Zinc supplements for preventing otitis media.
BACKGROUND
Otitis media (inflammation of the middle ear, usually caused by infection) affects people of all ages, but is particularly common in young children. Around 164 million people worldwide have long-term hearing loss caused by this condition, 90% of them in low-income countries. Because zinc supplements prevent pneumonia in disadvantaged children, we wondered whether they prevent otitis media.


OBJECTIVE
To evaluate whether zinc supplements prevent otitis media in adults and children of different ages.


METHODS
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 2) which includes the Acute Respiratory Infection Groups' Specialised Register; MEDLINE (1950 to June Week 1 2009); and EMBASE (1974 to June 2009).


METHODS
Randomised, placebo-controlled trials of zinc supplements given at least once a week for at least a month for preventing otitis media.


METHODS
Two review authors assessed the eligibility and methodological quality of the included trials, extracted and analysed data and wrote the review. We summarised results using risk ratios or rate ratios for dichotomous data and mean differences for continuous data. We combined trial results where appropriate.


RESULTS
We identified 12 trials for inclusion, 10 of which contributed outcomes data. In trials of healthy children living in low-income communities, two trials did not demonstrate a significant difference between the zinc supplemented and placebo groups in the numbers of participants experiencing an episode of definite otitis media during follow up (3191 participants), while another trial showed a significantly lower incidence rate of otitis media in the zinc group (rate ratio 0.69, 95% confidence interval (CI) 0.61 to 0.79, n = 1621). A small trial of 39 infants undergoing treatment for severe malnutrition suggested a benefit of zinc on the mean number of episodes of otitis media (mean difference -1.12 episodes, 95% CI -2.21 to -0.03). Zinc supplements did not seem to cause any serious adverse events, but a small minority of children were reported to have vomited shortly after ingestion of the supplements.


CONCLUSIONS
Evidence on whether zinc supplementation can reduce the incidence of otitis media in healthy children under the age of five years living in low- and middle-income countries is mixed. There is some evidence of benefit in children being treated for marasmus, but this is based on one small trial and should therefore be treated with caution.
Abba
Katharine
K
International Health Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, Merseyside, UK, L3 5QA.
Gulani
Anjana
A
Sachdev
Harshpal S
HS
D002675:Child, Preschool; D002712:Chlorides / Q000627:therapeutic use; D003906:Developing Countries; D019587:Dietary Supplements; D005260:Female; D005942:Gluconates / Q000627:therapeutic use; D006801:Humans; D007223:Infant; D008297:Male; D010033:Otitis Media / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D014131:Trace Elements / Q000627:therapeutic use*; D019345:Zinc Acetate / Q000627:therapeutic use; D017967:Zinc Compounds / Q000627:therapeutic use*; D019287:Zinc Sulfate / Q000627:therapeutic use
D002712:Chlorides; D005942:Gluconates; D014131:Trace Elements; D017967:Zinc Compounds; D019287:Zinc Sulfate; C016837:zinc chloride; D019345:Zinc Acetate; C030691:gluconic acid