In reply
We appreciate the interest of Dr Claus in our article.1 The main purpose of our study was to report our accuracy rates for the diagnosis of AD and to discuss the incorrectly diagnosed cases, including the presence of features that seemed to stand out among the cases as potentially atypical for AD. We did not set out to define the frequencies, among either the incorrectly diagnosed cases or the AD cases, of these features (or red flags). As Dr Claus points out, this is a limitation of the study in that the predictive values of these red flags were not determined.To further investigate these issues, we plan to follow up this investigation with a retrospective study, looking at the frequencies of the specific red flags among our incorrectly diagnosed cases, and to compare these findings with a cohort of correctly diagnosed patients with AD. The red