TABLE 3—

Full Model Including Interaction Effects Between Mother’s Race/Ethnicity and Family Income-to-Poverty Ratio: US National Immunization Survey, 2003

	Hazard Ratio (95% Confidence Interval)
Child’s race/ethnicity
Non-Hispanic other/multirace	0.98 (0.85, 1.13)
Non-Hispanic Black	0.63 (0.47, 0.84)***
Hispanic	0.97 (0.80, 1.18)
Non-Hispanic White (reference)	1.00
Income-to-poverty ratio
< 1	0.87 (0.74, 1.01)
1–1.99	0.93 (0.83, 1.05)
2–2.99	0.92 (0.83, 1.02)
≥ 3 (reference)	1.00
Interaction effectsa
Non-Hispanic other/multiracial × IPR < 1	0.89 (0.64, 1.25)
Non-Hispanic other/multiracial × IPR 1–1.99	1.11 (0.83, 1.49)
Non-Hispanic other/multiracial × IPR 2–2.99	0.95 (0.70, 1.30)
Non-Hispanic Black × IPR < 1	1.90 (1.32, 2.74)***
Non-Hispanic Black × IPR 1–1.99	1.48 (1.01, 2.19)*
Non-Hispanic Black × IPR 2–2.99	1.20 (0.75, 1.91)
Hispanic × IPR < 1	1.33 (1.02, 1.74)*
Hispanic × IPR 1–1.99	1.13 (0.88, 1.47)
Hispanic × IPR 2–2.99	1.13 (0.84, 1.52)

Note. IPR = income-to-poverty ratio. Model 7 included all variables used in the main effects model (model 6), but parameters are not shown here. A total of 9510 children completed the vaccination series.

^aInteraction terms between child’s race/ethnicity and IPR.

* P < .05; ***P < .001.