BOSTON – Amyloid imaging with the PET agent florbetaben changed the clinical management of 80% of dementia patients with a complicated or uncertain presentation, Mathieu Ceccaldi, MD, reported at the Clinical Trials on Alzheimer’s Disease conference.
The French real-world study also found that 51% of the patients had a medication change after their amyloid imaging study, said Dr. Ceccaldi, a neurologist at the Timone Hospital in Marseille, France.
“In daily practice, we are sometimes faced with complex presentations and diagnostic uncertainty in patients who have early onset dementia, atypical nonamnestic dementia, unusual behavioral symptoms, or an unexpected rate of progression,” he said. “Amyloid imaging can help resolve those issues.”
The results echo – and even exceed – those returned in an interim analysis of the large U.S.-based Imaging Dementia–Evidence for Amyloid Scanning study. The IDEAS study is examining how amyloid imaging with the PET agent florbetapir may change clinical management of dementia patients. According to data presented at last summer’s Alzheimer’s Association International Conference, knowledge of patients’ brain amyloid status changed clinical management in 68% of cases.
In France, as in the United States, amyloid imaging is not routinely available outside of clinical research programs. French patients normally undergo a lumbar puncture (LP) to obtain amyloid biomarkers. However, if an LP isn’t feasible because of the patient’s clinical condition, it’s attempted and fails, the patient refuses, or the results are unclear, then imaging may be employed.
Dr. Ceccaldi’s study comprised 205 such patients seen in any of 18 memory clinics for dementia of uncertain etiology. The study evaluated how often amyloid PET imaging with florbetaben changed the patient’s diagnosis or management and how often it contributed to improving diagnostic uncertainty.
The patients were a mean of 71 years old, with a mean Mini-Mental State Exam score of 22. An LP had been performed in 42%, but those results were either ambiguous or inconsistent with the patient’s clinical presentation. Other patients (37%) refused the procedure, and the rest had a medical contraindication to LP or had a failed procedure.
The most common diagnosis at baseline was Alzheimer’s dementia (72%), which included typical and atypical sporadic AD, young-onset AD, and rapidly progressing AD. In 16% of the cohort, the diagnosis was non-Alzheimer’s dementia, including frontotemporal dementia, primary progressive aphasia, Lewy body dementia, corticobasal degeneration, semantic dementia, and Parkinson’s disease dementia. The diagnosis was mixed dementia in 8% and nonneurodegenerative dementia in the remainder – a catchall that included vascular dementia, psychiatric disorders, and other forms of dementia.
Imaging determined that 73 patients were amyloid negative and that 132 patients were amyloid positive. These results changed diagnosis in 67% of cases overall, in 58% of amyloid-positive patients, and in 84% of amyloid-negative patients.
In the absence of cerebrospinal fluid data, florbetaben imaging significantly improved diagnostic confidence in 81% of the entire cohort (167 patients). Before imaging, clinicians rated fewer than 5% of their diagnoses as very highly confident; this rose to nearly 100% after imaging. Similarly, before imaging, about 40% of clinicians said they had weak confidence in their initial diagnoses; this dropped to fewer than 5% after imaging.
Of the 67% with a changed diagnosis (137 patients), 76 were amyloid positive, and 61 were amyloid negative. Positive scans reclassified 18 patients as having AD; negative scans removed an AD diagnosis for 38 patients.
AD was the most commonly altered diagnosis, dropping from 72% to 62% of the entire cohort. The proportion of those with non-AD dementia increased from 16% before imaging to 18% after. Mixed dementias decreased from 8% to 5%, and the number diagnosed with nonneurodegenerative dementias increased from 5% to 17%.
In particular, Dr. Ceccaldi noted, the number of patients with potentially treatable nonneurodegenerative dementia rose from 10 to 35. These included revised diagnoses for those with psychiatric disorders (from 3 patients before imaging to 11 patients after), vascular dementias (from 2 to 8 patients), and other treatable causes of dementia (from 5 to 16 patients).
All of these altered diagnoses changed management in 80% of both positive and negative patients. Among these changes were the addition of a new medication (50% of amyloid-positive patients, 18% of amyloid-negative patients), the withdrawal of a medication (15% of amyloid-negative cases), additional testing (5% of amyloid-positive cases, 20% of amyloid-negative cases), and referral to another specialist (5% of amyloid-positive patients, 20% of amyloid-negative patients).
“Our results highlight the significant utility of amyloid PET for patients with complex dementia presentations in the context of the existing work-up,” Dr. Ceccaldi said.
He reported financial relationships with a number of pharmaceutical companies, including Piramal, which developed and manufactures florbetaben.
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