Table 2.

Factors increasing the odds ratio of developing perioperative ion in lumbar spine fusion surgery.

	Odds Ratio	P Value
Male	2.53 (1.35–4.91)	0.005
Obesity	2.83 (1.52–5.39)	0.001
Wilson frame	4.30 (2.13–8.75)	< 0.001
Anesthesia duration, per hour	1.39 (1.22–1.58)	< 0.001
Estimated blood loss, per 1 L	1.34 (1.13–1.61)	0.001
Colloid as percent of non-blood replacement, per 5%	0.67 (0.52–0.82)	< 0.001

The risk factors were determined using a multivariable analysis in a case-control study. Details are in reference #(18).