Trend and treatment status of latent tuberculosis infection patients in Japan – Analysis of Japan TB Surveillance data

Objective and method: Management of latent tuberculosis infection (LTBI) is one of the core elements of End TB Strategy. Japan is one of the few countries in which notification of LTBI is mandatory, yet so far, the data has not been analyzed in detail. We thus conducted a cross-sectional study to examine the trend of LTBI, its treatment outcome and factors predicting treatment non-completion in Japan for the period of 2007 and 2014, using the data from the electronic Japan Tuberculosis Surveillance system. Treatment completion was defined as those whose reason for terminating the treatment was recorded as “treatment completed” and whose treatment duration was 180 days or more. Results: During the study period, a total of 50,268 LTBI patients were notified, of which 49,525, who had started treatment, were analyzed for characteristics. 57.5% were females, and 38.5% were aged 25–44 years. As for the job category, healthcare professionals, that is medical doctors, nurses and other healthcare workers, consisted the largest group (30.4%). Overall, the number of LTBI notification has been on an increase, with a large increase observed among those aged 65 years and above. Of the 49,525 patients, the information regarding reason for termination of treatment was available for 46,128 (93.1%). Of them, 33,156 (71.9%) had completed treatment as according to the study definition. The risk factors for not completing LTBI treatment included being aged 65 years and above (adjusted odds ratio [aOR] 1.27, 95% confidence interval [95%CI] 1.10–1.47), foreign-born (aOR 1.14, 95%CI 1.02–1.28), healthcare professional (aOR 1.44, 95%CI 1.24–1.69), full-time and part-time worker (aOR 1.40, 95%CI, 1.20–1.63) and detected via contact investigation (aOR 1.26, 95%CI 1.12–1.41). Conclusions: Our study results revealed that the treatment completion rate was 71.9%, falling short of the national target of 85%, and also that the treatment duration was recorded as less than 180 days for approximately 20% of those who were reported as having completed treatment. Further studies may be built on ours to explore the reasons for not completing the treatment across different population groups, and identify those who benefit the most, and who has the greatest impact on ending TB, by receiving LTBI treatment.