Table 3.

Multivariate model analysis of possible predictors of POP.

	Final model (Model 6)†
Factors	B	SE	Wald	Adjusted HR	P value
Age	0.041	0.007	39.618	1.042	<0.001
WFNS grade	0.773	0.189	16.745	2.166	<0.001
Modified Fisher scale	0.278	0.078	12.615	1.320	<0.001
Endovascular treatment	-0.693	0.199	12.076	0.500	0.001
NLR	0.044	0.009	21.968	1.045	<0.001
WFNS × NLR	0.009	0.003	8.357	1.009	0.004

^∗Multivariate analysis: all variables in Table 1 having P < 0.05 were included in multivariate analysis. ^†Backward stepwise regression methods were used to produce the final model, in which process the least nonsignificant variable was removed from the model 1 at a time until all remaining variables had P < 0.05. POP: Post-operative pneumonia; NLR: Neutrophil to lymphocyte ratio; WFNS: World Federation of Neurosurgical Societies.