(268) Impact of National Public-Private Mix and Medical Expense Support Program for Control Tuberculosis in South Korea: An Interrupted Time Series Analysis

Background: Tuberculosis (TB) remains a major threat to global public health, and various measures at national level have been implemented to control TB spread and establish patient support. Specifically, many countries with a high TB burden have been implementing TB control programs such as Public-Private Mix (PPM).

Objectives: The aim of our study was to investigate the impact of national TB control programs in South Korea using a nationwide-linked database with interrupted time series (ITS) analysis.

Methods: We identified individuals diagnosed with TB in the National Health Insurance System (NHIS) database between 2002 and 2020. The interventions of interest were PPM and MES, which were launched in January 2007 and April 2011, and expanded in January 2011 and July 2016, respectively. Using ITS analysis, we compared the following measures before and after each point of intervention: TB incidence, mortality, proportion of treatment days covered (PDC), adherence to initial regimen and frequency of medical visits. All the control measures were presented overall and stratified by age group.
For assessing the effectiveness of national TB control programs, we conducted nationwide ITS analysis based on segmented linear regression.We modelled the ITS to include monthly changes and trends for each measure by four points of intervention. The changes aimed to assess the instantaneous impact of TB control programs, and the trends estimated whether differences were observed in pre- and post-interventions. In addition, seasonal dummy variables (December to February, March to May, June to August and September to November) were included in all models to account for seasonal trends.

Results: There were 631,758 individuals diagnosed with TB between 2004 and 2020. Following the PPM, there were monthly declines of -0.04 (95% confidence interval [CI], -0.06 to -0.03) and -0.01 (-0.02 to -0.01) for TB incidence and mortality rates, respectively, and -0.05 (-0.05 to -0.04) and -0.02 (-0.02 to -0.01) after PPM expansion in 2011, respectively. Adherence to initial regimen improved following PPM initiation (+0.19 [95% CI 0.13-0.24]) and expansion (+0.21 [0.14-0.27]). Proportion with PDC >80% and frequency of medical visit also increased following PPM initiation (+0.11 [0.07-0.16], +0.06 [0.03-0.08]) and expansion (+0.10 [0.05-0.15], +0.05 [0.01-0.08]), respectively.

Conclusions: Along with the PPM, our finding suggests that relieving the economic burden of individuals living with TB may further complement in achieving the target goals of End TB strategy. For countries currently developing strategies for TB control, our results may provide important insights and future directions in effective TB control.