Table 2. Univariate and multivariate analysis of demographic and clinical factors of unstable angina patients associated with ≥2 days length of inpatient stay.

Variables/characteristics	Univariate analysis			Multivariate analysis
	OR (95% CI)	P value		OR (95% CI)	P value
Age
<65 years	Reference			Reference
≥65 years	1.48 (1.45–1.51)	<0.0001		1.29 (1.24–1.34)	<0.0001
Gender
Men	Reference			Reference
Women	1.39 (1.36–1.42)	<0.0001		1.24 (1.20–1.27)	<0.0001
Race/ethnicity
Asian or Pacific islander	Reference			Reference
White	0.87 (0.80–0.95)	0.0011		0.85 (0.78–0.93)	0.0006
African-American	1.44 (1.32–1.57)	<0.0001		1.28 (1.16–1.40)	<0.0001
Hispanics	1.28 (1.17–1.40)	<0.0001		1.21 (1.10–1.33)	<0.0001
Native American	0.75 (0.63–0.90)	0.0016		0.78 (0.65–0.95)	0.0107
Others	0.90 (0.81–1.00)	0.0600		0.83 (0.74–0.93)	0.0014
Co-morbid conditions
Obesity	1.15 (1.11–1.19)	<0.0001		1.14 (1.10–1.19)	<0.0001
Hypertension	1.22 (1.19–1.25)	<0.0001		1.03 (1.00–1.06)	0.0765
Diabetes mellitus without complications	1.26 (1.23–1.29)	<0.0001		1.15 (1.11–1.18)	<0.0001
Diabetes mellitus with complications	1.93 (1.81–2.05)	<0.0001		1.52 (1.41–1.64)	<0.0001
Congestive heart failure	13.75 (7.64–24.80)	<0.0001		6.29 (3.11–12.72)	<0.0001
Peripheral vascular disease	1.55 (1.48–1.63)	<0.0001		1.22 (1.15–1.30)	<0.0001
Renal failure	2.07 (1.97–2.17)	<0.0001		1.26 (1.19–1.34)	<0.0001
Coagulopathy	2.22 (1.99–2.47)	<0.0001		1.68 (1.48–1.91)	<0.0001
Chronic lung disease	1.42 (1.38–1.46)	<0.0001		1.33 (1.29–1.38)	<0.0001
Alcohol abuse	1.072 (1.00–1.15)	0.0500		1.21 (1.11–1.32)	<0.0001
Nicotine dependence	0.78 (0.77–0.80)	<0.0001		0.83 (0.80–0.85)	<0.0001
Tumor present	1.34 (1.22–1.46)	<0.0001		1.25 (1.12–1.39)	<0.0001
Metastatic disease	1.99 (1.63–2.42)	<0.0001		1.62 (1.29–2.04)	<0.0001
Deficiency anemias	2.34 (2.24–2.45)	<0.0001		1.54 (1.45–1.62)	<0.0001
Lymphoma	1.52 (1.25–1.90)	<0.0001		1.27 (1.00–1.61)	0.0462
Weight loss	2.71 (2.24–3.28)	<0.0001		1.70 (1.36–2.13)	<0.0001
Depression	1.20 (1.15–1.25)	<0.0001		1.19 (1.13–1.25)	<0.0001
Hypothyroidism	1.19 (1.15–1.24)	<0.0001		1.05 (1.00–1.09)	0.0584
Liver disease	1.44 (1.29–1.60)	<0.0001		1.32 (1.16–1.50)	<0.0001
Electrolyte disturbances	1.80 (1.72–1.88)	<0.0001		1.41 (1.34–1.49)	<0.0001
Ulcer disease without bleeding	1.54 (1.26–1.89)	<0.0001		1.63 (1.27–2.09)	0.0001
In-hospital complications
Myocardial infarction	1.30 (1.16–1.45)	<0.0001		1.17 (1.02–1.34)	0.0284
Acute kidney injury	3.51 (3.16–3.90)	<0.0001		1.83 (1.62–2.06)	<0.0001
Deep vein thrombosis	2.99 (2.15–4.15)	<0.0001		2.19 (1.52–3.16)	<0.0001
Sepsis	5.706 (3.48–9.36)	<0.0001		2.05 (1.16–3.62)	0.014
Pneumonia	4.90 (2.19–10.92)	<0.0001		2.71 (1.15–6.40)	0.0233
Stroke	3.04 (2.52–3.66)	<0.0001		2.64 (2.12–3.30)	<0.0001
Cardiogenic shock	1.23 (0.85–1.78)	0.28		0.60 (0.36–0.98)	0.0416
Urinary tract infection	2.96 (2.72–3.21)	<0.0001		2.12 (1.92–2.34)	<0.0001
Blood loss	3.47 (2.76–4.35)	<0.0001		1.95 (1.47–2.59)	<0.0001
In-hospital procedures
Cardiac catheterization	1.85 (1.80–1.91)	<0.0001		1.86 (1.79–1.93)	<0.0001
Percutaneous transluminal coronary angioplasty	1.67 (1.57–1.78)	<0.0001		1.24 (1.14–1.34)	<0.0001
Transfusion	6.43 (5.58–7.42)	<0.0001		3.06 (2.57–3.64)	<0.0001
Coronary artery bypass graft	197.66 (64.30–607.70)	<0.0001		161.24 (39.57–657.04)	<0.0001
Intubated	1.73 (1.40–2.14)	<0.0001		0.64 (0.48–0.85)	0.002
Insurance status
Private insurance	Reference			Reference
Medicare	1.72 (1.67–1.76)	<0.0001		1.29 (1.24–1.34)	<0.0001
Medicaid	1.73 (1.66–1.80)	<0.0001		1.40 (1.33–1.47)	<0.0001
Workers compensation	1.15 (1.10–1.21)	<0.0001		1.13 (1.07–1.20)	<0.0001
Self-pay	2.00 (1.68–2.28)	<0.0001		1.69 (1.43–2.00)	<0.0001
Other	1.30 (1.22–1.38)	<0.0001		1.30 (1.21–1.41)	<0.0001
Hospital regions
West	Reference			Reference
Northeast	1.22 (1.18–1.26)	<0.0001		1.32 (1.27–1.38)	0.1619
Midwest	1.12 (1.09–1.16)	<0.0001		1.04 (0.99–1.09)	<0.0001
South	1.23 (1.19–1.27)	<0.0001		1.26 (1.21–1.31)	<0.0001
Hospital teaching status/ location
Rural	Reference			Reference
Urban non-teaching	1.32 (1.28–1.35)	<0.0001		1.25 (1.20–1.29)	<0.0001
Urban teaching	1.62 (1.57–1.67)	<0.0001		1.27 (1.22–1.32)	<0.0001
Hospital bed size
Small	Reference			Reference
Medium	1.23 (1.19–1.27)	<0.0001		1.12 (1.08–1.16)	<0.0001
Large	1.43 (1.39–1.48)	<0.0001		1.28 (1.24–1.33)	<0.0001
Admitted on
Weekday	Reference			Reference
Weekend	1.63 (1.59–1.67)	<0.0001		1.74 (1.69–1.80)	<0.0001
Admission type
Non-elective	Reference			Reference
Elective	1.15 (1.10–1.20)	<0.0001		1.15 (1.09–1.22)	<0.0001