TABLE 3.

Hazard Ratio (HR) of Covariates in 5 Tested Cox Proportional Hazards Models Presented With r²

Model	1	2	3	4	5
	HR	HR	HR	HR	HR
Age			1.05**	1.05**	1.05**
Male gender			1.33*	1.29*	1.29*
Cervical fracture				1.21	1.66
Thoracic fracture				0.96	1.32
Lumbar fracture				0.97	1.33
Multilevel fractures					0.69
Sequential fractures					0.94
Surgical treatment	0.85	0.80*	0.82	0.79*	0.79*
Spinal cord injury		1.68**	1.57**	1.55**	1.55**
Charlson Comorbidity Index			1.27**	1.28**	1.28**
Year of admission			0.96**	0.96**	0.96**
r2	0.003	0.022	0.335	0.339	0.338
Degrees of freedom	1	2	6	9	11

Levels of significance: P < 0.1; ^*P < 0.05; ^**P < 0.001. HR indicates hazard ratio.