Impact of COVID-19 on tuberculosis mortality in Japan: a retrospective analysis of national surveillance data from 2017 to 2022

Background The coronavirus disease 2019 (COVID‑19) pandemic and the associated public health and social measures have disrupted tuberculosis (TB) services globally. However, the impact of the pandemic on TB mortality in Japan has not been examined. This study assessed trends in TB mortality before and during the COVID‑19 pandemic and evaluated whether being diagnosed during the pandemic influenced TB mortality. Methods We analyzed anonymized, individual‑level cohort data for all patients notified with active TB to the national TB surveillance system between 1 January 2017 and 31 December 2022. TB mortality rates were estimated for the pre‑COVID‑19, pre‑Omicron, and Omicron variant‑dominant periods. Cox proportional hazards models incorporating a time‑varying covariate were used to examine the association between COVID‑19 period and TB mortality for the entire cohort and for patients aged 0–64 years and ≥ 65 years, with a follow-up period of 365 days. Covariates included age, sex, country of birth, diabetes status, diagnosis, mode of detection, delay, and insurance status. Results TB mortality increased from 10.1 (95% confidence interval [CI] 9.7–10.4) to 12.7 per 100 person-years (95% CI 12.0-13.5) between the pre-COVID-19 and Omicron periods. This increase was driven primarily by patients aged ≥ 65 years, whose mortality rose from 15.2 (95% CI 14.7–15.8) to 18.5 per 100 person-years (95% CI 17.4–19.7). Being diagnosed during the Omicron variant-dominant period was identified as an independent predictor of TB mortality among those aged ≥ 65 years (adjusted hazard ratio [aHR] 1.10, 95% CI 1.03–1.18, p = 0.007) but not among those aged 0–64 years (aHR 1.09, 95% CI 0.78–1.53, p = 0.606).