TABLE 2.
Summary of All Food Color Results Grouped by A Priori Moderatorsa
| Effect Size |
Variability Across Studies |
||||||||
|---|---|---|---|---|---|---|---|---|---|
| Selection | Studies | N | G | 95% CI | P | Q | P | τ | I2 |
| Parent Report | |||||||||
| All | 20 | 794 | 0.18 | 0.08–0.29 | .0007 | 39.5 | <.01 | .15 | 52% |
| Two outliers removedb | 18 | 746 | 0.18 | 0.10–0.27 | .00003 | 21.7 | .19 | .08 | 22% |
| High-quality outcome | 11 | 619 | 0.13 | −0.00–0.25 | .053 | 24.3 | <.1 | .15 | 58% |
| Low-quality outcome | 9 | 175 | .29 | 0.11–0.46 | .002 | 12.0 | .15 | .15 | 33% |
| Blind validated | 5 | 504 | .14 | 0.05–0.22 | .002 | 0.7 | .95 | .00 | 0% |
| Blind not validated | 15 | 290 | .21 | 0.05–0.37 | .009 | 38.6 | .001 | .23 | 64% |
| Hyperactive only | 11 | 185 | .21 | −0.02–0.43 | .069 | 31.5 | .01 | .29 | 68% |
| Not purely hyperactive | 9 | 609 | .18 | 0.11–0.25 | .0001 | 6.4 | .59 | .00 | 0% |
| Diet responder only | 15 | 255 | .16 | 0.01–0.33 | .038 | 33.0 | <.01 | .21 | 57% |
| Not diet resp only | 5 | 539 | .20 | 0.07–0.32 | .001 | 6.8 | .18 | .08 | 36% |
| Colors only | 17 | 305 | .21 | 0.06–0.36 | .006 | 38.7 | <.01 | .22 | 59% |
| High quality | 8 | 130 | .13 | −0.12–0.37 | .307 | 23.6 | <.01 | .26 | 70% |
| FDA colors only | 13 | 243 | .13 | −0.04–0.30 | .128 | 25.6 | .01 | .21 | 53% |
| High quality | 6 | 85 | .00 | −0.25–0.04 | .167 | 4.9 | .43 | .00 | 0% |
| Teacher/Observer | |||||||||
| All | 10 | 323 | .07 | −0.03–0.18 | .146 | 6.0 | .73 | .00 | 0% |
| Teachers | 7 | 490 | .06 | −0.03–0.14 | .206 | 5.7 | .46 | .00 | 0% |
| Observers | 4 | 475 | .06 | −0.03–0.14 | .211 | 0.7 | .86 | .00 | 0% |
| Classroom | 8 | 280 | .08 | −0.03–0.19 | .160 | 5.3 | .62 | .00 | 0% |
| Clinic/laboratory | 3 | 53 | .03 | −0.17–0.24 | .750 | 1.9 | .39 | .00 | 0% |
| High quality | 8 | 288 | .10 | −0.01–0.21 | .086 | 5.5 | .60 | .00 | 0% |
| Colors only | 6 | 76 | .22 | 0.10–0.41 | .030 | 3.4 | .65 | .00 | 0% |
| FDA only | 5 | 50 | .12 | −0.01–0.35 | .290 | 0.5 | .96 | .00 | 0% |
| Attention Tests | |||||||||
| All | 6 | 154 | .27 | 0.07–0.47 | .007 | 6.4 | .27 | .12 | 22% |
| Colors onlyc | 5 | 68 | .34 | 0.06–0.62 | .017 | 5.4 | .24 | .16 | 30% |
| FDA only | 5 | 68 | .34 | 0.06–0.62 | .017 | 5.4 | .24 | .16 | 30% |
Note: CI = confidence interval.
Preselected, sample prescreened to be diet responsive prior to food color challenge; Food and Drug Administration (FDA) only, challenge exclusively includes US FDA–approved colors; other studies included FDA-approved colors in addition to other colors. For parent and teacher/observer analyses, time 1 to time 2 correlation is set as in methods; for psychometric tests of attention, it is set to 0.50. Sensitivity analyses indicated no change in results with correlations varied from 0.2 to 0.8.
Line 2 under parent studies: Two outliers removed are Adams17 and Goyette et al.,17 both with residual z > 1.96.
Sensitivity analysis with one study at a time removed showed that this effect survived removal of some studies but not others; details provided in Table S4, available online.