Prognostic indicators in colic horses 115 Fi g u r e 2 . Sensitivity/speciﬁcity curves and Receiver Operating Characteristic (ROC) curves for the ﬁnal lo- gistic model for medically treated cases and surgically treated cases. vivors and non-survivors according to diagno- sis and treatment are presented in Table 2. D-dimer values of the 20 controls of healthy horses all showed D-dimer values < 0.5 mmol/l. Univariable analysis of age, breed, gender and year of inclusion (1997 or 1999) did not show any statistical difference between survivors and non- survivors for either medically or surgically treated cases. Neither breed nor gender re- vealed any difference between surgical and medical cases. The median age was however lower (p= 0.035) in the surgically treated horses (6.5 and 8.0 years, respectively). The results of the univariable analysis of clini- cal and laboratory variables showing p-values <0.15 between survivors and non-survivors are given in Table 3. The univariable analysis of other blood param- eters as Mg, Na, total protein, albumin, arterial pH, arterial pO2 and pCO2, HCO3 and Standard Base Excess (SBE) all revealed p-values >0.15 for both medically and surgically treated cases. The univariable analysis of the clinical dichoto- mous variable intestinal reﬂux also showed a p- value >0.15 for both treatment groups. The de- gree of abdominal pain at the time of arrival to the hospital did not differ statistically between the survivors and non-survivors in the 2 treat- ment groups. As a result of a high correlation in the medically treated cases the variable haemoglobin (þ=0.99 to PCV) were excluded in the following logistic regression procedure. In the surgically treated cases the variables abdominal sounds, breath rate, CRT, PCV, haemoglobin and lactate were excluded due to high correlation to heart rate (heart rate/abdominal sounds þ=0,52, heart rate/ respiratory rate þ=0.53, heart rate/CRT þ=0.61, heart rate/PCV þ=0.67, heart rate/ HGB þ=0.63 and heart rate/lactate þ=0,59). The ﬁnal multiple logistic model included PCV as the only signiﬁcant predictor in medically Acta vet. scand. vol. 45 no. 1-2, 2004