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Deworming drugs for treating soil‐transmitted intestinal worms in children: effects on growth and school performance

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Abstract

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Background

Review status: Current question ‐ update pending: a search conducted in July 2011 has been passed to authors for assessment. ("Published notes" explains the review status categories).

In areas where intestinal worm infections occur, the World Health Organization recommends treating all school children at regular intervals with deworming drugs to improve growth and school performance. The evidence base for this policy needs to be established for countries to commit resources to implement these programmes.

Objectives

To summarize the effects of deworming drugs used to treat soil‐transmitted intestinal worms (nematode geohelminths) on growth and school performance in children.

Search methods

In May 2007, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2007, Issue 2), MEDLINE, EMBASE, LILACS, mRCT, and reference lists.

Selection criteria

Randomized and quasi‐randomized controlled trials (RCTs) comparing deworming drugs for geohelminth worms with placebo or no treatment in children aged 16 years or less, reporting on growth, nutritional status, school performance, or cognition tests.

Data collection and analysis

Two authors independently assessed the trials and evaluated methodological quality; one author extracted data, and another checked a sample. Continuous data were analysed using the mean difference (MD) with 95% confidence intervals (CI). The random‐effects model (RE model) was used in the presence of statistically significant heterogeneity.

Main results

Thirty‐four RCTs, including six cluster‐RCTs, met the inclusion criteria. Four trials had adequate allocation concealment, and three cluster‐RCTs failed to take design effects into account in their analysis. Weight increased after one dose of a deworming drug (MD 0.34 kg, 95% CI 0.05 to 0.64, RE model; 2448 children, 9 trials); however, there was considerable heterogeneity between trials that was not explained by background intestinal worm infection or intensity. A meta‐analysis of multiple dose trials reporting on outcomes within a year of starting treatment showed no significant difference in weight gain (1714 children, 6 trials); however, one cluster‐RCT did show effects on weight at one year in a subgroup analysis. In the seven multiple dose trials with follow up beyond 12 months, only one showed a significant increase in weight. Six of seven trials reported clear data on cognitive tests and school performance: five reported no significant effects, and one showed some improvements in three out of 10 cognitive tests.

Authors' conclusions

Deworming drugs used in targeted community programmes may be effective in relation to weight gain in some circumstances but not in others. No effect on cognition or school performance has been demonstrated.

PICOs

Population
Intervention
Comparison
Outcome

The PICO model is widely used and taught in evidence-based health care as a strategy for formulating questions and search strategies and for characterizing clinical studies or meta-analyses. PICO stands for four different potential components of a clinical question: Patient, Population or Problem; Intervention; Comparison; Outcome.

See more on using PICO in the Cochrane Handbook.

Plain language summary

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Deworming drugs for treating soil‐transmitted intestinal worms in children: effects on growth and school performance

About a quarter of the world's population is infected with one or more soil‐transmitted worms. The main soil‐transmitted worms are roundworms, hookworms, and whipworms. Infections are widely distributed in tropical and subtropical areas, with most infected people having more than one type of worm. The burden of disease falls disproportionately on the poor, where there is inadequate sanitation, overcrowding, low levels of education, and lack of access to health care. These infections cause malnutrition and poor growth for children, and some studies have suggested an association with poor performance at school. Improved sanitation and hygiene are likely to be helpful. There are also three basic strategies for using drugs to treat these infections: (1) individual treatment based on a diagnosis of infection (selective treatment); (2) groups at increased risk are treated (targeted treatment); and (3) treating whole communities whether people have the infection or not (universal treatment). The targeted treatment is the one generally used. This review of trials looked at targeted treatment with a range of deworming drugs for children, particularly focusing on growth and school performance. Thirty‐four trials were identified. These trials either looked at single or multiple doses, but only some assessed school performance. After just one dose children's weight improved, and more doses did not seem to improve this further. Only one of the seven trials that assessed school performance found any positive effect, so it seems unlikely that there is a benefit here. Two trials looked at adverse events, but the trials were small. Further research is needed.