Response to Damkier

摘要

In response to the letter by Damkier [1], we welcome the further data identified from cohort study records as described by Dideriksen et?al. [2]. We note that data from four cohorts are included. We must declare that two of these [3, 4] were among the rejected references in our own systematic review [5]. While in both cases secondary descriptions of the data were readily available in the cited textbooks, the source data for methylphenidate were unpublished, and in one case could not be obtained despite us writing to the author of the cited ‘personal communication’ as is standard practice in systematic reviews. Indeed, for this data set the perils of relying on secondary sources without having access to the raw data are well illustrated in that there is a disagreement between textbooks [3] and narrative reviews [6] as to the incidence of malformations in children exposed to methylphenidate. In the other series [4], the available data suggested that there were seven malformations in a group of 96 children exposed to any of 17 sympathomimetic drugs, including 11 exposed to methylphenidate. As Dideriksen et?al. acknowledge [2], no data were provided to link the seven reports of malformations to any specific drug, and we judged that in the absence of source data specific to the risks associated with methylphenidate, it was not appropriate to include information from this series in our review. We would also question why the 11 children exposed to methylphenidate are listed in main data table of Dideriksen et?al. as having no malformations [2] when the data were described as not being specific to individual drugs.