Table 4: Intersectional analyses for PTB multilevel models with interaction terms [OR (95% CI)].

Model 5: addition of race × income interactionsModel 6: addition of race × age interactionModel 7: addition of age × income interactionsModel 8: addition of race × income × age interactions

Intercept0.10 (0.10, 0.11)0.11 (0.10, 0.11)0.11 (0.10, 0.11)0.10 (0.10, 0.11)
African-American (AA)1.49 (1.29, 1.71)1.33 (1.17, 1.51)1.40 (1.23, 1.60)
White (referent group)
Low income 1.13 (0.98, 1.31)1.10 (0.95, 1.27)1.13 (0.99, 1.29)
Middle income 1.05 (0.92, 1.18)1.02 (0.90, 1.15)1.05 (0.93, 1.17)
High income (referent group)
AA × low income0.50 (0.33, 0.74)0.50 (0.35, 0.72)
AA × middle income0.59 (0.43, 0.82)0.61 (0.45, 0.89)
Age <170.97 (0.78, 1.21)1.14 (0.97, 1.36)0.94 (0.75, 1.19)
Age 17–19 (referent group)
AA status × Age <171.31 (1.00, 1.71)1.35 (0.98, 1.84)
Age <17 × low income1.01 (0.67, 1.53)1.15 (0.60, 2.20)
Age <17 × middle income1.00 (0.66, 1.49)1.15 (0.67, 1.97)
AA × Age <17 × low income0.81 (0.36, 1.83)
AA × Age <17 × middle income0.85 (0.40, 1.78)
Random variance
 Intercept (SD)0.03 (0.17)0.03 (0.18)0.03 (0.18)0.04 (0.19)
Statistics comparisons
 −2 log likelihood46230.6245036.946329.945120.22

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