Table 2.

Multivariable analysis assessing associations between respondent characteristics and transfusion thresholds in clinical practice^a

Clinical setting value	Predictors remaining in final model	Estimate (β)	P
WFNS grade 4 (day 3)	Specialty (neurosurgery)	0.46	0.003
WFNS grade 1 (day 3)	Transfusion protocol	-0.42	0.0008
	Transfusion protocolb Specialty (neurosurgery)c	0.88	<0.0001
TCD vasospasm (day 6)	Specialty (neurosurgery)	0.31	0.04d
DCI (day 7)	Multimodal neurological monitoring	0.32	0.04

^aMultivariable analysis was performed using generalized linear models with stepwise backward elimination of the least significant variable where P > 0.05. Initial models included country (United States vs. Canada), specialty (neurosurgery vs. critical care), multimodal monitoring (yes vs. no), use of a transfusion protocol (yes vs. no) and years in practice (continuous variable). All interactions were assessed, and those for which P < 0.05 in univariate analysis were incorporated into initial multivariable models. WFNS, World Federation of Neurological Surgeons scale; TCD, transcranial Doppler; DCI, delayed cerebral ischemia. ^bNeurosurgical specialty significantly modified practices among clinicians who use a protocol (see Results section for details); ^cYears in practice significantly modified practices among neurosurgeons (see Results section for details); ^dWhite's heteroscedasticity-specific standard error.