in the 9H group exhibited a higher prevalence of close contact with active TB cases and were younger compared to those in the 4R or 3HR groups. A total of 36 (0.26%) active TB cases reported, including 11 (0.08%) prevalent TB and 25 (0.18%) incident TB. Incidence rate per 100,000 person-year (PY) was 34 for 9H, 74 for 3HR, and 49 for 4R. Non-adherence (MPR < 80%) rates were 42% for 9H, 14% for 3HR, and 19% for 4R. Adherence to TPT with an MPR ≥80% was associated with a risk reduction of TB incidence by up to 70% compared to non-adherence (MPR < 80%).

Conclusions: This study highlights the critical importance of medication adherence in preventing tuberculosis among pediatric individuals with LTBI.