Outcomes
comorbidity, non-AD, MCI, dementia, cognitive stage, AD
SECONDARY
The main outcome of the study was the proportion of participants receiving an etiological diagnosis with very high diagnostic confidence (ie, ≥90%) after 3 months (the period when the diagnostic process is generally completed) in arm 1 vs arm 2. The choice of this main outcome was based on previous studies showing that the etiological diagnosis of patients with a diagnostic confidence greater than 90% does not change following amyloid PETSecondary outcomes were change in etiological diagnosis, change in diagnostic confidence, and change in treatment plan. First, etiological diagnoses were grouped into 3 main categories: AD, including all the diagnoses involving AD (AD and mixed AD [ie, AD in comorbidity with other conditions]); non-AD, including all the remaining diagnoses/conditions without AD in comorbidity; and undetermined, when the managing physician is not confident in making any etiological diagnosis. Changes in etiological diagnosis were considered as consistent with the amyloid PET result when (1) participants with a baseline diagnosis of AD were reclassified as non-AD or undetermined after negative amyloid PET; (2) participants with a baseline diagnosis of non-AD were reclassified as AD or undetermined after positive amyloid PET; (3) participants with an undetermined diagnosis at baseline were reclassified as AD after positive amyloid PET or as non-AD after negative amyloid PET.Second, diagnostic confidence was rated only for participants who received an etiological diagnosis. Specifically, we assessed changes in diagnostic confidence only for participants with a baseline etiological diagnosis of AD or non-AD that was confirmed after 3 months.Third, to assess change in treatment plan, we determined the proportion of cognition-specific medications (eg, acetylcholinesterase inhibitors, memantine, supplements such as ginkgo or Souvenaid) that were not prescribed, introduced, discontinued, and maintained after 3 months. The introduction or discontinuation of any of these medications was considered a change in treatment plan.The analyses of the primary and secondary outcomes were performed for participants in arm 1, arm 2, and arm 3, both on the whole sample and according to cognitive stage (SCD+, MCI, and dementia). For arm 3, we assessed the proportion of participants who underwent an amyloid PET during the study, median time from baseline to performance of the scan, and reasons the scan was requested.