Table 4.

Univariate and multivariate Cox proportional hazards results for risk of death in 222 dogs with idiopathic IMHA for variables determined at time of first diagnosis with P < 0.20 and the variable "treatment protocol"

	Univariate analysis
Variablea	Hazard ratio	Nb	95% CI	Pc
Icterus	2.47	222	1.52 - 4	0.0003*
Urea (20 mmol/L)	2.22	168	1.55-3.19	0.0004*
Creatinine d (50 μmol/L)	1.28	160	1.15-1.42	0.0012*
Red cell osmotic fragility	0.426	181	0.221 - 0.819	0.018*
Thrombocytes (50 ×109/L)	0.902	205	0.821-0.991	0.0184*
Age (years)	1.09	221	1.01-1.17	0.0266*
APTTe (seconds)	1.03	135	1-1.05	0.0445*
Spherocytes	0.663	215	0.396 - 1.11	0.115
Hematocrit (L/L)	0.0173	222	0.00011 - 2.77	0.109
Treatment protocol	1.12	222	0.679-1.86	0.65
	Multivariate analysis
Urea (20 mmol/L)	2.56	164	1.729-3.789	0.0001*
Icterus	2.94	164	1.60 - 5.42	0.0005*
Spherocytes	0.38	164	0.2 - 0.72	0.0023*

^a Variables were entered in the Cox proportional hazards model either as a factor or as a continuous variable, in which case the hazard ratio was calculated for the interval that is given in the table.

^b Number of dogs is given in which the parameter was determined for which the Cox proportional hazards model calculated the hazard ratio.

^c P = P value

^d Plasma creatinine concentrations were corrected for body weight (van den Brom and Biewenga, 1981).

^e APPT = Activated partial thromboplastin time