Table 3. Independent predictors of 90-day mortality by multivariate Cox regression analysis.

Variable	Hazard ratio (95% CI)	P value
Model 1
APACHE II score at ICU admission (per point)	1.11 (1.03–1.19)	<0.001
LDHday 1 (per 100 U/L)	1.43 (1.21–1.69)	<0.001
LDHc (per 10%)	1.31 (1.13–1.52)	<0.001
Model 2
APACHE II score at ICU admission (per point)	1.11 (1.03–1.19)	<0.01
LDHday 3 (per 100 U/L)	1.36 (1.17–1.57)	<0.001
LDHc (per 10%)	1.16 (1.00–1.34)	0.04

Model 1 adjusted for APACHE II score at ICU admission, LDH_{day 1}, LDHc, procalcitonin and platelet count at ICU admission. Model 2 adjusted for APACHE II score at ICU admission, LDH_{day 3}, LDHc, procalcitonin and platelet count at ICU admission (stepwise variable-selection method). As the APACHE II score have repeated items of PaO₂/FiO₂ ratio and white blood cell count, APACHE II score was entered into the multivariable analysis only. APACHE-II, Acute Physiology and Chronic Health Evaluation II; LDH_day1, LDH level at ICU admission (day 1); LDH_{day 3}, LDH level on day 3; LDHc, LDH change from day 1 to day 3 [calculated using the following formula: LDHc (%) = (LDH_{day 3} – LDH_{day 1})/LDH_{day 1} ×100%].