Dilemmas in the interpretation of diagnostic accuracy studies on presurgical workup for epilepsy surgery.

We conducted a systematic review to determine which noninvasive technologies should be used in the workup for epilepsy surgery to identify structural or functional abnormalities to help locate the site of seizure onset. The review focused on patients where there was insufficient confidence, in either the decision to go to surgery or the site at which surgery should be conducted, after the initial clinical examination. The majority of the studies identified were single-gate diagnostic accuracy studies; none were randomized controlled trials, and only one reported the effect of the test results on the decision making process. It became apparent that the data derived from diagnostic accuracy studies could not be used to answer the review question. This article focuses on the methods used to extract data from the diagnostic accuracy studies, the difficulties interpreting the resulting data, why such studies are not an appropriate study design in this setting, and how the evidence-base can be improved.