de Wilde A, et al. - In an unselected memory clinic cohort, researchers investigated the correlation of amyloid positron emission tomography (PET) with changes in diagnosis, diagnostic confidence, treatment, and patients’ experiences. This prospective diagnostic study allows a bridge between validating amyloid PET in a research setting and applying this diagnostic tool to daily clinical practice. Findings revealed considerable associations of both amyloid-positive and amyloid-negative results with changes in diagnosis and treatment, both in patients with and without dementia.

Methods

• Between January 2015 and December 2016, 866 patients who visited the tertiary memory clinic at the VU University Medical Center were offered amyloid PET using fluoride-18 florbetaben as part of a routine diagnostic dementia workup.
• Of these, researchers included 476 (55%) and excluded 32 (4%); 358 (41%) patients did not participate.
• To supplement this sample, they included 31 patients with mild cognitive impairment from the University Medical Center Utrecht memory clinic.
• Neurologists assessed a preamyloid and postamyloid PET diagnosis for each patient that consisted of both a clinical syndrome (dementia, mild cognitive impairment, or subjective cognitive decline) and a suspected etiology (Alzheimer disease [AD] or non-AD), with a confidence level ranging from 0% to 100%.
• In addition, patient treatment, in terms of ancillary investigations, medication, and care, was determined by the neurologist.
• One year after being scanned, they followed-up each patient.
• Post-PET changes in diagnosis, diagnostic confidence, and patient treatment were assessed as primary outcome measure.

Results

• Among the 507 patients (mean [SD] age, 65 (8) years; 201 women [39%]; mean [SD] Mini-Mental State Examination score, 25 [4]), 164 (32%) displayed AD dementia, 70 (14%) non-AD dementia, 114 (23%) mild cognitive impairment, and 159 (31%) subjective cognitive decline.
• For 242 patients (48%), positive amyloid PET results were observed.
• After undergoing amyloid PET, change in the suspected etiology was noted for 125 patients (25%), more often due to a negative (82 of 265 [31%]) vs a positive (43 of 242 [18%]) PET result (P < .01).
• Older patients (>65 years) displayed post-PET changes in suspected etiology more frequently than those younger (<65 years) than the typical age of onset at 65 years (74 of 257 [29%] vs 51 of 250 [20%]; P < .05).
• Increase in mean diagnostic confidence (SD) from 80 (13) to 89 (13%) was noted (P < .001).
• A change in patient treatment post-PET was noted in 123 patients (24%), mostly related to additional investigations and therapy.