Background and purpose: Parkinson disease (PD) patients are classically classified according to two alternative motor subtyping methods: (i) tremor-dominant versus postural instability and gait disorder; (ii) tremor-dominant versus akinetic-rigid. The degree of overlap between the two classification systems at diagnosis of PD and their temporal stability, as well as the correspondence between the two systems, were examined over a follow-up period of 4 years.
Methods: Newly diagnosed, untreated PD patients were classified as tremor-dominant versus postural instability and gait disorder and tremor-dominant versus akinetic-rigid at baseline and after 2 and 4 years.
Results: There was a poor overlap between the two classification systems at any time point and baseline subtype status could not predict 4-year subtype membership. In fact, about half of our cohort shifted category during the first 2 years, regardless of the classification scheme adopted. A lower rate of shift was observed from 2- to 4-year follow-up.
Conclusions: The two classical motor subtyping methods of PD poorly overlap, which implies that a patient can be categorized as tremor-dominant in one classification system but not in the other. Moreover, their temporal instability undermines their prognostic value in the early stage of PD.
Keywords: de novo; cluster; heterogeneity; postural instability and gait disorder; untreated.
© 2019 EAN.