Table 2.

Factors associated with completion of the combined 7-vaccine series by age 24 months among children born in Montana 2015–2017, n=26,085^*

	Completion of the combined 7-vaccine series
Distance (miles) to nearest immunization provider	Unadjusted PR (95% CI)	Adjusted PR (95% CI)
Short (≤2 mi)	Reference	Reference
Medium (2.01–10 mi)	0.99 (0.96–1.03)	0.99 (0.95–1.02)
Long (>10 mi)	0.98 (0.96–1.00)	0.97 (0.96–0.99)
Sex*
Female	0.98 (0.96–1.00)	0.99 (0.97–1.00)
Male	Reference	Reference
Race and ethnicity
American Indian/Alaska Native, all ethnicities	0.90 (0.87–0.94)	0.92 (0.88–0.95)
Other known race/ethnicity	0.92 (0.87–0.97)	0.93 (0.88–0.97)
Missing race/ethnicity data	0.95 (0.93–0.97)	0.99 (0.97–1.01)
Non-Hispanic White	Reference	Reference
Categories based on rural-urban commuting area (RUCA) codes
Rural areas	0.88 (0.86–0.91)	0.88 (0.85–0.92)
Small towns	0.94 (0.92–0.97)	0.96 (0.92–1.00)
Micropolitan areas	0.98 (0.96–1.00)	0.98 (0.94–1.02)
Metropolitan areas	Reference	Reference
Availability of pediatric providers at clinics accessed
Only accessed clinics with pediatric providers	1.08 (1.05–1.11)	1.04 (1.01–1.07)
Sometimes accessed clinics with pediatric providers	1.21 (1.19–1.24)	1.19 (1.16–1.22)
Never accessed clinics with pediatric providers	Reference	Reference
Health Region
1	0.99 (0.95–1.04)	0.89 (0.84–0.94)
2	1.22 (1.19–1.26)	1.10 (1.06–1.15)
3	Reference	Reference
4	1.13 (1.10–1.16)	0.89 (0.86–0.93)
5	0.88 (0.86–0.91)	1.05 (1.01–1.09)
Tract-level neighborhood deprivation index (NDI)	0.99 (0.98–0.99)	0.99 (0.98–0.99)
County-level family medicine and pediatric provider density per 1,000 children ages 0–5 years
<10 providers	1.12 (1.07–1.18)	1.06 (1.01–1.11)
10–14.99 providers	1.06 (1.03–1.10)	0.91 (0.88–0.95)
15–19.99 providers	1.03 (0.99–1.07)	0.97 (0.93–1.01)
≥20 providers	Reference	Reference

^*Adjusting for year of birth as a random effect, with 234 observations excluded due to missing sex data