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Can We Reliably Establish Parkinson's Disease Subtypes In De Novo Patients: Results From The PPMI Study

Simuni, T; Caspell-Garcia, C; Coffey, C; Uribe, L; Lasch, S; Jennings, D; Tanner, C; Marek, K; The Parkinson\'s Progression Markers Initiative
MDS: Stockholm, Sweden
Download Presentation: 1064 PPMI-Subtypes-Poster-JUNE-2014-MDS.pdf
To determine the frequency and stability over time of the sub group characterization of the tremor dominant (TD) versus postural instability gait disorder dominant (PIGD) Parkinson's disease (PD) in de novo patients.

While the unifying feature of PD is Lewy body pathology, there is a substantial body of literature on the clinical sub classification of PD, specifically into TD versus PIGD subtype. The former has been shown to be associated with the slower progression and less accumulation of disability. However, there is limited data on the stability of this classification especially in early disease. Collecting such information is important especially if this classification is to be used for the clinical prognostication and correlation with the biomarkers.

Parkinson's Progression Markers Initiative (PPMI) is an international study of de novo, untreated (at enrolment) PD patients and healthy controls (HCs). At baseline, participants were assessed wide range of motor and non-motor scales including The Movement Disorder Society Unified Parkinson's disease Rating Scale (MDS-UPDRS). TD versus PIGD subtype was defined based on the formula published by Stebbins et al(Stebbins, Goetz et al. 2013). Subtype classification was repeated at each study visit.

423 PD patients and 196 HCs were recruited into the study. As of December 2013, baseline and one year data was available for 269 subjects. 185 were classified as TD at baseline. Of these at 12 months, 156 (84%) were also classified as TD; 13 (7%) as ?Indeterminate? and 16 (9%) as PIGD. 52 were classified as PIGD at baseline. Of these at 12 months, 33 (63%) remained PIGD, 15 (29%) were classified as TD and 4 (8%) as ?Indeterminate?. These changes were not affected by the start of dopaminergic treatment.

Clinical classification of PD into TD versus PIGD subtype is subject to substantial variability over first year in PD de novo cohort. PIGD subjects at baseline seem about twice as likely to have their status change at 12 months versus those classified as TD. More data are necessary to establish longitudinal stability of this classification over a longer period of time. This ?instability ? has to be taken into consideration specifically when establishing correlation with the biomarkers and for long term prognostication.