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Original Investigation
September 2018

Association of Amyloid Positron Emission Tomography With Changes in Diagnosis and Patient Treatment in an Unselected Memory Clinic Cohort: The ABIDE Project

Author Affiliations
  • 1Department of Neurology & Alzheimer Center, Amsterdam Neuroscience, VU University Medical Center, Amsterdam, the Netherlands
  • 2Department of Epidemiology & Biostatistics, Amsterdam Neuroscience, VU University Medical Center, Amsterdam, the Netherlands
  • 3Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, the Netherlands
  • 4Department of Radiology & Nuclear Medicine, Amsterdam Neuroscience, VU University Medical Center, Amsterdam, the Netherlands
  • 5Department of Medical Psychology, Amsterdam Neuroscience, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
  • 6Institutes of Neurology and Healthcare Engineering, University College London, London, England
  • 7Piramal Imaging GmbH, Berlin, Germany
  • 8BV Cyclotron, Amsterdam, the Netherlands
JAMA Neurol. 2018;75(9):1062-1070. doi:10.1001/jamaneurol.2018.1346
Key Points

Question  What is the association between amyloid positron emission tomography (PET) and changes in clinical diagnosis and patient treatment in an unselected memory clinic cohort?

Findings  In this prospective cohort study, the etiological diagnosis changed for 25% of patients after amyloid PET, more often due to a negative than a positive PET result. Diagnostic confidence increased, and for several patients, there was a change in the treatment received by patients post-PET.

Meaning  Amyloid-positive and amyloid-negative results were associated with changes in diagnosis and treatment, both for patients with and without dementia.

Abstract

Importance  Previous studies have evaluated the diagnostic effect of amyloid positron emission tomography (PET) in selected research cohorts. However, these research populations do not reflect daily practice, thus hampering clinical implementation of amyloid imaging.

Objective  To evaluate the association of amyloid PET with changes in diagnosis, diagnostic confidence, treatment, and patients’ experiences in an unselected memory clinic cohort.

Design, Setting, and Participants  Amyloid PET using fluoride-18 florbetaben was offered to 866 patients who visited the tertiary memory clinic at the VU University Medical Center between January 2015 and December 2016 as part of their routine diagnostic dementia workup. Of these patients, 476 (55%) were included, 32 (4%) were excluded, and 358 (41%) did not participate. To enrich this sample, 31 patients with mild cognitive impairment from the University Medical Center Utrecht memory clinic were included. For each patient, neurologists determined a preamyloid and postamyloid PET diagnosis that existed 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, the neurologist determined patient treatment in terms of ancillary investigations, medication, and care. Each patient received a clinical follow-up 1 year after being scanned.

Main Outcomes and Measures  Primary outcome measures were post-PET changes in diagnosis, diagnostic confidence, and patient treatment.

Results  Of the 507 patients (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. Amyloid PET results were positive for 242 patients (48%). 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). Post-PET changes in suspected etiology occurred more frequently in patients older (>65 years) than younger (<65 years) than the typical age at onset of 65 years (74 of 257 [29%] vs 51 of 250 [20%]; P < .05). Mean diagnostic confidence (SD) increased from 80 (13) to 89 (13%) (P < .001). In 123 patients (24%), there was a change in patient treatment post-PET, mostly related to additional investigations and therapy.

Conclusions and Relevance  This prospective diagnostic study provides a bridge between validating amyloid PET in a research setting and implementing this diagnostic tool in daily clinical practice. Both amyloid-positive and amyloid-negative results had substantial associations with changes in diagnosis and treatment, both in patients with and without dementia.

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