NPPB and chronic obstructive pulmonary disease: We initially included key variables that potentially affect risk of mortality and progression to intubation such as age, sex, comorbidities (chronic obstructive pulmonary disease [COPD], heart failure [HF], Diabetes mellitus [DM], chronic kidney disease [CKD], hypertension[HTN]), baseline laboratory values (C Reactive Protein [CRP] (> 100 mg/L or <  = 100 mg/L), Troponin I (> 28% or <  = 28%), NT–proBNP (> 88 pg/mL or <  = 88 pg/mL), Lymphocyte Count (> = 1.0 μL or < 1.0 μL) and Creatinine (< = 1.5 mg/dL or > 1.5 mg/dL).