Table 2.

Results of metaanalysis for breastfeeding and RA risk.

ComparisonStudyCase, nSample Size, nNo. StudiesTest of AssociationModelHeterogeneityPublication Bias
OR (95% CI)ZpChi-squarepI2, %Begg TestEgger Test
Breastfeeding ever vs neverOverall1672143,67060.675 (0.493–0.924)2.450.014R13.020.02361.610.152
Breastfeeding ever vs neverWhite1017136,57250.741 (0.533–1.030)1.790.074R8.960.06255.40.8060.144
Breastfeeding 1–12 mos vs neverOverallNANA30.783 (0.641–0.957)2.390.017R0.0820.66400.2960.766
Breastfeeding > 12 mos vs neverOverallNANA30.579 (0.462–0.726)4.73<0.0005R1.40.496010.488
  • RA: rheumatoid arthritis; NA: not available; R: random effects.