Table 4.

Associations between preterm birth, neighborhood deprivation, and CRCT mathematics failure (interaction models).

	Unadjusted^a			Model I^b			Model II (fully adjusted)^c
	Additive	Multiplicative		Additive	Multiplicative		Additive	Multiplicative
Regression coefficients	β (95% CI)	β (95% CI)	RERI^d (95% CI)	β (95% CI)	β (95% CI)	RERI^d (95% CI)	β (95% CI)	β (95% CI)	RERI^d (95% CI)
Gestational age
Early preterm	0.181 (0.154, 0.208)	0.94 (0.85, 1.03)	0.14 (−0.07, 0.37)	0.159 (0.133, 0.185)	0.78 (0.69, 0.87)	−0.07 (−0.25, 0.11)	0.159 (0.133, 0.185)	0.77 (0.68, 0.87)	−0.14 (−0.29, 0.04)
Moderate preterm	0.071 (0.061, 0.080)	0.48 (0.42, 0.53)	0.01 (−0.09, 0.10)	0.054 (0.044, 0.063)	0.36 (0.31, 0.42)	−0.08 (−0.16, 0.00)	0.050 (0.041, 0.059)	0.34 (0.29, 0.39)	−0.09 (−0.17, 0.02)
Late preterm	0.023 (0.019, 0.028)	0.19 (0.16, 0.22)	0.01 (−0.04, 0.06)	0.015 (0.011, 0.019)	0.14 (0.11, 0.17)	−0.03 (−0.07, 0.01)	0.013 (0.009, 0.017)	0.12 (0.09, 0.15)	−0.03 (−0.07, 0.01)
Term	Ref	Ref		Ref	Ref		Ref	Ref
Neighborhood Deprivation Index (NDI)
1 unit increase in NDI	0.054 (0.051, 0.057)	0.36 (0.34, 0.39)		0.017 (0.015, 0.019)	0.11 (0.09, 0.13)		0.006 (0.001, 0.004)	0.04 (0.02, 0.06)
Interaction of Gestational age and NDI
Early preterm*NDI	0.029 (0.002, 0.056)	−0.16 (−0.23, −0.08)		0.043 (0.018, 0.069)	−0.09 (−0.17, −0.01)		0.048 (0.022, 0.073)	−0.09 (−0.17, −0.01)
Moderate preterm*NDI	0.004 (−0.007, 0.014)	−0.12 (−0.17, −0.07)		0.011 (0.002, 0.021)	−0.09 (−0.14, −0.03)		0.015 (0.006, 0.025)	−0.07 (−0.13, −0.02)
Late preterm*NDI	0.004 (−0.001, 0.009)	−0.05 (−0.08, −0.02)		0.007 (0.003, 0.011)	−0.04 (−0.07, −0.01)		0.008 (0.004, 0.011)	−0.03 (−0.06, 0.00)
p-value for interaction	0.057	<.0001		<.0001	<.001		<.0001	<.01

Estimated effect measures	RD (95% CI)	RR (95% CI)		RD (95% CI)	RR (95% CI)		RD (95% CI)	RR (95% CI)

Effect of preterm birth at low deprivation (NDI = −1)
Early preterm	0.152 (0.113, 0.191)	3.01 (2.62, 3.46)		0.116 (0.079, 0.152)	2.39 (2.08, 2.76)		0.111 (0.075, 0.147)	2.36 (2.03, 2.75)
Moderate preterm	0.067 (0.053, 0.080)	1.81 (1.67, 1.97)		0.042 (0.030, 0.055)	1.57 (1.44, 1.71)		0.035 (0.023, 0.047)	1.51 (1.38, 1.65)
Late preterm	0.019 (0.014, 0.024)	1.27 (1.21, 1.33)		0.008 (0.004, 0.012)	1.20 (1.14, 1.26)		0.005 (0.002, 0.008)	1.16 (1.10, 1.22)
Term	Ref	Ref		Ref	Ref		Ref	Ref
Effect of preterm birth at average deprivation (NDI = 0)
Early preterm	0.181 (0.154, 0.208)	2.57 (2.35, 2.81)		0.159 (0.133, 0.185)	2.19 (1.00, 2.40)		0.159 (0.133, 0.185)	2.17 (1.97, 2.38)
Moderate preterm	0.071 (0.061, 0.080)	1.61 (1.53, 1.70)		0.054 (0.044, 0.063)	1.44 (1.37, 1.52)		0.050 (0.041, 0.059)	1.40 (1.33, 1.48)
Late preterm	0.023 (0.019, 0.028)	1.21 (1.17, 1.24)		0.015 (0.011, 0.019)	1.15 (1.11, 1.18)		0.013 (0.009, 0.017)	1.13 (1.09, 1.16)
Term	Ref	Ref		Ref	Ref		Ref	Ref
Effect of preterm birth at high deprivation (NDI = 1)
Early preterm	0.210 (0.173, 0.247)	2.20 (2.01, 2.40)		0.202 (0.166, 0.239)	2.00 (1.83, 2.20)		0.206 (0.169, 0.243)	1.99 (1.81, 2.19)
Moderate preterm	0.075 (0.059, 0.090)	1.43 (1.35, 1.52)		0.065 (0.050, 0.080)	1.32 (1.24, 1.40)		0.065 (0.051, 0.080)	1.30 (1.23, 1.38)
Late preterm	0.027 (0.019, 0.035)	1.15 (1.10, 1.19)		0.022 (0.014, 0.029)	1.10 (1.06, 1.15)		0.020 (0.013, 0.027)	1.09 (1.05, 1.14)
Term	Ref	Ref		Ref	Ref		Ref	Ref

Note: All models clustered by census tract.

Unadjusted risk differences and risk ratios for each exposure.

Model I is adjusted for all covariates except maternal education.

Model II is fully adjusted.

Relative excess risk due to interaction between preterm birth and 1 SD increase in NDI (from 0 to 1), for each preterm birth category.