[1] Mahidol Univ, Fac Med Ramathibodi Hosp, Dept Orthoped, 270 Rama VI Road, Bangkok 10400, Thailand
[2] Mahidol Univ, Fac Med Ramathibodi Hosp, Dept Clin Epidemiol & Biostat, Bangkok 10400, Thailand
[3] Mahidol Univ, Fac Med Ramathibodi Hosp, Dept Family Med, Bangkok 10400, Thailand
[4] Chulalongkorn Univ, Fac Med, Dept Prevent & Social Med, Bangkok 10330, Thailand