[1] Ryugasaki Saiseikai Hosp, Div Resp Med, Ryugasaki, Japan
[2] Ibaraki Cent Hosp, Resp Ctr, Kasama, Ibaraki, Japan
[3] Tsuchiura Kyodo Gen Hosp, Div Resp Med, Tsuchiura, Ibaraki, Japan
[4] Tsuchiura Kyodo Gen Hosp, Div Thorac Surg, Tsuchiura, Ibaraki, Japan
[5] JA Toride Med Ctr, Div Resp Med, Toride, Japan
[6] Hitachi Gen Hosp, Div Resp Med, Hitachi, Ibaraki, Japan
[7] Hitachi Gen Hosp, Div Thorac Surg, Hitachi, Ibaraki, Japan
[8] Mito Med Ctr, Div Resp Med, Mito, Ibaraki, Japan
[9] Ibarakihigashi Hosp, Div Resp Med, Tokai, Ibaraki, Japan
[10] Tsukuba Mem Hosp, Div Thorac Surg, Tsukuba, Ibaraki, Japan
[11] Tsukuba Med Ctr Hosp, Div Resp Med, Tsukuba, Ibaraki, Japan
[12] Tokyo Med Univ, Div Resp Med, Ibaraki Med Ctr, Ami Machi, Tokyo, Japan
[13] Tokyo Med Univ, Div Thorac Surg, Ibaraki Med Ctr, Ami Machi, Tokyo, Japan
[14] Kasumigaura Med Ctr, Div Resp Med, Tsuchiura, Ibaraki, Japan
[15] Univ Tsukuba, Mito Med Ctr, Mito Kyodo Gen Hosp, Div Resp Med, Mito, Ibaraki, Japan
[16] Univ Tsukuba, Fac Clin Med, Tsukuba, Ibaraki, Japan