‘No convincing evidence’ for zinc supplements to prevent otitis media

By Joanna Lyford, Senior medwireNews Reporter

There is no convincing evidence that zinc supplements reduce the risk of otitis media in children or adults, say the authors of an updated Cochrane review.

Zinc deficiency is common in economically disadvantaged children and zinc supplements have been shown to be effective for preventing pneumonia and other respiratory infections in children living in low- and middle-income countries.

In this review, Anjana Gulani (Max Multispeciality Centre, New Delhi, India) and Harshpal Sachdev (Sitaram Bhartia Institute of Science and Research, New Delhi, India) assessed the published literature for randomised placebo-controlled trials of zinc supplementation for preventing otitis media.

They found 12 such trials, of which 10 were suitable for inclusion. All involved children under the age of 5 years and nine of the 10 trials were conducted in low- and middle- income countries. In all trials, occurrence of otitis media was a secondary outcome, the primary outcomes usually being more serious illnesses such as pneumonia or death.

Six of the trials showed no evidence of a difference between zinc supplements and placebo on otitis media incidence or prevalence in children, Gulani and Sachdev report in The Cochrane Library.

One trial conducted within a community setting showed a possible benefit of zinc in infants from birth to 12 months but the findings were difficult to interpret, say the researchers.

However, two trials appeared to demonstrate a definite significant benefit of zinc supplementation. One involved 39 infants with marasmus, in which those given zinc supplements experienced 1.12 fewer otitis media episodes, on average, than those given placebo.

In the second trial, which involved 1621 healthy infants aged 60 days to 6 months living in a poor urban community, zinc supplementation was associated with a significantly lower incidence rate of definite otitis media, with a rate ratio of 0.69.

The authors conclude that the evidence on whether zinc supplementation can reduce the incidence of otitis media in healthy children under the age of 5 years living in low- and middle-income countries is mixed.

“There is some evidence of benefit in children being treated for marasmus (severe malnutrition), but this is based on one small trial and should therefore be treated with caution,” they write.

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