Inter-rater reliability of hand motor function assessment in Parkinson's disease: Impact of clinician training.

Medication adjustments in Parkinson's disease (PD) are driven by patient subjective report and clinicians' rating of motor feature severity (such as bradykinesia and tremor). Objective: As patients may be seen by different clinicians at different visits, this study aims to determine the inter-rater reliability of upper limb motor function assessment among clinicians treating people with PD (PwPD). Methods: PwPD performed six standardised hand movements from the Movement Disorder Society's Unified Parkinson's Disease Rating Scale (MDS-UPDRS), while two cameras simultaneously recorded. Eight clinicians independently rated tremor and bradykinesia severity using a visual analogue scale. We compared intraclass correlation coefficient (ICC) before and after a training/calibration session where high-variance participant videos were reviewed and MDS-UPDRS instructions discussed. Results: In the first round, poor agreement was observed for most hand movements, with best agreement for resting tremor (ICC 0.66 bilaterally; right hand 95 % CI 0.50-0.82; left hand: 0.50-0.81). Postural tremor (left hand) had poor agreement (ICC 0.14; 95 % CI 0.04-0.33), as did wrist pronation-supination (right hand ICC 0.34; 95 % CI 0.19-0.56). In post-training rating exercises, agreements improved, especially for the right hand. Best agreement was observed for hand open-close ratings in the left hand (ICC 0.82, 95 % CI 0.64-0.94) and resting tremor in the right hand (ICC 0.92, 95 % CI 0.83-0.98). Discrimination between right and left hand features by raters also improved, except in resting tremor (disimprovement) and wrist pronation-supination (no change). Conclusions: Clinicians vary in rating video-recorded PD upper limb motor features, especially bradykinesia, but this can be improved somewhat with training.