A Cochrane review [Abstract] 1 included 47 studies with a total of 1 223 856 children from 6 months to 5 years of age. Studies were conducted in 19 countries: 30 in Asia, 16 of these in India; 8 in Africa; 7 in Latin America, and 2 in Australia. About one-third of the studies were in urban/periurban settings, and half were in rural settings; the remaining did not report settings. Most of the studies lasted about a year. All included studies reporting all-cause mortality took place in low-middle income countries.
There was a reduction in the risk of all-cause mortality and mortality due to diarrhoea for vitamin A supplementation (VAS) compared with control (table T1). There was no significant effect for VAS on mortality due to measles (RR 0.88, 95% CI 0.69 to 1.11; 6 studies, n=1 088 261), respiratory disease (RR 0.98, 95% CI 0.86 to 1.12; 9 studies, n=1 098 538), and meningitis (RR 0.57, 95% CI 0.17 to 1.88; 3 studies). VAS reduced incidence of diarrhoea and measles (table T1), and there was no significant effect on incidence of respiratory disease (Rate ratio 0.99, 95% CI 0.92 to 1.06; 11 studies, n=27 540) or hospitalisations due to diarrhoea or pneumonia. VAS reduced vitamin A deficiency by 29% compared to control. There was an increased risk of vomiting within the first 48 hours of VAS (table T1).
| Outcome | Relative effect (95% CI) | Assumed risk - Control | Corresponding risk - Vitamin A (95% CI) | Participants (studies) |
|---|---|---|---|---|
| All-cause mortality | RR 0.88 (0.83 to 0.93)1) | 26 per 1000 | 23 per 1000(22 to 24) | 1 202 382(19 studies) |
| Mortality due to diarrhoea | RR 0.88 (0.79 to 0.98) | 8 per 1000 | 7 per 1000(6 to 8) | 1 098 538(9 studies) |
| Diarrhoea incidence | Rate ratio 0.85 (0.82 to 0.87)2) | Mean episodes of diarrhoea in control group: 4.0 per child per year | 3 fewer episodes of diarrhoea per child per year (3 to 4 fewer episodes) | 77 946(15 studies) |
| Measles incidence | Rate ratio 0.50 (0.37 to 0.67) | Mean episodes of measles in control group: 0.2 per child per year | 0.015 fewer episodes per child per year (0.019 events fewer per child to 0.01 events fewer per child) | 19 566(6 studies) |
| Vitamin A deficiency | RR 0.71 (0.65 to 0.78)3) | 509 per 1000 | 361 per 1000(331 to 397) | 2 262(4 studies |
| Vomiting | RR 1.97 (1.44 to 2.69)4) | 31 per 1000 | 61 per 1000(45 to 83) | 10 541(4 studies) |
| Statistical heterogeneity 1) I2 =61%; 2) I2 =94%; 3) I2 =78%; 4) I2 =68% | ||||
| References | ||||
| Imdad A, Mayo-Wilson E, Haykal MR et al. Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age. Cochrane Database Syst Rev 2022;(3):CD008524. [PubMed].
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