Table 3

Negative binomial regression results

	Individuals who are only covered by Medicare (N=1126) and individuals who are covered by Medicare and other health insurances (N=1462) in hospital stay				Individuals who are only covered by Medicare (N=3032) and individuals who are covered by Medicare and other health insurances (N=3307) in doctor’s visit
Visit times of last 2 years (visit ≥1)	Medicare only (group 1)		Medicare and other health insurances (group 2)		Medicare only (group 1)		Medicare and other health insurances (group 2)
	IRR	95% CI	IRR	95% CI	IRR	95% CI	IRR	95% CI
Region
New England and Mid Atlantic	Ref		Ref		Ref		Ref
EN Central and WN Central	0.902	0.756 to 1.076	0.797*	0.691 to 0.919	0.743*	0.668 to 0.826	0.884†	0.797 to 0.981
S Atlantic	1.047	0.886 to 1.236	0.903	0.784 to 1.039	0.847*	0.763 to 0.939	1.157*	1.043 to 1.283
ES Central and WS Central	1.058	0.882 to 1.270	0.740*	0.634 to 0.865	0.846*	0.755 to 0.947	0.997	0.893 to 1.115
Mountain and Pacific	0.882	0.728 to 1.069	0.726*	0.613 to 0.859	0.806*	0.722 to 0.900	1.140†	1.017 to 1.278
Age
<65	Ref		Ref		Ref		Ref
65–74	0.802†	0.672 to 0.957	0.757*	0.658 to 0.870	0.748*	0.665 to 0.840	0.719*	0.646 to 0.801
75–84	0.781*	0.658 to 0.927	0.663*	0.575 to 0.764	0.733*	0.651 to 0.824	0.686*	0.614 to 0.767
>85	0.785†	0.646 to 0.954	0.644*	0.545 to 0.761	0.717*	0.626 to 0.822	0.781*	0.686 to 0.890
Gender
Male	Ref		Ref		Ref		Ref
Female	1.111†	1.002 to 1.233	0.872*	0.793 to 0.957	1.002	0.940 to 1.068	1.043	0.977 to 1.113
Race
NH white	Ref		Ref		Ref		Ref
NH black	0.937	0.819 to 1.072	1.035	0.916 to 1.170	0.932	0.857 to 1.015	0.823*	0.754 to 0.898
Hispanic	1.066	0.898 to 1.265	1.066	0.893 to 1.272	1.011	0.904 to 1.129	0.929	0.817 to 1.057
Other	0.813	0.605 to 1.093	1.081	0.853 to 1.371	1.359*	1.135 to 1.628	1.172‡	0.974 to 1.410
Education
Less than high school education	Ref		Ref		Ref		Ref
High school/GED	0.824*	0.721 to 0.943	1.117	0.976 to 1.277	1.048	0.957 to 1.149	0.929	0.842 to 1.025
Undergraduate	0.859	0.724 to 1.020	0.914	0.773 to 1.081	1.174*	1.052 to 1.310	0.933	0.830 to 1.048
Graduate	0.873	0.689 to 1.107	0.934	0.750 to 1.162	1.230*	1.073 to 1.411	1.208*	1.054 to 1.385
Chronic disease
No chronic disease	Ref		Ref		Ref		Ref
Only one chronic disease	0.829	0.549 to 1.252	0.983	0.671 to 1.440	1.712*	1.450 to 2.021	1.467*	1.243 to 1.731
More than one chronic disease	1.109	0.760 to 1.619	1.261	0.884 to 1.799	2.261*	1.941 to 2.634	2.262*	1.939 to 2.639
Employment status
Full-time	Ref		Ref		Ref		Ref
Part-time	0.865	0.607 to 1.232	1.115	0.801 to 1.550	1.132	0.942 to 1.360	1.092	0.907 to 1.316
Unemployed	1.002	0.679 to 1.478	1.310	0.942 to 1.820	1.706*	1.363 to 2.135	1.351*	1.090 to 1.674
Retired	1.147	0.841 to 1.564	1.562*	1.185 to 2.058	1.358*	1.152 to	1.283*	1.089 to 1.513
Household income
Lower income	Ref		Ref		Ref		Ref
Middle income	0.911	0.702 to 1.181	1.042	0.862 to 1.260	1.133‡	0.997 to	0.951	0.847 to 1.068
Upper income	0.892	0.702 to 1.133	0.941	0.764 to 1.159	0.974	0.859 to	0.931	0.822 to 1.054

We show ORs and 95% CI here. Counts do not sum to 4098 or 4651 due to missing values for some of the independent variables.
*Significant at 1% level (two-tailed test).
†Significant at 5% level (two-tailed test).
‡Significant at 10% level (two-tailed test).
EN, East North; ES, East South; GED, General Educational Development; NH, non-Hispanic; S, South; WN, West North; WS, West South.