[1] Univ Hong Kong, Div Resp & Crit Care Med, Dept Med, Queen Mary Hosp, Hong Kong, Hong Kong, Peoples R China
[2] AstraZeneca, Dept Epidemiol & Dis Modeling, Wilmington, DE USA
[3] Univ Penn, Clin Epidemiol Unit, CCEB, Philadelphia, PA 19104 USA
[4] Grantham Hosp, Cardiothorac Surg Unit, Hong Kong, Hong Kong, Peoples R China