Table 3:

Results of univariable and multivariable hierarchical logistic regression models for all-cause 30-day readmission

Covariates	Unadjusted OR (95% CI)	p-value	Adjusted OR (95% CI)*	p-value
Age<65 years	1.02 (1.00–1.05)	0.10	1.21 (1.17–1.25)	<0.001
Female sex	1.10 (1.07–1.13)	<0.001	1.09 (1.07–1.12)	<0.001
Primary payer
Medicare	Reference		Reference
Medicaid	1.15 (1.11–1.20)	<0.001	1.05 (1.002–1.10)	0.04
Private insurance	0.54 (0.52–0.56)	<0.001	0.63 (0.60–0.66)	<0.001
Self-pay	0.51 (0.48–0.55)	<0.001	0.61 (0.57–0.66)	<0.001
No charge	0.50 (0.42–0.59)	<0.001	0.61 (0.51–0.72)	<0.001
Other	0.66 (0.60–0.72)	<0.001	0.71 (0.65–0.78)	<0.001
Missing	0.53 (0.35–0.81)	<0.001	0.57 (0.37–0.86)	0.008
Income quartile of patient’s ZIP code
First	Reference		Reference
Second	0.92 (0.89–0.95)	<0.001	0.97 (0.94–1.00)	0.06
Third	0.88 (0.85–0.91)	<0.001	0.95 (0.91–0.99)	0.007
Fourth	0.83 (0.79–0.87)	<0.001	0.93 (0.89–0.97)	0.002
Missing	0.87 (0.78–0.97)	0.01	0.94 (0.84–1.04)	0.23
Hospital characteristics
Hospital bedsize
Small	Reference		Reference
Medium	1.09 (1.02 – 1.15)	0.007	1.05 (0.99–1.11)	0.08
Large	1.11 (1.05–1.17)	<0.001	1.07 (1.01–1.12)	0.02
Teaching status
Metropolitan nonteaching	Reference		Reference
Metropolitan teaching	0.97 (0.93–1.00)	0.07	0.98 (0.95–1.02)	0.36
Nonmetropolitan hospital	0.89 (0.84–0.95)	<0.001	0.94 (0.88–1.00)	0.054
Hospital control
Government, nonfederal	Reference		Reference
Private, not-for-profit	1.04 (0.98–1.10)	0.19	1.01 (0.96–1.06)	0.78
Private, investor-owned	1.14 (1.07–1.22)	<0.001	1.10 (1.03–1.16)	0.003
Comorbidities
DM with complications	1.64 (1.59–1.70)	<0.001	1.20 (1.16–1.24)	<0.001
Chronic kidney disease	1.85 (1.81–1.90)	<0.001	1.20 (1.16–1.24)	<0.001
End-stage renal disease	2.21 (2.14–2.29)	<0.001	1.46 (1.41–1.52)	<0.001
Valvular heart disease	1.11 (1.05–1.16)	<0.001	1.03 (0.98–1.09)	0.29
Obesity	0.89 (0.86–0.91)	<0.001	0.86 (0.83–0.89)	<0.001
Peripheral vascular disease	1.28 (1.24–1.33)	<0.001	1.10 (1.06–1.15)	<0.001
Chronic lung disease	1.44 (1.40–1.48)	<0.001	1.19 (1.16–1.23)	<0.001
Pulmonary circulation disease	1.37 (1.30–1.45)	<0.001	1.09 (1.03–1.16)	0.003
Chronic liver disease	1.63 (1.52–1.75)	<0.001	1.27 (1.18–1.37)	<0.001
Coagulopathy	1.24 (1.18–1.31)	<0.001	1.02 (0.97–1.08)	0.41
Drug abuse	1.37 (1.30–1.44)	<0.001	1.32 (1.25–1.40)	<0.001
Charlson comorbidity index >3	1.93 (1.88–1.98)	<0.001	1.25 (1.21–1.29)	<0.001
End-organ involvement
Acute or unspecified heart failure	1.92 (1.87–1.98)	<0.001	1.37 (1.32–1.42)	<0.001
Acute myocardial infarction	0.95 (0.91–0.98)	0.004	1.00 (0.96–1.04)	0.87
Stroke or transient ischemic attack	0.54 (0.52–0.56)	<0.001	0.76 (0.73–0.80)	<0.001
Length of stay > median	1.44 (1.40–1.47)	<0.001	1.25 (1.22–1.29)	<0.001
Disposition
Routine	Reference		Reference
Transfer to short-term hospital	1.48 (1.33–1.64)	<0.001	1.60 (1.44–1.78)	<0.001
Transfer to skilled nursing facility or intermediate care facility	1.35 (1.31–1.39)	<0.001	1.29 (1.24–1.33)	<0.001
Home healthcare	1.36 (1.32–1.41)	<0.001	1.24 (1.20–1.28)	<0.001
Discharge against medical advice	2.44 (2.24–2.66)	<0.001	2.20 (2.01–2.40)	<0.001
Unknown	0.31 (0.16–0.61)	<0.001	0.34 (0.17–0.68)	0.002

*AIC for full model – AIC for null model= –7404.3, BIC for full model – BIC for null model= –7013.5. Differences in AIC and BIC for full model versus null model indicate very strong support for the full model. Likelihood ratio test showed a statistically significant improvement in model fit (p<0.001) for the full model compared with the null model.

AIC: Akaike Information Criterion, BIC: Bayesian Information Criterion