[1] Chiang Mai Univ, Fac Med, Dept Internal Med, 110 Intawaroros Rd,Sriphoom, Muang Chiang Mai 50200, Thailand
[2] Chulalongkorn Univ, Fac Med, Dept Internal Med, Bangkok, Thailand
[3] Cent Chest Inst Thailand, Nonthaburi, Thailand
[4] Mahidol Univ, Golden Jubilee Med Ctr, Dept Med, Nakhon Pathom, Thailand