Abstract
Background: Various classifications have been proposed to subtype Parkinson's disease (PD) based on their motor phenotypes. However, the stability of these subtypes has not been properly evaluated.Objective: The goal of this study was to understand the distribution of PD motor subtypes, their stability over time, and baseline factors that predicted subtype stability.Methods: Participants (n = 170) from two prospective cohorts were included: the Early PD Longitudinal Singapore (PALS) study and the National Neuroscience Institute Movement Disorders Database. Early PD patients were classified into tremor-dominant (TD), postural instability and gait difficulty (PIGD), and indeterminate subtypes according to the Movement Disorder Society's Unified PD Rating Scale (MDS-UPDRS) criteria and clinically evaluated for three consecutive years.Results: At baseline, 60.6% patients were TD, 12.4% patients were indeterminate, and 27.1% patients were PIGD subtypes (p < 0.05). After 3 years, only 62% of patients in TD and 50% of patients in PIGD subtypes remained stable. The mean levodopa equivalent daily dose (LEDD) was higher in the PIGD subtype (276.92 ± 232.91 mg; p = 0.01). Lower LEDD [p < 0.05, odds ratio (OR) 0.99, 95% confidence interval (CI): 0.98–0.99] and higher TD/PIGD ratios (p < 0.05, OR 1.77, 95% CI: 1.29–2.43) were independent predictors of stability of TD subtype with an area under the curve (AUC) of 0.787 (95%CI: 0.669–0.876), sensitivity = 57.8%, and specificity = 89.7%.Conclusion: Only 50–62% of PD motor subtypes as defined by MDS-UPDRS remained stable over 3 years. TD/PIGD ratio and baseline LEDD were independent predictors for TD subtype stability over 3 years.
Highlights
More than 6 million people suffer from Parkinson’s disease (PD) worldwide, and these numbers will continue to rise due to increasing life expectancy and aging [1, 2]
The clinical diagnosis was made by movement disorder specialists and adhered to the diagnostic criteria defined by the National Institute of Neurological Disorders and Stroke (NINDS) for PD [23]
A total of 170 idiopathic PD patients that comprised of 111 patients from the PD Longitudinal Singapore (PALS) cohort and 59 from the Database cohort were included in the study
Summary
More than 6 million people suffer from Parkinson’s disease (PD) worldwide, and these numbers will continue to rise due to increasing life expectancy and aging [1, 2]. Various classification schemes have merged NMS and motor features to classify PD subtypes [6,7,8]. PD patients show striking differences in the progression of the disease and disease-specific symptoms, which are ever-changing with disease progression. Due to this heterogeneity, PD patients have been grouped according to the dominance of the symptoms. PD patients have been grouped according to the dominance of the symptoms Recognition of these subgroups is important as it may define disease prognosis and impact clinical trial designs. Various classifications have been proposed to subtype Parkinson’s disease (PD) based on their motor phenotypes. The stability of these subtypes has not been properly evaluated
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