Comparison of Incidence of Severe Hyperbilirubinemia Between HFHSF Newborns and the Newman et al Study2

VariablesNewman et al StudyHFH:HFHSF GroupRelative Risk* (RR) After Controlling for Main Effect (Newman et al Study as Reference Group)
Total Newborns(n = 51 387)(%)Newborns With TSB ≥ 20 mg/dL(n = 1002)(%)Total Newborns(n = 3498)(%)Newborns With TSB ≥ 20 mg/dL(n = 21)(%)RR95% CI
Total cohort1002.01000.6
Gestational age in weeks0.260.17–0.44
Maternal race0.490.31–0.76
Maternal age in years0.330.21–0.50
Feeding type0.490.32–0.76
 Exclusive breastfeeding65.52.730.20.8
 Partial breastfeeding11.40.924.90.8
 Formula feeding23.10.445.00.2
  • The distribution of the two samples was significantly different in gestational age (P < .0001), gender (P = .018), maternal race (P < .0001), and maternal age (P < .0001).

  • * This is the overall relative risk of developing an age-specific TSB exceeding AAP criteria at HFHS versus the hospitals in the Newman et al study. Each variable was controlled for separately because cross-tabulation summary tables were not available. For example, after controlling for maternal race, the regression coefficient for the HFHSF group in the Poisson regression analysis is −0.722, indicating that the relative risk for developing severe hyperbilirubinemia is twofold lower in HFHSF newborns than in the Newman et al study (relative risk for the HFHSF group: Newman et al study = e−0.722 = 0.49).

  • Applied feeding distribution reported in a nested-case control study that used the same cohort for two different studies.12