Factors associated with declining numbers of chronic tuberculosis excretors in Japan.

SETTING: Japan's National Tuberculosis Programme (NTP). OBJECTIVES: To determine and assess the chronological change of chronic excretors. DESIGN: We compared two groups of chronic excretors (continuous excretion of TB bacilli in the last 2 years) classified by time of registration; the first group was registered from 1991 to 1997, and the second from 1998 to 2004. The epidemiological situation and the NTP were also compared. RESULT: There were 481 cases in the first group, comprising 0.17% of registered cases, and 159 cases in the second group, comprising 0.06%. Stratified analysis by treatment regimen and TB category confirmed a decrease in the ratio of chronic excretors in all sub-groups. Human factors such as non-adherence, no drug susceptibility testing (DST) on initiation of treatment and inadequate modification of treatment in new sputum smear-positive cases were more frequent in the first group than in the second (37.0% vs. 28.9%, 19.5% vs. 10.7%, 36.8% vs. 19.5 %, P < 0.05). Other known risk factors, such as interruption due to side effects and complication of diabetes and/or alcoholism, were similarly distributed. CONCLUSION: The decline in chronic excretors has been associated with the DOTS strategy, baseline DST and appropriate modification of treatment regimen in new sputum smear-positive cases.