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Arch Dis Child. 2007 June; 92(6): 559.
PMCID: PMC2066145

Concerns with the linear regression model

I would like to thank the authors of the paper entitled “Recovery of consciousness after epileptic seizures in children” for their hard work trying to answer a very important and practical question facing clinicians treating a postictal child.1 However, I would like to raise some concerns regarding their analysis using the linear regression model they described, which might have affected their findings and thus their recommendations.

First, the two explanatory variables in the model, “duration of seizure” and “use of emergency drugs”, may not be truly independent, thereby violating one of the assumptions for using this model. This is because emergency anticonvulsant therapy is administered to children with a prolonged convulsion, as advised in most guidelines, while short seizures usually require no therapy.

The second point is that the “acute symptomatic”, “idiopathic” and “remote symptomatic” explanatory variables in the model are not truly separate explanatory variables, but constitute (like “febrile convulsion”, which was not considered) some of the possible values which a single explanatory variable (seizure aetiology) might take.

I hope these concerns did not affect the results of the study nor the conclusions and recommendations of the authors for this important clinical question.


Competing interests: None declared.


1. Allen J E, Ferrie C D, Livingston J H. et al Recovery of consciousness after epileptic seizures in children. Arch Dis Child 2007. 9239–42.42 [PMC free article] [PubMed]

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