Table 2: Factors Contributing to DVT/PE in the aggregated group of all patients. For the two level factors, the value in the second and third columns is the fraction of patients without and with DVT/PE who had that factor. NS indicates a p value of >0.1 in all statistical tests used. For the 2x2 tables the first p value is from the χ² statistic and the second is from the 2-way Fisher’s Exact Test. For the other data the first p value is that for the t-test and the second for the Mann-Whitney U test (two-tailed).

Factor	No DVT	DVT	Statistic	p*	Relative Risk for DVT/PE	95% Confidence Interval
Length of Stay (days)	8.6 (14)	22.8 (20)	t(2434)=-5.2	p<.0001 (<0.001)
Age (years)	71.3 (16)	70.7 (18)	t(2500)=0.21	NS
Race	--	--	χ2=1.7 df=6	NS
Gender	56% female	52% female	χ2=0.25	NS	1.08 female	0.78-1.5 female
Height (inches)	65.9 (6.2)	66.6 (3)	t(2460)=-0.64	NS
Weight (pounds)	167 (45)	182 (66)	t(2471)=-1.85	p=0.06 (0.5)
BMI	27 (6)	28 (9)	t(2456)=-0.14	NS
Afib/Flutter	0.18	0.21	χ2=0.28	NS	1.25	0.54-2.9
Heart Failure	0.06	0.15	χ2=4.22	p=0.04 (0.06)	2.65	1.01-7.0
Prior TIA	0.13	0.1	χ2=0.45	NS	2.2	0.2-2.2
CAD/MI	0.23	0.24	χ2=0.01	NS	1.05	0.47-2.7
Diabetes	0.25	0.24	χ2=0.02	NS	0.95	0.43-2.1
Hypertension	0.69	0.73	χ2=0.19	NS	1.2	0.55-2.6
Peripheral Vascular Disease	0.02	0.0	χ2=0.70	NS	0.987	0.98-0.991
Smoking	0.09	0.06	χ2=0.37	NS	0.64	0.15-2.7
Carotid Stenosis	0.02	0.00	χ2=0.75	NS	0.987	0.98-0.991
Prior CVA	0.15	0.21	χ2=1.6	NS	1.7	0.7-4.0
Prosthetic Heart Valve	0.025	0.03	χ2=0.04	NS	1.2	0.16-9.0
Initial NIHSS	5.8 (6.5)	11.4 (6)	t(1145)=-2.84	p=0.0046 (0.002)
Discharge NIHSS	2.8 (5)	9.8 (9.8)	t(853)=-2.8	p=0.005 (0.07)
Weakness	0.42	0.27	χ2=3.01	p=0.08 (0.11)	0.5	0.2-1.1
Altered LOC	0.14	0.30	χ2=7.13	p=0.0076 (0.02)	2.7	1.3-5.7
Aphasia	0.27	0.24	χ2=0.12	NS	0.87	1.9
Ambulatory by Day 2	0.254	0.1	χ2=4.6	p=0.03 (0.04)	0.29	0.09-0.96
Heparin or LMWH	0.44	0.36	χ2=0.74	NS	0.73	0.36-1.5
Serial Compression Devices	0.37	0.33	χ2=0.65	NS	0.73	0.34-1.6
Warfarin	0.026	0.03	χ2=0.02	NS	1.2	0.16-8.6
Hyperlipidemia	0.33	0.36	χ2=0.2	NS	1.18	0.52-2.4