Figure 2.

Effect of changes in Pao₂/Fio₂ ratio in the first 7 days on mortality and on the chance of being discharged alive from the intensive care unit (ICU) at the latest follow-up

Fio₂ = fraction of inspired oxygen; Pao₂ = arterial partial pressure of oxygen. Panel A shows the change in the Pao₂/Fio₂ ratio in the first 7 days of follow-up compared with the baseline value and according to survival at the latest follow-up. Panel B shows the change in the Pao₂/Fio₂ ratio in the first 7 days of follow-up compared with the baseline value and according to being discharged alive from the ICU at the latest follow-up. In both plots, circles are medians and the error bars represent the interquartile range (IQR); the P value represents the interaction between the groups and the days from an unadjusted mixed-effect quantile regression based on the asymmetric Laplace distribution for continuous variables and accounting for the repeated measurements. The median difference for the interaction is 4.19 (IQR, –2.10 to 10.50; P = 0.186) for the comparison of survivors and non-survivors, and 9.64 (IQR, 3.68–15.59; P = 0.002) for the comparison of being discharged alive or not. Panel C shows a marginal effect plot with the effect of changes in the Pao₂/Fio₂ ratio at Day 3 on the predicted risk of mortality at the longest follow-up from a univariable generalised linear model considering a binomial distribution. The odds ratio for the change is 0.99 (95% CI, 0.99–1.00; P = 0.441). Panel D shows a marginal effect plot with the effect of changes in the Pao₂/Fio₂ ratio at Day 3 on the predicted risk of being discharged alive from the ICU at the longest follow-up from a univariable generalised linear model considering a binomial distribution. The odds ratio for the change is 1.01 (95% CI, 0.99–1.02; P = 0.071).