Baseline characteristics according to body mass index.

Continuous variables are presented as medians (interquartile ranges).Categorical variables are presented as frequencies (%).*CPF included the condition of permanent shortness of breath on light activity due to pulmonary disease, and functionally, the patients are unable to work, to climb stairs or perform household duties.†Observational reason for ICU admission was defined as the preparation for routine post-surgery care including simple weaning from ventilator after surgery.CPF, chronic pulmonary disease; DM, diabetes mellitus; CRF, chronic renal failure; ICU, intensive care unit; SS, severe sepsis; ARDS, acute respiratory distress syndrome.