Table 2.
Distribution of iron status and anemia by study cohort
| Kenya | Uganda | Burkina Faso | South Africa | The Gambia | Pooled* | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Category | n/total | % | 95% CI | n/total | % | 95% CI | n/total | % | 95% CI | n/total | % | 95% CI | n/total | % | 95% CI | n/total | % | 95% CI |
| Iron deficiency† | 499/1408 | 35.4 | 32.9, 37.9 | 438/1267 | 34.6 | 31.9, 37.2 | 115/324 | 35.5 | 30.3, 40.7 | 375/894 | 41.9 | 38.7, 45.2 | 163/752 | 21.7 | 18.7, 24.6 | 1590/4645 | 34.2 | 32.9, 35.6 |
| Anemia‡ | 609/870 | 70.0 | 66.9, 73.1 | 652/1312 | 49.7 | 47.0, 52.4 | 288/331 | 87.0 | 83.4, 90.6 | n/a | n/a | n/a | 448/746 | 60.1 | 56.5, 63.6 | 1997/3259 | 61.3 | 59.6, 62.9 |
| Iron deficiency anemia§ | 207/833 | 24.8 | 21.9, 27.8 | 255/1209 | 21.1 | 18.8, 19.8 | 96/309 | 31.1 | 25.9, 36.3 | n/a | n/a | n/a | 123/745 | 16.5 | 13.8, 19.2 | 681/3096 | 22.0 | 20.5, 23.5 |
| Biomarker | n | Mean | 95% CI | n | Mean | 95% CI | n | Mean | 95% CI | n | Mean | 95% CI | n | Mean | 95% CI | n | Mean | 95% CI |
| Hemoglobin, g/dL | 870 | 10.2 | 10.1, 10.3 | 1312 | 9.1 | 9.0, 9.2 | 331 | 9.6 | 9.4, 9.7 | n/a | n/a | n/a | 746 | 10.7 | 10.6, 10.8 | 3259 | 10.5 | 10.5, 10.6 |
| Ferritin, μg/L | 1408 | 21.8 | 20.6, 23.1 | 1267 | 20.8 | 19.6, 22.0 | 324 | 22.2 | 19.7, 24.9 | 894 | 14.9 | 14.0, 15.9 | 752 | 25.1 | 23.6, 26.8 | 4645 | 20.5 | 19.9, 21.1 |
| sTfR, mg/L | 1467 | 17.9 | 17.5, 18.3 | 1343 | 6.7 | 6.5, 7.0 | 342 | 17.7 | 16.7, 18.7 | 893 | 11.2 | 10.9, 11.5 | 661 | 3.4 | 3.4, 3.5 | 4045 | 11.7 | 11.4, 11.9 |
| Hepcidin, μg/L | 1373 | 5.8 | 5.4, 6.2 | 1333 | 6.8 | 6.4, 7.2 | 309 | 5.3 | 4.6, 6.3 | 878 | 7.7 | 7.1, 8.4 | 709 | 6.0 | 5.3, 6.7 | 4602 | 6.4 | 6.2, 6.6 |
| BIS, mg/kg** | 1393 | −0.8 | −1.0, −0.5 | 1241 | 2.5 | 2.2, 2.8 | 322 | −0.6 | −1.1, −0.1 | 893 | −0.4 | −0.7, −0.2 | 660 | 5.7 | 5.4, 6.0 | 3849 | 0.4 | 0.2, 0.5 |
| Ferritin index†† | 1389 | 14.4 | 13.9, 14.9 | 1234 | 5.5 | 5.3, 5.8 | 322 | 13.9 | 12.8, 15.1 | 881 | 10.1 | 9.7, 10.6 | 660 | 2.6 | 2.5, 2.7 | 3826 | 9.7 | 9.5, 10.0 |
| Serum iron, μmol/L | 1428 | 6.5 | 6.3, 6.7 | n/a | n/a | n/a | 337 | 6.0 | 5.7, 6.4 | n/a | n/a | n/a | 737 | 8.6 | 8.3, 8.9 | 1765 | 6.4 | 6.2, 6.6 |
| Transferrin, g/L | 1409 | 2.8 | 2.7, 2.8 | 1333 | 2.8 | 2.6, 2.7 | 327 | 2.7 | 2.6, 2.8 | 894 | 2.7 | 2.7, 2.8 | n/a | n/a | n/a | 3963 | 2.8 | 2.7, 2.8 |
| TSAT, %‡‡ | 1386 | 9.4 | 9.0, 9.8 | n/a | n/a | n/a | 325 | 8.9 | 8.3, 9.7 | n/a | n/a | n/a | 734 | 12.8 | 12.3, 13.3 | 1711 | 9.3 | 9.0, 9.6 |
| ZPP, μmol/mol heme | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a | n/a | 751 | 85.9 | 82.4, 89.5 | 751 | 85.9 | 82.4, 89.5 |
| MCV, fL | 499 | 65.7 | 65.0, 66.5 | 1305 | 71.0 | 70.6, 71.5 | n/a | n/a | n/a | n/a | n/a | n/a | 741 | 75.6 | 75.1, 76.1 | 2545 | 71.2 | 70.9, 71.6 |
n/a not available, BIS body iron store, sTfR soluble transferrin receptors, TSAT transferrin saturation, ZPP zinc protoporphyrin, MCV mean corpuscular volume
The mean values are geometric means except for BIS, transferrin, hemoglobin, and MCV which are arithmetic means
*Pooled values for sTfR, BIS, ferritin index, iron, transferrin, and TSAT, exclude The Gambia since markers were measured using different assays compared to the other cohorts
†Iron deficiency defined using the WHO definition as ferritin < 12 μg/L or < 30 μg/L in presence of inflammation (C-reactive protein> 5 mg/L or α1-antichymotrypsin > 0.6 g/dL) in children < 5 years or < 15 μg/L in children ≥ 5 years [8]
‡Anemia was defined as hemoglobin < 11 g/dL in children aged 0 to 5 years or hemoglobin < 11.5 g/dL in children above 5 years [27]. Hemoglobin measurements unavailable in South Africa
§Iron deficiency anemia defined as iron deficiency and anemia [27]
**Body iron store was calculated using the ratio of soluble transferrin receptors and ferritin concentrations, −(log10((sTfR × 1000)/ferritin) − 2.8229)/0.1207 [24]
††Ferritin index was defined as sTfR/log10 ferritin [25]
‡‡TSAT was calculated as ((iron (μmol/L)/transferrin (g/L) × 25.1) × 100) except in The Gambia where it was calculated using iron and unsaturated iron binding capacity [26]. Iron and TSAT missing in Uganda and South Africa and transferrin missing in The Gambia