Comparing postural instability and gait disorder and akinetic‐rigid subtyping of Parkinson disease and their stability over time

Abstract

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.

Consistency and Stability of Motor Subtype Classifications in Patients With de novo Parkinson’s Disease

“…As a result, the consistency between different motor subtypes is fair. In a previous study, the Jankovic and Schiess classifications were found to poorly overlap in 103 de novo PD patients (Erro et al, 2019). By contrast, in the present study of 283 patients with de novo PD, we found that the Jankovic classification is fairly consistent with the two motor subtype classifications of TD/mixed/AR.…”

“…Classification of PD subtypes is based on empirical clinical observations of prominent motor symptoms. At present, the recognized PD motor subtype classifications, including tremordominant/indeterminate/postural instability and gait difficulty (TD/indeterminate/PIGD) put forward by Jankovic and two classifications of the TD/mixed/akinetic-rigid (AR) classification system proposed by Schiess and Kang (Jankovic et al, 1990;Schiess et al, 2000;Kang et al, 2005), are widely used (Guan et al, 2017;Choi et al, 2018;Erro et al, 2019;Lian et al, 2019;Polychronis et al, 2019;Ren et al, 2020a,b). Although numerous additional subtypes based on data-driven approaches have been subsequently proposed (Graham and Sagar, 1999;van Rooden et al, 2010;Fereshtehnejad et al, 2015), the above three classifications occupy a dominant position in clinical practice and scientific research and have entered the conventional lexicon of clinicians.…”

“…However, the terminology used to describe PD motor subtypes has overlapping boundaries, which can result in confusion and lead to an extensively inaccurate literature (Kotagal, 2016). A recent study found that the consistency between the Jankovic classification and Schiess classification is poor (Erro et al, 2019). In addition, temporal instability of these two classifications in de novo PD patients has been reported (Simuni et al, 2016;Erro et al, 2019).…”

“…A recent study found that the consistency between the Jankovic classification and Schiess classification is poor (Erro et al, 2019). In addition, temporal instability of these two classifications in de novo PD patients has been reported (Simuni et al, 2016;Erro et al, 2019).…”

Comparison of Three Motor Subtype Classifications in de novo Parkinson's Disease Patients

“…Nevertheless, the sample size of the study was sufficient for analysis. Second, the motor symptoms and nonmotor abnormalities of de novo PD patients are generally mild, and a certain percentage of de novo PD patients show great variability in these motor subtype classifications (35,36). Future studies can compare the clinical characteristics of different motor subtypes in the late stages of the disease.…”