Brief Clinical Rating Scales Should Not Be Overlooked

This is the authors' abstract. We don't add key points for this paper.

Piot and colleagues1 are to be highly commended for developing a brief rating scale for progressive supranuclear palsy (PSP). The PSP Clinical Deficits Scale (PSP-CDS) comprises seven domains, each scored 0–3. Clinimetrically sound and taking ≈5 minutes to complete, the scale is envisaged to be useful in clinical care and research, including clinical trials. By contrast, the current gold standard PSP Rating Scale, introduced in 2007, consists of 28 items, and takes ≈3× longer to administer.1 In Parkinson's disease (PD), the Movement Disorder Society Unified PD Rating Scale (MDS-UPDRS) is widely considered the gold standard. Encompassing 65 items, it has undergone extensive clinimetric testing and demonstrated strong outcomes. It also includes a broader range of nonmotor symptoms compared with its predecessor (the UPDRS); administration takes ≈30 minutes. The time-consuming nature of this and other comprehensive assessments, however, raises several issues.2 The first concerns sampling bias in research. Severely disabled individuals are often excluded because of inability to complete more laborious evaluations. Such assessments also increase the likelihood of patient unwillingness to participate, in some cases influenced by low mood, anxiety, or apathy (all common in PD). Data on nonparticipation are infrequently reported, so it is hard to know the true extent of this problem. Recent statistics offer a glimpse; for example, a survey of 103 centers conducting research in PD genetics found that only two-thirds reported having UPDRS/MDS-UPDRS data for "at least a subset" of patients.3 Unavailability of personnel and constraints on clinician time are critical factors further limiting participation, especially in under-resourced settings.4 A lack of ethno-geographical diversity in studies has been increasingly highlighted as a major gap in medical research. PD is not exempt; a global listing of cohort studies showed that <10% were in Asia Pacific countries (representing >50% of the global patient population!).4 This should raise alarm regarding the (un)representativeness of our current research enterprise—and the inequities this could entail. In contrast, in well-resourced settings, it could be anticipated that the task of administering longer scales will often fall onto juniors, potentially affecting interrater reliability of scoring. We recently captured "real-world" data on global PD severity in 828 patients within a busy clinic practice, using the Clinical Impression of Severity Index for PD.5 Akin to the PSP-CDS, several core disease domains (motor signs, disability, motor complications, cognitive status) are rated on a 0–6 Likert scale, emphasizing functional impact. Ratings, typically taking ≤10 minutes, were incorporated into routine consultations, facilitating participation of patients spanning a wide demographic and disease spectrum (Fig. 1A). We reproduced the expected (mostly high) correlations with established measures5 (Fig. 1B–D). The data also enabled broad comparisons of the clinical severity of selected monogenic PD cases6 (Fig. 1E–H). Undoubtedly, comprehensive rating scales will continue to play an important role given the multifaceted nature of PD, because they capture more information, including nonmotor features that frequently cause significant impairment to the quality of life of people living with PD. At the same time, we should not overlook the usefulness of simple, but still valid and reliable, instruments to rate disease severity, which can be used in appropriate circumstances to improve care and bolster research. The study was approved by the University of Malaya Medical Centre Medical Research Ethics Committee (ID numbers 732.5 and 20191010–7917) and conducted ethically in accordance with the World Medical Association Declaration of Helsinki. Written informed consent was obtained from all subjects. S.-Y.L. and A.H.T. are supported by the University of Malaya Parkinson's Disease and Movement Disorder Research Program (PV035-2017). We gratefully acknowledge the PD gene panel analysis provided by Centogene, Rostock, Germany, as part of a collaboration with Profs. Christine Klein, Katja Lohmann, Arndt Rolfs, and Peter Bauer. Research Project: conception (S.-Y.L.), organization (S.-Y.L., A.H.T.), and execution (all authors). Statistical Analysis: design (S.-Y.L.), execution (K.B.L.), and review and critique (S.-Y.L.). Manuscript: writing of the first draft (S.-Y.L.), and review and critique (all authors).