TABLE 2

Meta-analyses of the Relationship Between IPI and ASD

IPINo. of StudiesrefChildren, nChildren With ASD, n (%)Pooled Unadjusted OR (95% CI)I2, %Pooled Adjusted OR (95% CI)I2, %
Any ASD
 <12 mo528,30,3234205 0691533 (0.75)1.58 (1.02–2.45)941.90 (1.16–3.09)96
 12–23 mo528,30,3234343 5091693 (0.49)1.18 (0.84–1.66)921.27 (0.89–1.83)90
 24–35 mo528,30,3234219 940826 (0.38)0.94 (0.73–1.19)771.02 (0.80–1.29)68
 ≥36 moa528,30,3234233 634899 (0.38)1.00NA1.00NA
Any ASD
 <12 mo428,31,33,34169 8251855 (1.09)1.83 (1.33–2.54)93bb
 12–23 mo428,31,33,34255 5981913 (0.75)1.32 (1.09–1.59)80bb
 24–59 moa428,31,33,34278 5371619 (0.58)1.00NAbb
 ≥60428,31,33,3441 991665 (1.58)1.37 (1.02–1.86)83bb
Autistic disorder
 <12 mo328,30,34190 5461334 (0.70)1.96 (1.29–2.97)892.62 (1.53–4.50)c88
 12–23 mo328,30,34318 8881318 (0.41)1.25 (0.84–1.85)891.44 (0.84–2.47)c91
 24–35 mo328,30,34205 397602 (0.29)1.03 (0.81–1.30)611.14 (0.97–1.33)c0
 ≥36 moa328,30,34215 588563 (0.26)1.00NA1.00NA
Autistic disorder
 <12 mo228,34163 3831275 (0.78)2.19 (1.66–2.88)73bb
 12–23 mo228,34244 2521229 (0.50)1.51 (1.38–1.65)0bb
 24–59 moa228,34263 820884 (0.34)1.00NAbb
 ≥60 mo228,3435 488126 (0.36)1.15 (0.69–1.92)82bb
  • NA, not applicable; ref, reference number.

  • a Reference category.

  • b It was not possible to estimate pooled adjusted ORs and I2 tests because the reference categories did not coincide among the studies.

  • c Based on pooling of data from the studies by Cheslack-Postava et al28 and Gunnes et al.30