Table of Contents:
Background: Several trials and few unsystematic reviews have been published in german speaking countries on interventions for dyslexia. No consensus on the most effective therapy could be reached. The purpose of this systematic review was to summarise the state of knowledge and find evidence for the treatment of dyslexia.
Objectives: To assess the effects of interventions for dyslexia in a german speaking population of school children.
Search strategy: Three electronic databases ( MEDLINE, PsycINFO and PsyNDEXplus Lit & AV) ending February 2004 were searched. Handsearching, cross-referencing and contacting exprets yielded additional citations.
Selection criteria: Quasi randomized controlled trials evaluating interventions for dyslexia in a german speaking population of school children were included. Interventions were any efforts to improve the ability of children with dyslexia (no fixed definition) in reading and/or spelling compared with a group of controls. The reading and spelling ability had to be measured before and after the intervention.
Data collection and analysis: 265 full text copies of relevant or potentially relevant studies were obtained and evaluated for inclusion, 56 trials were identified for this review. Due to heterogenity of the data, the results of individual studies were presented instead of conducting a meta-analysis.
Main results: The methodological quality in many studies did not match the expectations for inclusion in a meta-anaysis although the formal criterions (e.g. control group) have been fulfilled. Interventions have been initiated from the different background of educational science, psychology and medicine, therfore only few interventions could be compared with regard to contents. More trials are needed to find evidence for an effective intervention. The author outlines recommendations for those trials according to evidence based medicine in order to enhance the trial quality.