for the main comparison.
| Vitamin A supplementation for preventing morbidity and mortality in children from 6 months to 5 years of age | ||||||
|
Patient or population: children aged between 6 months and 5 years Intervention: vitamin A supplementation Comparison: placebo or usual care | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | Number of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Control | Vitamin A | |||||
|
All‐cause mortality Follow‐up: 12‐96 weeks |
Study population | RR 0.88 (0.83 to 0.93) | 1,202,382 (19 studies) |
++++ Highb | Random‐effects RR 0.76 (95% CI 0.66 to 0.88) |
|
| 26 per 1000a |
23 per 1000 (22 to 24) |
|||||
|
Mortality due to diarrhoea Follow‐up: 48‐104 weeks |
Study population | RR 0.88, (0.79 to 0.98) | 1,098,538 (9 studies) | ++++ Highb | Total number of participants reflects number randomised to studies. The analysis combined cumulative risk and risk per 1000 years follow‐up | |
| 8 per 1000a |
7 per 1000 (6 to 8) |
|||||
|
Mortality due to measles Follow‐up: 52 to 104 weeks |
Study population | RR 0.88, (0.69 to 1.11) | 1,088,261 (6 studies) | ++OO Lowc,d |
Total number of participants reflects number randomised to studies. The analysis combined cumulative risk and risk per 1000 years follow‐up | |
| 2 per 10,000a |
2 per 1000 (1 to 2) |
|||||
|
Mortality due to LRTI Follow‐up: 48‐104 weeks |
Study population | RR 0.98, (0.86 to 1.12) | 1,098,538 (9 studies) | ++OO Lowc,d | Total number of participants reflects number randomised to studies. The analysis combined cumulative risk and risk per 1000 years follow‐up | |
| 4 per 10,000a |
4 per 1000 (3 to 5) |
|||||
|
Diarrhoea incidence Mean episodes per child per year Follow‐up: 24‐60 weeks |
Study population | Rate ratio 0.85, 95% CI 0.82 to 0.87 | 77,946 (15 studies) | ++OO Lowc,f | — | |
| Mean episodes of diarrhoea in control group: 4.0 per child per yeare | VAS led to 3 fewer episodes of diarrhoea per child per year (3 to 4 fewer episodes) | |||||
|
Measles incidence Mean episodes of measles per child per year Follow‐up: mean 52 weeks |
Study population | Rate ratio 0.50, 95% CI 0.37 to 0.67 | 19,566 (6 studies) | ++O Moderatec |
— | |
| Mean episodes of measles in control group: 0.2 per child per yeare | VAS led to 0.015 fewer episodes per child per year (0.019 events fewer per child to 0.01 events fewer per child) | |||||
|
LRTI incidence Mean episodes per child per year Follow‐up: mean 52 weeks |
Study population | Rate ratio 0.99, 95% CI 0.92 to 1.06 | 27, 540 (11 studies) | ++OO Lowc,d |
— | |
| Mean episodes of LRTI in control group: 0.1 episodes per child per yeare | VAS led to 0.1 more episodes of LRTI per child per year (0.1 fewer episodes to 0.1 more episodes) | |||||
|
Bitot's spots incidence Follow‐up: mean 80.72 weeks |
Study population | RR 0.42, 95% CI 0.33 to 0.53 | 1,063,278 (5 studies) | +++O Moderatec |
— | |
| 35 per 1000a |
15 per 1000 (12 to 19) |
|||||
|
Night blindness incidence Follow‐up: 52 to 68 weeks |
Study population | RR 0.32, 95% CI 0.21 to 0.50 | 22,972 (2 studies) |
+++O Moderatec |
— | |
| 4 per 1000g |
1 per 1000 (1 to 2) |
|||||
|
Vitamin A deficiency Follow‐up: mean 54.5 weeks |
Study population | RR 0.71, 95% CI 0.65 to 0.78 | 2262 (4 studies) | +++O Moderatec | — | |
| 509 per 1000g |
361 per 1000 (331 to 397) |
|||||
|
Vomiting Follow‐up: 0.14 to 52 weeks |
Study population | RR 1.97, 95% CI 1.44 to 2.69 | 10541 (4 studies) | +++O Moderatec | — | |
| 31 per 1000g |
61 per 1000 (45 to 83) |
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| *The basis for the assumed risk (for example, the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; DEVTA: deworming and enhanced vitamin A; LRTI: lower respiratory tract infection; RR: risk ratio; VAS: vitamin A supplementation | ||||||
| GRADE Working Group grades of evidence High quality: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate quality: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low quality: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low quality: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect. | ||||||
aBased on control group mortality risk in DEVTA trial 2013. bWe acknowledge that the addition of DEVTA trial 2013 results decreased the overall effect size for this outcome compared to previous analysis for this review. However, we think that vitamin A has robust effects on mortality as the direction of effect is in favour of intervention in most of the studies and summary estimate remains statistically significant irrespective of the use of random‐ or fixed‐effect models for meta‐analysis. cDowngraded 1 level due to serious risk of bias of included studies in analysis (concerns with randomisation procedures, completeness, and reporting of outcome data in the included studies). dDowngraded 1 level due to serious imprecision (wide CIs around the pooled effect estimate suggest both appreciable benefit and harm with vitamin A). eBased on control event rate in Chowdhury 2002. fDowngraded 1 level due to serious inconsistency (I2 was 94%, and the results of Herrera 1992; Cheng 1993 and Chowdhury 2002 demonstrated clear evidence of benefit and were discordant with the results of the other studies). gRisk based on control event rates from the included studies.