Table 4.

Propensity score based on indices of severity of illness to predict use of APRV in all patients (n=25)

Predictor	Odds ratio (95% CI)	P-value
APACHE II score	1.335 (0.801–2.224)	0.260
PaO2 to FiO2 ratio (on initiation of mechanical ventilation)	0.906 (0.776–1.059)	0.215
Maximum CRP (per mg/L increment)	1.082 (0.986–1.189)	0.097
Respiratory compliance (per ml/cm H2O increment) on initiation of mechanical ventilation	1.116 (0.882–1.412)	0.362
No. of quadrants with infiltrates on the CXR on admission to ICU	0.003 (0.001–19.82)	0.197
FiO2	0.870 (0.700–1.082)	0.210

The Hosmer-Lemeshow chi-square and Nagelkerke R² of the model were 0.820 (P=0.999) and 0.840, respectively. Median and interquartile range of propensity scores for ICU survivors were 0.09 and 0.01–0.91, respectively, and those for ICU non-survivors were 0.95 and 0.16–0.99.

APRV: airway pressure release ventilation; CI: confidence interval; APACHE: Acute Physiology and Chronic Health Evaluation; PaO₂: arterial oxygen partial pressure; FiO₂: fractional inspired oxygen; CRP: C-reactive protein; CXR, chest X-ray.