Table 3. Results of Multivariate Poisson Regression Modeling of Medicaid Enrollment Gap Incidence on Caregiver and Child Characteristics, among the COHL Study Follow-up Cohort in North Carolina, during the Study Period (A) and Using all Available Medicaid History (B) between January 2004 and December 2010.

	Model Aa:			Model Ba:
	COHL study follow-up period			All available Medicaid history
	IRR	95% CI	p	IRR	95% CI	p
Health literacy (NVS)
Lowb	1.17	0.89–1.54	0.3	1.10	0.87–1.38	0.4
Moderate-Higherc	1.00	referent		1.00	referent
Race
White	1.00	referent		1.00	referent
African American	0.91	0.73–1.13	0.4	0.93	0.77–1.12	0.4
American Indian	0.86	0.64–1.15	0.3	0.94	0.75–1.18	0.6
Education (ordinal categorical)	1.10	0.96–1.26	0.2	1.08	0.96–1.21	0.2
Caregiver’s sex
Male	1.00	referent		1.00	referent
Female	0.53	0.35–0.80	0.003	0.62	0.43–0.90	0.01
Caregiver’s age (years; continuous)	0.98	0.96–1.00	0.01	0.98	0.96–0.99	<0.001
Child’s age (years; ordinal categorical)	0.93	0.86–1.02	0.1	0.99	0.93–1.06	0.9
Caregiver general health
Excellent/Very good/Good	0.83	0.61–1.12	0.2	0.88	0.69–1.14	0.3
Fair/Poor	1.00	referent		1.00	referent

Note. NVS = Newest Vital Sign; COHL = Carolina Oral Health Literacy; IRR = Incidence Rate Ratio; CI = Confidence Interval. The sample size was n = 1208.

^aVariable selection was based on a backward hierarchical procedure starting from a full model and a P<.2 criterion; caregivers’ race, age and general health were included a priori in the models; time at risk for a gap was considered time (months) of Medicaid enrollment.

^bDefined as NVS score: 0–1.

^cDefined as NVS score: 2–6.