Table 2.
Subgroup analysis.
| Indicators of outcome | Subgroup classification | Number of studies | Heterogeneity test | Effect model | Meta | ||
|---|---|---|---|---|---|---|---|
| p | I 2 | MD (95% CI) | p | ||||
| 4–6 months' intervention, Hb at 6 months of age | Type of iron | ||||||
| Ferrous sulfate | 3 | p = 0.005 | 81% | R | 4.25 (−0.42, 8.92) | p = 0.07 | |
| Dextran iron | 1 | — | — | — | 12.71 (8.77, 16.65) | p < 0.001 | |
| Ethnicity | |||||||
| Afro-Asian | 2 | p < 0.001 | 95% | R | 6.34 (−6.12, 18.79) | p = 0.32 | |
| Europe and America | 2 | p = 0.11 | 61% | R | 6.33 (2.52, 10.15) | p = 0.001 | |
| Sample size | |||||||
| Large samples (n > 50) | 3 | p = 0.008 | 79% | R | 8.33 (3.84, 12.83) | p = 0.0003 | |
| Small samples (n ≤ 50) | 1 | — | — | — | 0.00 (−3.74, 3.74) | p > 0.999 | |
| Severity of iron deficiency | |||||||
| Countries with relative iron deficiency | 3 | p < 0.001 | 91% | R | 5.64 (−1.45, 12.73) | p = 0.12 | |
| Relatively iron-sufficient countries | 1 | — | — | — | 8.20 (5.03, 11.37) | p < 0.001 | |
|
| |||||||
| MCV | Ethnicity | ||||||
| Afro-Asian | 1 | — | — | — | 2.50 (1.03, 3.97) | p = 0.0009 | |
| Europe and America | 2 | p = 0.25 | 26% | F | 0.56 (−0.70, 1.82) | p = 0.38 | |
|
| |||||||
| Rate of weight gain | Ethnicity | ||||||
| Afro-Asian | 2 | p = 0.05 | 75% | R | 0.07 (−0.04, 0.18) | p = 0.24 | |
| Europe and America | 2 | p = 0.62 | 0 | F | −0.03 (−0.12, 0.07) | p = 0.61 | |