Zinc supplementation for the prevention of pneumonia in children aged two to 59 months

Review question

We evaluated the effectiveness of zinc supplementation to prevent pneumonia in children aged from two to 59 months.

Background

Zinc is an essential element for children's growth and development. Too little zinc is associated with increased risk of infection, particularly diarrhoea and pneumonia. Children are more prone to zinc deficiency because they are less able to absorb dietary zinc and some children, especially in low-income countries, may not have received enough zinc from their mothers before birth. Zinc supplements for children has been reported to prevent pneumonia.

Search date

We searched the literature up to October 2016. This is an update of a review published in 2010. We did not find any new studies for this update.

Study characteristics

We included six studies that investigated zinc supplements to prevent pneumonia. The studies were conducted in Bangladesh, India, Peru and South Africa and involved 5193 children aged from two to 59 months. Children received either zinc or a similar-looking treatment that did not contain zinc. In two studies, children were also given vitamin A.

Study funding sources

All included studies were funded. Of these, three explicitly mentioned that funding agencies had no role in the design and results of the study.

Key results

Zinc supplementation was significantly associated with reducing the incidence and prevalence of pneumonia among children aged from two to 59 months. On subgroup analysis, we found that a more stringent diagnosis (radiological examination) increased the reduction in pneumonia incidence.

Quality of the evidence

Overall, evidence quality was assessed as low on GRADE assessment.

Authors' conclusions: 

Zinc supplementation in children is associated with a reduction in the incidence and prevalence of pneumonia.

Read the full abstract...
Background: 

Pneumonia is a leading cause of morbidity and mortality in children younger than five years of age. Most deaths occur during infancy and in low-income countries. Daily zinc supplements have been reported to prevent acute lower respiratory tract infection (LRTI) and reduce child mortality. This is an update of a review first published in 2010.

Objectives: 

To evaluate the effectiveness of zinc supplementation in the prevention of pneumonia in children aged two to 59 months.

Search strategy: 

We searched CENTRAL (Issue 21 October 2016), MEDLINE (1966 to October 2016), Embase (1974 to October 2016), LILACS (1982 to October 2016), CINAHL (1981 to October 2016), Web of Science (1985 to October 2016) and IMSEAR (1980 to October 2016).

Selection criteria: 

Randomised controlled trials (RCTs) evaluating zinc supplementation for the prevention of pneumonia in children aged from 2 months to 59 months.

Data collection and analysis: 

Two review authors independently assessed trial quality and extracted data.

Main results: 

We did not identify any new studies for inclusion in this update. We included six studies that involved 5193 participants.

Analysis showed that zinc supplementation reduced the incidence of pneumonia by 13% (fixed-effect risk ratio (RR) 0.87; 95% confidence interval (CI) 0.81 to 0.94, six studies, low-quality evidence) and prevalence of pneumonia by 41% (random-effects RR 0.59; 95% CI 0.35 to 0.99, one study, n = 609, low-quality evidence). On subgroup analysis, we found that zinc reduced the incidence of pneumonia defined by specific clinical criteria by 21% (i.e. confirmation by chest examination or chest radiograph) (fixed-effect RR 0.79; 95% CI 0.71 to 0.88, four studies, n = 3261), but had no effect on lower specificity pneumonia case definition (i.e. age-specific fast breathing with or without lower chest indrawing) (fixed-effect RR 0.95; 95% CI 0.86 to 1.06, four studies, n = 1932).

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