Haemoglobin (g/L)* | Ferritin (ng/mL)* | Anaemia† | Iron deficiency† | Iron deficiency anaemia† | |
Weekly frequency | |||||
Frequent (3–7 times/week) | |||||
n | 132 | 88 | 57 | 44 | 24 |
Estimate | 6.6 | 20.9 | 0.62 | 0.31 | 0.20 |
95% CI | (5.6 to 7.6) | (18.2 to 23.7) | (0.56 to 0.69) | (0.24 to 0.38) | (0.13 to 0.32) |
Intermittent (1–2 times/week) | |||||
n | 32 | 18 | 10 | 4 | 3 |
Estimate | 4.8 | 6.7 | 0.61 | 0.24 | 0.22 |
95% CI | (3.4 to 6.2) | (3.7 to 9.6) | (0.41 to 0.92) | (0.09 to 0.66) | (0.06 to 0.77) |
P value for interaction | 0.14 | <0.001 | 0.87 | 0.73 | 0.91 |
Duration‡ | |||||
1–3 months | |||||
n | 96 | 59 | 27 | 18 | 6 |
Estimate | 7.3 | 13.9 | 0.53 | 0.38 | 0.23 |
95% CI | (6.0 to 8.6) | (11.7 to 16.1) | (0.45 to 0.62) | (0.25 to 0.57) | (0.07 to 0.81) |
4–6 months | |||||
n | 53 | 41 | 34 | 26 | 19 |
Estimate | 5.7 | 25.1 | 0.63 | 0.21 | 0.15 |
95% CI | (4.3 to 7.0) | (20.0 to 30.1) | (0.54 to 0.72) | (0.15 to 0.30) | (0.11 to 0.22) |
≥7 months | |||||
n | 18 | 7 | 8 | 4 | 2 |
Estimate | 2.6 | 11.8 | 0.84 | 0.84 | 0.86 |
95% CI | (1.4 to 3.8) | (5.9 to 17.7) | (0.69 to 1.03) | (0.67 to 1.06) | (0.63 to 1.18) |
P value for interaction | 0.01 | 0.01 | 0.07 | 0.05 | <0.001 |
Dose | |||||
Low (1st tertile for age) | |||||
n | 59 | 41 | 27 | 17 | 13 |
Estimate | 4.4 | 13.7 | 0.68 | 0.33 | 0.26 |
95% CI | (3.2 to 5.6) | (9.5 to 17.9) | (0.57 to 0.81) | (0.22 to 0.50) | (0.17 to 0.41) |
Moderate (2nd tertile for age) | |||||
n | 32 | 22 | 23 | 17 | 10 |
Estimate | 8.6 | 26.0 | 0.55 | 0.27 | 0.08 |
95% CI | (5.9 to 11.4) | (19.0 to 32.9) | (0.47 to 0.66) | (0.18 to 0.40) | (0.05 to 0.14) |
High (3rd tertile for age) | |||||
n | 37 | 25 | 9 | 9 | 2 |
Estimate | 7.2 | 16.2 | 0.64 | 0.24 | 0.08 |
95% CI | (5.3 to 9.1) | (13.4 to 19.0) | (0.49 to 0.84) | (0.12 to 0.47) | (0.01 to 0.69) |
P value for interaction | 0.004 | 0.008 | 0.44 | 0.82 | 0.02 |
*Weighted mean difference.
†Pooled risk ratio.
‡Trials of short duration were more likely to have a higher proportion of patients with anaemia. No significant associations were observed between duration and haemoglobin, anaemia, iron deficiency and iron deficiency anaemia outcomes after controlling for baseline anaemia. After control for anaemia, an increase in serum ferritin was associated with trials of longer duration (see online supplemental appendix 5).