Objective: To describe the characteristics of patients initially diagnosed with idiopathic Parkinson’s Disease (PD) and with abnormal dopamine transporter (DAT) imaging who have a change in diagnosis within 3 years.

Background: In patients with early parkinsonism referred for enrollment in PD clinical trials, 6-13 % have a change of diagnosis. This can have detrimental consequences on trial results. DAT imaging can help improve diagnostic accuracy, but DAT imaging abnormalities are not specific to PD.

Methods: Data used in the preparation of this article were obtained from the Parkinson’s Progression Markers Initiative (PPMI) database (www.ppmi-info.org/data). For up-to-date information on the study, visit www.ppmi-info.org. PPMI is a multicenter, observational study that enrolled 423 individuals with a diagnosis of PD of 2 or less years duration and with abnormal DAT imaging. Participants were assessed at least annually and diagnosis was documented by the site investigator. Subjects who had at least 3 years of follow-up were included in this analysis. Characteristics of those that had a change in diagnosis are described, and compared to those with stable diagnosis. Non-parametric and fisher’s exact tests were applied as appropriate.

Results: 390 subjects were included. Eight patients had a change in diagnosis: Multiple System Atrophy (MSA) in 5, Corticobasal Degeneration in 1, and Dementia with Lewy Bodies in 2. Revision of diagnosis occurred between 2 and 5.2 years from enrollment. MDS-UPDRS III score was higher (p=0.01), DAT binding lower (p=0.01), and UPSIT (raw score) higher (p=0.03) in those whose diagnosis changed.

Conclusions: Diagnosis remains stable in most individuals diagnosed with idiopathic PD and with abnormal DAT imaging, but a small number are later diagnosed with another neurodegenerative parkinsonian syndrome. Clinical and biomarker abnormalities were greater at baseline in those whose diagnosis changed. A composite of these measures could be of utility for distinguishing idiopathic PD from atypical parkinsonian disorders. Increased diagnostic accuracy would be of value both clinically and for clinical trial enrollment.

References: 1: Stoffers, Diederick, Jan Booij, Lisette Bosscher, Ania Winogrodzka, Erik C. Wolters, and Henk W. Berendse. 2005. “Early-Stage [123I]beta-CIT SPECT and Long-Term Clinical Follow-up in Patients with an Initial Diagnosis of Parkinson’s Disease.” European Journal of Nuclear Medicine and Molecular Imaging 32 (6):689–95. 2: Jankovic, Joseph, Ali H. Rajput, Michael P. McDermott, and Daniel P. Perl. 2000. “The Evolution of Diagnosis in Early Parkinson Disease.” Archives of Neurology 57 (3). American Medical Association:369–72.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/revision-of-diagnosis-in-early-parkinsonism-with-abnormal-dopamine-transporter-imaging-a-case-series-from-the-ppmi-study/