Trend and treatment outcomes of latent tuberculosis infection among migrant persons in Japan: analysis of Japan Tuberculosis Surveillance data

Background Screening for latent tuberculosis infection (LTBI) among migrant population has become a critical issue for many low TB burden countries. Evidence regarding effectiveness of LTBI programs are limited, however, partly because of paucity of national data on treatment outcomes for LTBI. In Japan, notification of LTBI is mandatory, and its treatment outcome is reported as part of Japan’s national TB surveillance system. We thus conducted a detailed analysis of LTBI among foreign-born persons, to update the epidemiological trend of newly notified LTBI between 2007 and 2018, and, to examine the treatment regimen and outcome of those notified in 2016 and 2017, focusing specifically on the potential risk factors for lost to follow-up. Methods We analyzed the data of newly notified LTBI patients to examine the overall trend of notification and by age groups and modes of detection between 2007 and 2018, and the cohort data for treatment regimen and outcomes of foreign-born persons notified with LTBI in 2016 and 2017. Potential reasons for lost to follow-up were explored, and logistic regression analysis was conducted to identify risk factors. Comparisons were made with the Japan-born patients where appropriate. Results Both the number and proportion of LTBI among foreign-born persons have been constantly increasing, reaching 963 cases in 2018. Analysis of cohort data indicated that the proportion of those on shorter regimen was higher among the foreign- than Japan-born patients (5.5% vs. 1.8%, p < 0.001). The proportion of those who have been lost to follow-up and transferred outside of Japan combined was higher among the foreign- than Japan-born patients (12.0% vs, 8.2%, p < 0.001). Risk factors for lost to follow-up were being employed on a temporal basis, and job status unknown (adjusted odds ratios 3.11 and 4.09, 95% confidence intervals 1.34–7.26 and 1.60-10.48, respectively). Conclusions Migrant population face greater risk of interrupting LTBI treatment, and interventions to improve adherence are a critical component of programmatic management of LTBI. Further studies are needed to explore the cultural and socioeconomic situation in which foreign-born persons undergo LTBI treatment in Japan.