Pediatric allergy and immunology : official publication of the European Society of Pediatric Allergy and Immunology
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Pediatr Allergy Immunol · Sep 2012
Review Meta AnalysisExposure to farming environments in childhood and asthma and wheeze in rural populations: a systematic review with meta-analysis.
Asthma is a chronic respiratory disorder that has become substantially more common over the past decades. One environmental factor for which particularly strong associations with asthma and allergic diseases have been described is exposure to farming environments in childhood. The aim of this systematic review was to update and extend existing narrative reviews, test for heterogeneity of effect across studies, and conduct a meta-analysis to report a summary effect measure. ⋯ The protective 'farm-effect' on asthma was reported in numerous studies. Its underlying factors ought to be studied, and promising efforts have been already made. However, the heterogeneity of the effect across studies should also be investigated because whatever causes it is a potential threat to valid synthesis of evidence and to the detection of specific protective factors.