Epidemiology of Pulmonary Nontuberculous Mycobacterial Disease, Japan1

Abstract

To the Editor: Incidence of pulmonary nontuberculous mycobacterial disease (PNTMD) is reportedly increasing globally (1,2).Although such an increase is expected in Japan (3,4), the epidemiologic situation is unclear.The most recent survey, which used the 1997 American Thoracic Society diagnostic criteria, reported that the incidence rate for PNTMD in 2007 was 5.7 cases per 100,000 personyears (5).To update the data, we performed a nationwide hospital-based survey in Japan.After a preliminary survey of 20 hospitals, we developed and disseminated questionnaires to all 884 hospitals in Japan that were certified by the Japanese Respiratory Society.The surveys asked about the number of newly diagnosed cases, from January through March 2014, of PNTMD, pulmonary Mycobacterium avium disease, M. intracellulare disease, or M. avium complex (MAC; the combination of the first 2 species listed); pulmonary M. kansasii disease; pulmonary M. abscessus disease; and tuberculosis (TB) for inpatients and outpatients.Hospital respondents returned the completed questionnaires by mail, fax, or Internet.To avoid potential reporting bias and misclassification, we counted only cases that met the 2007 American Thoracic Society/Infectious Diseases Society of America statements (6) and excluded cases diagnosed at other hospitals.Because the source population can be ascertained by using the epidemiologic data for TB as a reportable disease, to estimate the incidence rate of PNTMD, we used the ratio of TB to PNTMD cases.The PNTMD incidence rate was calculated as the national incidence rate of TB