Evaluation of tuberculosis contact investigations in Japan

Although monitoring and evaluation using standardised indicators is an important aspect of tuberculosis (TB) contact investigation, no attempts have been made to systematically evaluate contact investigations in Japan.

To evaluate TB contact investigations conducted in public health centres (PHCs) by estimating the scores of selected indicators.

A cross-sectional study was conducted in 2012 to estimate six selected indicator scores for contact tracing, contact evaluation and contact treatment at 11 PHCs using the TB registry and relevant contact investigation records of all forms of newly notified active TB cases. Indicator scores were compared across PHCs using median and interquartile range (IQR).

A total of 2527 contacts of 313 index TB cases were identified; of these, 1874 were evaluated using the tuberculin skin test (TST) or interferon-gamma release assays (IGRAs). Of 187 contacts who were TST/IGRA-positive, 15 were diagnosed with active TB. Consistently higher medians and lower IQRs were obtained for indicators of contact tracing and contact evaluation than those of contact treatment.

Our study is the first to evaluate the performance of TB contact investigations in Japan using standardised indicators; the study indicated performance gaps, especially in the treatment for latent tuberculous infection among contacts.