Linear regression analyses using METs as the outcome variable
| Crude regression | Sex-adjusted regression | |||
| Coefficient (95% CI) | P value | Coefficient (95% CI) | P value | |
| Sex (female) | −3.12 (−5.14 to 1.11) | 0.0039 | – | – |
| Haemoglobin (g/L) | 0.074 (0.031 to 0.12) | 0.001 | 0.055 (0.01 to 0.10) | 0.024 |
| SaO2 (%) | 0.28 (0.008 to 0.55) | 0.044 | 0.29 (0.037 to 0.55) | 0.026 |
| CaO2* | 0.00073 (0.00037 to 0.0011) | 0.0002 | 0.00062 (0.0002 to 0.001) | 0.003 |
Normal quantile plots (online supplementary figure 3) supported the use of METs (‘1st‘ METs) as the dependent variable.
*CaO2 unit mL of oxygen/L.
CaO2, arterial oxygen content; METs, metabolic equivalents; SaO2, oxygen saturation.