Added diagnostic accuracy after flutemetamol PET scanning in young patients with dementia in an academic memory clinic setting

IntroductionA timely diagnosis of Alzheimers Disease (AD) in an early stage of dementia is important to support timely access to treatment, advice, and care. The aim of this study was to estimate the diagnostic accuracy of [18F]flutemetamol PET in addition to the usual diagnostic workup for the diagnosis of AD in a memory clinic population with young onset dementia by means of a panel reference-based etiology diagnosis. Methodsin an academic memory clinic early onset dementia cohort (n=211) the nosological diagnosis was set by usual diagnostic workup and after including [18F]flutemetamol amyloid PET in a stepwise approach. To assess the change in proportion correctly diagnosed, the diagnosis with and without [18F]flutemetamol PET was related to a panel-based reference standard, serving as gold standard, consisting of 3 neurologists who relied on available clinical information over 2-year follow-up (n=152; blinded for PET). ResultsThe panel majority nosology was set as a reference diagnosis in 122 participants, leaving 30 (20%) participants with no majority reached. In 107 (88%) cases post-PET was in line with the reference, and in 103 (84%) the pre-PET diagnosis was in line with the reference. The difference was 3.3% (95% CI -3.5% to 10.1%; p=0.424). Discussion[18F]flutemetamol PET did not significantly improve the diagnostic accuracy in young patients with dementia in an academic memory clinic setting. The secondary analyses provided several indications for future research in a narrower subsample of persons with (very) high diagnostic uncertainty and to assess patient relevant health outcomes.