Table 2.
Means at baseline and week 22 with estimates of intervention effect for Hb, MCV, HCT, RDW-CV, serum ferritin, plasma zinc, and plasma retinol in the two study groups1.
| Baseline2 | Week 222 | Change from baseline to week 223 | Intervention effect4 | ||||
|---|---|---|---|---|---|---|---|
| n | Mean (SE) | n | Mean (SE) | Mean (95% CI) | Mean (95% CI) | p-value | |
| Hb, g/L | |||||||
| Placebo | 171 | 125.2 (1.9) | 153 | 133.3 (1.9) | 8.1 (4.7, 11.5) | 2.4 (-2.4, 7.2) | 0.333 |
| Intervention | 174 | 124.8 (1.9) | 153 | 135.3 (1.9) | 10.5 (7.1, 13.9) | ||
| MCV, fL | |||||||
| Placebo | 171 | 82.1 (0.4) | 153 | 81.1 (0.4) | − 1.0 (− 1.1, − 0.8) | 0.3 (0.1, 0.5) | 0.002 |
| Intervention | 174 | 82.2 (0.4) | 153 | 81.6 (0.4) | − 0.7 (− 0.8, − 0.5) | ||
| HCT, % | |||||||
| Placebo | 171 | 39.7 (0.4) | 153 | 38.6 (0.5) | − 1.1 (− 1.9, − 0.2) | 0.9 (− 0.2, 2.1) | 0.115 |
| Intervention | 174 | 39.6 (0.4) | 153 | 39.5 (0.5) | − 0.1 (− 0.9, 0.7) | ||
| RDW-CV, % | |||||||
| Placebo | 171 | 12.1 (0.1) | 153 | 11.9 (0.1) | − 0.2 (− 0.3, − 0.2) | 0.1 (− 0.0, 0.2) | 0.169 |
| Intervention | 174 | 12.0 (0.1) | 153 | 11.9 (0.1) | − 0.2 (− 0.2, − 0.1) | ||
| Serum ferritin, µg/L | |||||||
| Placebo | 168 | 67.1 (3.6) | 152 | 70.0 (3.6) | 2.8 (− 2.0, 7.6) | 9.1 (2.3, 15.9) | 0.009 |
| Intervention | 170 | 63.7 (3.6) | 150 | 75.6 (3.6) | 12.0 (7.1, 16.8) | ||
| Plasma zinc, µmol/L | |||||||
| Placebo | 170 | 10.9 (0.4) | 153 | 10.8 (0.4) | − 0.1 (− 0.4, 0.3) | 0.9 (0.4, 1.4) | < 0.001 |
| Intervention | 173 | 10.5 (0.4) | 151 | 11.3 (0.4) | 0.8 (0.5, 1.2) | ||
| Plasma retinol, µmol/L | |||||||
| Placebo | 169 | 1.1 (1.0) | 151 | 1.2 (1.0) | 1.05 (1.01, 1.10) | 1.15 (1.09, 1.21) | < 0.001 |
| Intervention | 172 | 1.1 (1.0) | 151 | 1.3 (1.0) | 1.21 (1.16, 1.26) | ||
1All estimates are from linear mixed models including group (intervention/placebo), time (baseline/week 22), and their interaction (group × time) as fixed effects, and school and child as random effects. The models for Hb, MCV, HCT, and RDW-CV were fitted on unadjusted data. The models for serum ferritin, plasma zinc, and plasma retinol used values adjusted for time of day of blood sampling (the zinc model only)42 and corrected for inflammation (all three models)40,41.
Hb haemoglobin, HCT haematocrit, MCV mean corpuscular volume, RDW-CV red blood cell distribution width.
2Values for Hb, MCV, HCT, RDW-CV, serum ferritin, and plasma zinc are mean (SE). Values for plasma retinol are geometric mean (geometric SE).
3Values for all outcomes except for plasma retinol are the mean change (95% CI) within each study group between baseline and week 22. Positive values indicate within-group increases. Values for plasma retinol are a ratio of geometric means (95% CI) for baseline and week 22—all ratios are above 1 and indicate within-group increases.
4The intervention effect for all outcomes except for plasma retinol is the difference in the change from baseline to week 22 between the intervention group and the placebo group (95% CI)—all values are positive and indicate greater positive changes in the intervention group. The intervention effect for plasma retinol is expressed as a ratio of ratios (95% CI)—the value is above 1 and indicates a positive change in the intervention group.