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. 2017 Sep 2;20(11):1359–1368. doi: 10.1093/ntr/ntx196

Table 3.

Estimated Results From Zero-Inflated Poisson (ZIP) Regression Models on Health Care Utilization by Types of Health Care Services, 2012–2015

Hospital nights (N = 129156) Emergency room visits (N = 128722) Doctor visits (N = 129210) Home care visits (N = 129287)
Logita Poissonb Logita Poissonb Logita Poissonb Logita Poissonb
Coef. p Coef. p Coef. p Coef. p Coef. p Coef. p Coef. p Coef. p
Tobacco use status
 Current ST users 0.28 .010 1.34 .336 0.41 .001 1.25 .043 0.34 .057 0.94 .580 −0.27 .465 1.10 .704
 Former ST users 0.30 .000 0.93 .490 0.39 .000 1.11 .057 0.14 .105 1.19 .008 0.13 .359 0.98 .884
 Non-ST tobacco users 0.29 .000 1.04 .535 0.32 .000 1.10 .003 0.15 .004 1.17 .000 0.07 .305 0.99 .905
 Never tobacco users Ref Ref Ref Ref
Gender
 Male −0.34 .000 1.32 .000 −0.25 .000 0.90 .004 −0.44 .000 0.92 .013 0.02 .830 1.05 .545
 Female Ref Ref Ref Ref
Age
 18–34 Ref Ref Ref Ref
 35–64 −0.15 .000 1.55 .000 −0.15 .000 1.01 .740 0.22 .000 1.22 .000 1.30 .000 1.38 .040
 65+ 0.40 .000 1.68 .000 0.13 .011 0.83 .001 0.91 .000 1.13 .035 2.51 .000 1.47 .016
Race/ethnicity
 NH white Ref Ref Ref Ref
 Hispanic −0.22 .000 0.96 .497 −0.22 .000 0.94 .177 −0.31 .000 0.99 .861 −0.19 .077 1.02 .830
 NH black 0.02 .578 1.15 .028 0.26 .000 1.11 .004 −0.12 .067 1.02 .761 0.24 .002 0.94 .328
 NH Asian −0.40 .000 0.99 .946 −0.43 .000 0.80 .011 −0.16 .175 0.74 .002 −0.70 .000 0.98 .931
 NH other 0.39 .002 1.08 .715 0.25 .024 1.29 .032 −0.06 .757 1.15 .351 0.31 .245 0.96 .764
Education
 Less than high school Ref Ref Ref Ref
 High school −0.13 .002 1.05 .538 −0.09 .038 0.89 .011 0.05 .464 0.93 .253 −0.35 .000 1.27 .001
 Some college −0.12 .005 1.02 .766 −0.06 .189 0.81 .000 0.15 .034 1.00 .986 −0.47 .000 1.00 .978
 College + −0.21 .000 0.89 .156 −0.26 .000 0.71 .000 0.20 .057 1.01 .883 −0.69 .000 1.21 .095
Poverty status
 Poor Ref Ref Ref Ref
 Low income −0.28 .000 0.88 .099 −0.20 .000 0.80 .000 −0.02 .790 0.84 .043 −0.43 .000 0.93 .327
 Middle income −0.54 .000 0.85 .090 −0.45 .000 0.65 .000 −0.20 .031 0.83 .042 −0.88 .000 1.02 .866
 High income −0.72 .000 0.69 .000 −0.46 .000 0.49 .000 −0.07 .531 0.76 .007 −1.32 .000 0.98 .857
 Unknown −0.49 .000 0.83 .064 −0.57 .000 0.83 .020 −0.34 .005 0.84 .088 −0.53 .000 1.14 .255
Marital status
 Married Ref Ref Ref Ref
 S/D/W 0.15 .000 1.11 .103 0.20 .000 1.04 .304 0.22 .000 1.00 .943 0.77 .000 1.23 .022
 Never married −0.48 .000 1.29 .012 0.03 .354 0.95 .222 −0.03 .522 1.02 .601 0.85 .000 1.53 .000
 Living with partner 0.13 .028 1.02 .881 0.31 .000 1.08 .194 0.04 .573 1.09 .226 0.35 .095 0.79 .164
Region
 Northeast Ref Ref Ref Ref
 Midwest −0.05 .272 1.08 .403 −0.07 .131 1.09 .056 −0.12 .102 1.00 .951 −0.32 .005 0.94 .522
 South −0.07 .067 0.92 .173 −0.10 .030 1.02 .545 0.11 .061 0.86 .002 −0.17 .118 1.02 .836
 West −0.20 .000 1.03 .731 −0.20 .000 1.08 .083 −0.12 .055 1.03 .574 −0.38 .003 1.29 .018
Binge drinking
 Yes 0.48 .000 1.24 .012 0.02 .502 1.05 .208 0.05 .366 1.14 .004 0.87 .000 1.14 .437
 No Ref Ref Ref Ref
BMI
 Underweight 0.17 .070 1.24 .062 0.00 .979 1.11 .183 0.11 .487 1.15 .226 0.75 .000 0.92 .551
 Normal Ref Ref Ref Ref
 Overweigh 0.10 .003 0.78 .000 0.08 .033 0.95 .230 0.11 .050 1.02 .641 −0.19 .016 0.91 .246
 Obese 0.28 .000 0.85 .010 0.23 .000 1.09 .036 0.31 .000 1.12 .010 0.06 .495 0.90 .158
Proportion of months uninsured −0.52 .000 0.87 .129 −0.22 .000 0.92 .027 −0.94 .000 0.93 .377 −1.54 .000 0.83 .298
Constant −2.02 .000 4.11 .000 −0.63 .000 2.23 .000 −0.78 .000 0.76 .006 −5.69 .000 2.77 .000

BMI = body mass index; NH = non-Hispanic; S/D/W = separated/divorced/widowed. Bold results indicate statistically significant results at the p < .05 level.

aFor the convenience of interpretation, the signs of the coefficients have been reversed so that the logit model reflects the probability of potentially having non-zero health care utilization.

bThe exponentiated coefficients are reported for Poisson models.