Table 1

Baseline characteristics of the intention-to-treat population

High flowConventional
Nasal oxygenOxygen therapy
 Sex, no (%)
 Female62 (34.3)69 (38.1)
 Male119 (65.7)112 (61.9)
 Age (years), mean (SD)59.01 (14.88)58.92 (14.77)
 BMI (kg/m2), mean (SD)28.55 (4.33)27.99 (4.45)
Clinical characteristics related to acute respiratory failure
 SpO2 (%), mean (SD)89.63 (2.62)89.87 (2.78)
 Respiratory rate (breaths/min), mean (SD)21.53 (3.32)21.62 (3.56)
 Dyspnoea score,* median (IQR)2 (2–3)3 (2–3)
Comorbidities, no (%)
 History of acute myocardial infarction8 (4.4)8 (4.4)
 Chronic heart failure11 (6.1)10 (5.5)
 Cerebrovascular disease3 (1.7)3 (1.7)
 Chronic obstructive pulmonary disease18 (9.9)19 (10.5)
 Diabetes18 (9.8)26 (14.2)
 Moderate to severe chronic kidney disease†6 (3.3)6 (3.3)
 Moderate to severe liver disease‡2 (1.1)3 (1.7)
 Cancer§6 (3.4)4 (2.3)
 Obesity¶60 (33.1)58 (32.0)
 At least one comorbidity,** no (%)
  None80 (44.2)76 (42.0)
  At least one101 (55.8)105 (58.0)
 Charlson comorbidity index,†† mean (SD)2.23 (2.06)2.25 (2.08)
Clinical Frailty scale,‡‡ no (%)
 Very fit23 (12.7)27 (14.9)
 Well70 (38.7)76 (42.0)
 Managing well73 (40.2)55 (30.4)
 Vulnerable10 (5.5)16 (8.8)
 Mildly frail3 (1.7)5 (2.8)
 Moderately frail1 (0.6)2 (1.1)
 Severely frail1 (0.6)0 (0.0)
Time from admission to randomisation (hours), median (IQR)8 (0–21)6 (0–22)
Time from symptoms onset to hospital admission (days), median (IQR)7 (4–9)6 (4–8)
  • *Data were not available for 25 patients (6.9% of study population).

  • †Chronic kidney disease was defined as severe in case of being on dialysis, status post kidney transplant, uraemia; moderate=creatinine >3 mg/dL (0.27 mmol/L). These definitions were reported according to the Charlson Comorbidity Index.

  • ‡Chronic liver disease was defined as severe in case of cirrhosis and portal hypertension with variceal bleeding history; moderate in case of cirrhosis and portal hypertension but no variceal bleeding history. These definitions were reported according to the Charlson Comorbidity Index.

  • §Cancer includes the following comorbid conditions as reported in the Charlson Comorbidity Index: localised solid tumour, metastatic solid tumour, lymphoma or multiple myeloma.

  • ¶Obesity was defined as a body mass index ≥30 kg/m2.

  • **The comorbidities were counted on the components of the Charlson Comorbidity Index, including obesity.

  • ††The Charlson Comorbidity Index consists of 17 items. Each item can be scored from 0 to 6 points and each has a different weight. The maximum Charlson comorbidity Index score (adjusted for age) is 37 points. The Charlson comorbidity Index includes the following comorbid conditions: acute myocardial infarction, congestive heart failure, peripheral vascular disease, cerebrovascular disease, dementia, chronic obstructive pulmonary disease, rheumatoid disease, peptic ulcer disease, mild and moderate/severe liver disease, diabetes mellitus with and without complications, hemiplegia/paraplegia, renal disease, cancer (any malignancy) and metastatic solid tumour, AIDS/HIV. The Charlson comorbidity Index provides a 10-year mortality risk based on weighted comorbid conditions, ranging from 0 (no comorbid conditions) to 29, with a score of 4 associated with an estimates 10-year survival of 53%.

  • ‡‡Degree of fitness and frailty (range, 1–9: 1, very fit; 5, mildly frail; 9, terminally ill).

  • BMI, body mass index; SpO2, peripheral oxygen saturation.