Table 3.

Adjusted odds ratios for mean partial oxygen pressure (PaO₂) value and mean fraction of oxygen in inspired air (FiO₂) during ICU stay resulting from a multivariate regression analysis on data from the entire ICU stay

Covariate	Odds ratio	95% Confidence interval
Mean PaO2 in kPa:
< 8.9 (n = 402)	1.63	1.16 to 2.3
8.9 to 10.6 (n = 871)	1.51	1.18 to 1.96
10.6 to 12.6 (n = 970)	1.25	0.99 to 1.57
12.6 to 16.4 (reference category) (n = 841)	1
> 16.4 (n = 238)	1.04	0.64 to 1.68
Mean FiO2 (per 10%)	1.63	1.47 to 1.81

Odds ratio after adjustment for the following potential confounders: age, SAPS II, GCS score below 15, admission type, PaO₂/FiO₂ ratio at admission, and hospital. The equation of the eventual model is: Logit(p) = -7.060 + 0.090 × age (per 5 years) + 0.049 × SAPS II + 0.054 × I(GCS < 15) + 0.015 × I(admission type = urgent) + 0.161 × I(admission type = medical) + 0.004 × PaO₂/FiO₂ – 1.114 × I(hospital = 2) – 0.060 × I(hospital = 3) – 0.285 × I(hospital = 4) – 0.618 × I(hospital = 5) + 0.488 × mean FiO₂ (per 10%) + 0.492 × I(mean PaO₂ < 67) + 0.417 × I(67 ≤ PaO₂ < 80) + 0.221 × I(80 ≤ PaO₂ < 95) + 0.038 × I(PaO₂ ≥ 123). Probability of in-hospital death = e^(logit)/(1+e^(logit)).

GCS, Glasgow Coma Scale; ICU, intensive care unit; SAPS II, Simplified Acute Physiology Score II.