Abstract
Background: The Unified Parkinson's Disease Rating Scale (UPDRS) is the gold standard for assessing Parkinsonian symptoms, yet objective outcome measures are needed to complement the UPDRS in research and clinical practice. Objective: This study aimed to investigate the relationship between performance on the Grooved Pegboard Test (GP) and clinical assessment of Parkinson's motor symptoms with the UPDRS. Methods: A large sample of individuals with Parkinson's disease (n = 191) were assessed with the GP and UPDRS motor section. The GP was separated into a place (more representative of visuospatial accuracy) and remove phase (general representation of motor speed and bradykinesia). Both tests were completed at peak anti-parkinsonian medication levels, and UPDRS subscores were calculated to represent upper-limb control, rigidity, bradykinesia, and tremor. A subsequent correlation analysis was completed. Results: The strongest relationships were between the GP place phase (both limbs) and total UPDRS motor score (affected: r = 0.604, less-affected: r = 0.587), upper-limb control (affected: r = 0.367, less-affected: r = 0.426), rigidity (affected: r = 0.479, less-affected: r = 0.457) and body bradykinesia (affected: r = 0.375, less-affected: r = 0.438). The GP remove phase had weak positive relationships with total UPDRS scores (affected: r = 0.31, less-affected r = 0.31) and body bradykinesia (r = 0.31). Conclusions: Clinical assessment of upper-limb control, rigidity and bradykinesia are well represented by the GP place phase. Interestingly, it appeared that GP performance of the more affected limb may be more representative of motor severity in the early stages of disease, while more research is needed to understand the utility of the GP in the advanced stages of disease.