Definition of abbreviations: APACHE IV = Acute Physiology and Chronic Health Evaluation IV; BMI = body mass index; COPD = chronic obstructive pulmonary disease; DM = diabetes mellitus; IPA = invasive pulmonary aspergillosis; LOS = length of stay; ODI = optical density index; PF = PaO2/FiO2; pred mort = predicted mortality.
Data are expressed as mean [95% confidence interval] unless stated otherwise.
*  P < 0.05.