Objectives: The purpose of this review is to provide a systematic analysis of all available studies in which chelation therapy was used to treat ASD. This review comprises efforts to (a) evaluate the evidence regarding chelation therapy, (b) guide and inform practitioners in decisions of whether to implement chelation therapy, and (c) identify directions for future research.
Methods: Database, hand, and ancestry searches were performed to identify intervention studies published before or during December 2010 that involved administration of chelation therapy. Articles meeting inclusion criteria were analyzed in terms of (a) characteristics of the studies (e.g., participants, therapy procedures), (b) therapy outcomes, and (c) certainty of the evidence. When possible, effect sizes for individual studies were estimated and synthesized using calculations for Hedges’ g. The therapy outcomes from studies for which quantitative summarization was not possible (e.g., case studies) were summarized and synthesized narratively.
Results: Database, hand, and ancestry searches identified 13 studies involving the administration of chelation therapy. Studies reported a wide range of therapy outcomes, ranging from substantial improvements in social and communicative functioning, no apparent effect, and death. Appraisal of the studies’ certainty of evidence reveals the support for use of chelation therapy is weak. All studies reporting favourable outcomes possessed major flaws.
Conclusions: The current scientific literature does not support chelation therapy as treatment for ASD. The lack of support and the health risks of chelation therapy suggest it should not be administered to individuals with ASD. Should additional research be conducted on chelation therapy, it should be limited to evaluation of naturally occurring, food-based chelators, which have received little attention in the literature. However, due to the lack of support for the heavy metal aetiology, little rationale exists for performing such research.
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