[1] Jichi Med Univ, Dept Med, Div Pulm Med, Shimotsuke, Tochigi, Japan
[2] Minist Hlth Labour & Welf, Tokyo, Japan
[3] Kanagawa Cardiovasc & Resp Ctr, Dept Resp Med, Yokohama, Kanagawa, Japan
[4] Hamamatsu Univ Sch Med, Dept Resp Med, Shizuoka, Japan
[5] Tosei Gen Hosp, Dept Resp Med & Allergy, Seto, Aichi, Japan
[6] Univ Occupat & Environm Hlth, Dept Resp Med, Fukuoka, Japan
[7] Toranomon Gen Hosp, Dept Resp Med, Tokyo, Japan