Tuesday, 23rd of February 2010 |
Department of International Health, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
*Corresponding author. Department of International Health, The Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, E8527, Baltimore, MD 21205, USA. Email: rblack@jhsph.edu
Abstract |
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Background Routine zinc supplementation is a potential intervention for the prevention of acute lower respiratory infection (ALRI) in developing countries. However, discrepant findings from recent randomized trials remain unexplained.
Methods Randomized trials of zinc supplementation in young children in developing countries were identified by a systematic literature review. Trials included in the meta-analysis met specific criteria, including participants <5 years of age, daily/weekly zinc and control supplementation for greater than 3 months, active household surveillance for respiratory morbidity and use of a case definition that included at least one sign of lower respiratory tract illness. ALRI case definitions were classified on the basis of specificity/severity. Incidence rate ratios (IRRs) were pooled by random-effects models. Meta-regression and sub-group analysis were performed to assess potential sources of between-study heterogeneity.
Results Ten trials were eligible for inclusion (n = 49 450 children randomized). Zinc reduced the incidence of ALRI defined by specific clinical criteria [IRR 0.65, 95% confidence interval (CI) 0.52–0.82], but had no effect on lower-specificity ALRI case definitions based on caregiver report (IRR 1.01, 95% CI 0.91–1.12) or World Health Organization ‘non-severe pneumonia’ (0.96, 95% CI 0.86–1.08). By meta-regression, the effect of zinc was associated with ALRI case definition, but not with mean baseline age, geographic location, nutritional status or zinc dose.
Conclusions Routine zinc supplementation reduced the incidence of childhood ALRI defined by relatively specific clinical criteria, but the effect was null if lower specificity case definitions were applied. The choice of ALRI case definition may substantially influence inferences from community trials regarding the efficacy of preventive interventions.
Keywords Zinc, pneumonia, respiratory tract infections, developing countries, meta-analysis, systematic review
Accepted 14 December 2009
2) ORAL ZINC FOR TREATING DIARRHEA IN CHILDREN
This Cochrane review, also available at http://www.cochrane.org/reviews/en/ab005436.html finds evidence for zinc on morbidity, but not mortality, from child diarrhea."In areas where diarrhoea is an important cause of child mortality, research evidence shows zinc is clearly of benefit in children aged six months or more."
Lazzerini M, Ronfani L SummaryOral zinc supplementation for treating diarrhoea in childrenIn developing countries, millions of children suffer from severe diarrhoea every year. This is due to infection and malnutrition, and many die from dehydration due to the diarrhoea. Giving fluids by mouth (using an oral rehydration solution) has been shown to save children's lives, but it seems to have no effect on the length of time the children suffer with diarrhoea. Children in developing countries are often zinc deficient. Zinc supplementation is a possible treatment for diarrhoea though it can have adverse effects if given in high doses. The review of trials identified 18 trials involving 6165 children of all ages. Zinc reduced the time that children over the age of six months suffered from symptoms of acute or persistent diarrhoea. However, there were insufficient data to see any impact on the number of children who died. More children vomited when given zinc, but it was considered that the benefits outweighed these adverse effects. Zinc seemed to have no impact on children aged less than six months. In areas where diarrhoea is an important cause of child mortality, research evidence shows zinc is clearly of benefit in children aged six months or more with diarrhoeal diseases. This is a Cochrane review abstract and plain language summary, prepared and maintained by The Cochrane Collaboration, currently published in The Cochrane Database of Systematic Reviews 2009 Issue 3, Copyright © 2009 The Cochrane Collaboration. Published by John Wiley and Sons, Ltd.. The full text of the review is available in The Cochrane Library (ISSN 1464-780X). This version first published online: July 16. 2008 AbstractBackgroundDiarrhoea causes around two million child deaths annually. Zinc supplementation could help reduce the duration and severity of diarrhoea, and is recommended by the World Health Organization and UNICEF. ObjectivesTo evaluate oral zinc supplementation for treating children with acute or persistent diarrhoea. Search strategyIn November 2007, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2007, Issue 4), MEDLINE, EMBASE, LILACS, CINAHL, mRCT, and reference lists. We also contacted researchers. Selection criteriaRandomized controlled trials comparing oral zinc supplementation (≥ 5 mg/day for any duration) with placebo in children aged one month to five years with acute or persistent diarrhoea, including dysentery. Data collection and analysisBoth authors assessed trial eligibility and methodological quality, extracted and analysed data, and drafted the review. Diarrhoea duration and severity were the primary outcomes. We summarized dichotomous outcomes using risk ratios (RR) and continuous outcomes using mean differences (MD) with 95% confidence intervals (CI). Where appropriate, we combined data in meta-analyses (using the fixed- or random-effects model) and assessed heterogeneity. Main resultsEighteen trials enrolling 6165 participants met our inclusion criteria. In acute diarrhoea, zinc resulted in a shorter diarrhoea duration (MD -12.27 h, 95% CI -23.02 to -1.52 h; 2741 children, 9 trials), and less diarrhoea at day three (RR 0.69, 95% CI 0.59 to 0.81; 1073 children, 2 trials), day five (RR 0.55, 95% CI 0.32 to 0.95; 346 children, 2 trials), and day seven (RR 0.71, 95% CI 0.52 to 0.98; 4087 children, 7 trials). The four trials (1458 children) that reported on diarrhoea severity used different units and time points, and the effect of zinc was less clear. Subgroup analyses by age (trials with only children aged less than six months) showed no benefit with zinc. Subgroup analyses by nutritional status, geographical region, background zinc deficiency, zinc type, and study setting did not affect the results' significance. Zinc also reduced the duration of persistent diarrhoea (MD -15.84 h, 95% CI -25.43 to -6.24 h; 529 children, 5 trials). Few trials reported on severity, and results were inconsistent. No trial reported serious adverse events, but vomiting was more common in zinc-treated children with acute diarrhoea (RR 1.71, 95% 1.27 to 2.30; 4727 children, 8 trials). Authors' conclusionsIn areas where diarrhoea is an important cause of child mortality, research evidence shows zinc is clearly of benefit in children aged six months or more. |
3) ZINC AND LOW OSMOLARITY ORS FOR DIARRHEA: A RENEWED CALL TO ACTION
ABSTRACT
In 2004, WHO and the United Nations Children's Fund (UNICEF) released a joint statement recommending a new lower osmolarity oral rehydration salts (ORS) formulation and zinc supplementation for diarrhoea management. More than 5 years later, diarrhoea remains the second leading cause of death and few children in developing countries are receiving these life-saving interventions. Many countries are stalled in the technicalities of adapting national policy, while others struggle to find the funds for start-up activities. For nearly all countries, zinc supplements for children are not available locally; thus, zinc procurement continues to be a major obstacle. Global resources have not been sufficient to bring diarrhoea management to the forefront; thus, the introduction of these new recommendations has remained slow. Revitalizing diarrhoea management must become an international priority if we are going to reduce the burden of diarrhoea deaths and overall child mortality around the world.
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