[Use of regular check-ups after completion of treatment for latent tuberculosis infection]

To evaluate the efficacy of regular examination (primarily by chest radiography) following treatment for latent tuberculosis infection (LTBI), we attempted to estimate the frequency and time to onset of active tuberculosis after completion of LTBI treatment. OBJECTS & METHODS: From the Japanese national surveillance data of 2008-2011, we extracted and analyzed the number of active tuberculosis cases after the end of LTBI treatment that was registered during 2008-09.

Among LTBI cases registered during 2008-09 (n = 8951), 56 active tuberculosis cases following LTBI treatment were detected by the end of 2011. Frequency of onset of active tuberculosis by the end of the second year after registration of LTBI cases were as follows: 0.57% (51/8951), all active tuberculosis cases; 0.10% (9/8951), smear-positive lung tuberculosis cases; and 0.22% (20/8951), all bacteria-positive lung tuberculosis cases. In 37 active tuberculosis cases for which the date of completion of LTBI treatment was available, 12 cases were diagnosed within 1 year and 22 within 2 years of the completion of LTBI treatment.

The frequency of onset of active tuberculosis after completion of LTBI treatment was relatively low, but it did not decrease with time in the following 2 years. Hence, the validity of regular examination should be assessed, rather than specifying the duration of regular examinations after completion of LTBI treatment.