Baseline characteristics of the patients in the case and control groups
| Early group (controls) n=103 | Late group (cases) n=103 | |
| CPAP (count) | 3 (1 survived and two died) | 15 (8 survived and seven died) |
| Mean A-a gradient at the start of CPAP | 40.89 | 40.83 |
| Mean A-a gradient at the end of CPAP | 33.90 | 31.94 |
| Mean A-a difference start/end | 19.53 | 7.03 |
| Median O2 for CPAP patients (kPa) | NA | 9.4 |
| Median CO2 for CPAP patients (kPa) | NA | 4.8 |
| Median FiO2 for CPAP patients | NA | 56.5 |
| Intubated (count) | 15 | 7 |
| Average stay in hospital (until discharged) (days)* | 8 | 12 |
| Mean time in hospital until death (days) | 9.2 | 7 |
| Average age (years) | 70.5 | 70.3 |
| Average age at death (years) | 74.9 | 76.1 |
| Sex (count) | 66 M / 37F | 66 M / 37F |
| Deaths (count) | 41 (34M/7F) | 46 (35M/11F) |
| From care homes (count) | 21 | 39 |
| Diabetic (count) | 23 | 35 |
| Pulmonary (count) | 35 | 22 |
| With asthma | 14 | 10 |
| With emphysema | 20 | 9 |
| With bronchiectasis | 3 | 5 |
| Cardiac (count) | 36 | 27 |
| Renal (count) | 10 | 7 |
| Hypertension (count) | 36 | 36 |
| Average no of comorbidities per patient | 1.37 | 1.23 |
A-A stands for alveolar–arterial gradient a measure of gas/exchange diffusion. Values of O2, CO2 and FiO2 for early group not reported since they were available for only one patient.
*Since confirmation of COVID-19.
CPAP, continuous positive air pressure; Fio2, fractional inspired oxygen; ICU, Intensive Care Unit; NA, not available.