de Wilde A, et al. - In this prospective cohort study, the researchers explored the relationship between amyloid positron emission tomography (PET) and changes in clinical diagnosis and patient treatment in an unselected memory clinic cohort. In patients with and without dementia, both amyloid-positive and amyloid-negative results had considerable links to changes in diagnosis and treatment. This investigation acts as a bridge between validating amyloid PET in a research setting and employing this diagnostic tool in daily clinical practice.

Methods

• Between January 2015 and December 2016, amyloid PET using fluoride-18 florbetaben was offered to 866 subjects who visited the tertiary memory clinic at the VU University Medical Center as part of their routine diagnostic dementia workup.
• Of these subjects, 476 (55%) were incorporated, 32 (4%) were omitted, and 358 (41%) were not interested.
• Thirty-one patients with mild cognitive impairment from the University Medical Center Utrecht memory clinic were incorporated to supplement this sample.
• For every subject, neurologists determined a preamyloid and postamyloid PET diagnosis that included 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%.
• The neurologist also determined patient treatment in terms of auxiliary investigations, medication, and care.
• After being scanned, each patient received a clinical follow-up after 1 year.
• Post-PET changes in diagnosis, diagnostic confidence, and patient treatment were the primary outcome measures.

Results

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