Table 4.

Cox proportional hazard regression model for predictors of index arterial line thrombosis.

Variables	Hazard ratio	95% Confidence interval	p value
Age
18–39 years	Ref	–	–
40–64 years	0.41	0.14–1.25	0.12
65+ years	1.19	0.28–5.08	0.81
Female	1.09	0.47–2.53	0.84
BMI
<30 kg/m2	Ref	–	–
≥30 kg/m2a	2.28	1.07–4.84	0.03
Smoker
Never smoker	Ref	–	–
Current smoker	1.01	0.26–3.90	0.99
Past smoker	0.71	0.21–2.42	0.58
Personal history of thrombosis	1.13	0.32–3.96	0.84
Diabetes	0.71	0.30–1.67	0.43
Malignancy	1.09	0.31–3.87	0.89
Surgery in 30d prior to ICU admission	6.98	0.69–70.9	0.10
SOFA scoreb	1.05	0.89–1.24	0.54
Number of arterial lines prior to index arterial line	1.18	0.64–2.19	0.59
Index arterial line located in radial artery	2.79	0.56–13.8	0.21
Systemic anticoagulation	0.61	0.27–1.38	0.23
Low dose heparin protocola	0.13	0.05–0.34	<0.001

Abbreviations: BMI = Body Mass Index; LDHS = low dose heparinized saline; Ref = Reference group; SOFA = Sequential Organ Failure Assessment.

^aStatistically significant at p < 0.05.

^bAt protocol start for post-LDHS patients and at index arterial line for pre-LDHS patients.