Age, Gender, Comorbidity, and the MDS-UPDRS: Results from a Population-Based Study

Abstract

Background: Understanding sources of variation in International Parkinson and Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) scores is essential for planning clinical trials in Parkinson's disease and interpreting studies of mild parkinsonian signs. Methods: We describe the characteristics of the MDS-UPDRS in a population-based sample of individuals without parkinsonism. Multiple linear regression and Spearman's rank correlation coefficients were used to examine potential associations. Results: Among 194 consecutive individuals without parkinsonism, the mean total MDS-UPDRS score was 12.5 (SD 9.8). Sixty-nine percent (134/193) had motor examination (Part III) scores of 2 or more, 16% (30/194) had scores of 10 or more. Female sex, arthritis or spondylosis, diabetes mellitus, and essential tremor were found to be associated with statistically significant increases in MDS-UPDRS Part III scores. For every 10-year increase in age, the Part III score was greater on average by 2.2 (1.5-2.8). Conclusions: Elevated MDS-UPDRS scores are common in the general population. The overall burden of motor signs of parkinsonism is especially high in older age groups, in women, and in those with particular comorbidities. Whether this represents evidence of a subclinical neurodegenerative process or the effect of comorbid conditions requires further examination.

Non-motor symptoms and quality of life in subjects with mild parkinsonian signs

“…The degree of motor impairment was similar between this group and the MPS group. 28 Unlike here, subjects with motor abnormalities due to orthopedic problems were not analyzed as a separate group, which may at least in part explain the different gender distribution. 34 An interesting aspect is the gender distribution in the different subgroups.…”

“…According to the current pathophysiological concept of ascending alpha-synuclein pathology in PD, 3,4 such non-motor "brainstem" symptoms may occur prior to the motor manifestation of PD. 28 A substantial proportion of subjects with MPS of up to 40%, however, revert to a normal motor state after 1-2 years. 26 In contrast, cortical 30 This high conversion rate clearly exceeds the overall PD risk of individuals >60 years of 2%, supporting the concept of prodromal PD in a subset of individuals with MPS.…”

Differential item functioning in the Unified Dyskinesia Rating Scale (UDysRS)

“…For the age‐based DIF analyses, we chose 3 age groups (27‐51, 52‐75, and 76‐93) to result in at least 280 cases in each age group. We chose this age divisions to reflect our age ranges (27‐93), and they are similar to other reports examining age divisions in PD . Based on years of education, we divided the sample into three groups (<7, 7‐12, > 12), which resulted in 680 cases in each education group .…”

Challenges in detecting disease modification in Parkinson's disease clinical trials

“…The first appearance of motor dysfunction as detected by the MDS-UPDRS may indicate appearance of disease onset (and has been used as an endpoint in premanifest Huntington's disease trials), however mild elevation in MDS-UPDRS Part III scores (2-10) can occur in the general population and increases with age [27], making interpretation difficult. Conversion to overt PD could in theory be used as an endpoint.…”