Objective: To assess the level of agreement between the MDS-UPDRS-III in sitting and supine position.

Background: The clinical effect during stereotactic neurosurgery for Parkinson’s disease (PD) is routinely assessed supinely using the Movement Disorder Society Unified PD Rating Scale part III (MDS-UPDRS-III) [1]. However, this clinical scale was originally validated in sitting position. As its use in supine position has not been validated yet, this study aims to assess the agreement between the MDS-UPDRS-III in sitting and supine position.

Method: Twenty-three PD-patients underwent MDS-UPDRS-III assessment in sitting and supine position, while accelerometric measurements were performed at the index fingers. Video recordings of the assessments were evaluated by two certified raters. Agreement between MDS-UPDRS-III scores in sitting and supine position was quantified by Cohen’s kappa coefficient. Regression was used to model the relationship between MDS-UPDRS-III tremor scores and accelerometric amplitudes for both positions.

Results: A fair to near-perfect agreement was found between MDS-UPDRS-III scores of the individual items in sitting versus supine position; κ ranged from 0.300 to 0.810 (p<0.001). Correction for multiple comparisons was not applied. All MDS-UDPRS-III tests combined produced a substantial agreement with a relatively narrow 95% confidence interval (κ=0.613; 95%CI: 0.556, 0.670; p<0.001). Inter-rater reliability was slight to substantial in both positions; κ ranged from 0.111 to 0.786 (p<0.001). The lowest inter-rater reliabilities were found for the speech and bradykinetic items. The overall inter-rater reliability was slightly better in sitting position than in supine position. A strong association between MDS-UPDRS-III tremor scores and (log-transformed) accelerometric amplitude was observed in both sitting and supine positions (R²>0.712; p<0.001).

Conclusion: This study supports the supine application of the MDS-UPDRS-III, although some items (e.g. speech and bradykinesia) might be further examined in order to maintain the scale’s validity. In addition, the MDS-UPDRS-III in general remains sensitive to inter-rater variability, due to the subjective nature of the MDS-UPDRS.

References: 1. Goetz, C.G.; Fahn, S.; Martinez-Martin, P.; Poewe, W.; Sampaio, C.; Stebbins, G.T.; Stern, M.B.; Tilley, B.C.; Dodel, R.; Dubois, B.; et al. The MDS-Sponsored Revision of the Unified Parkinson’s Disease Rating Scale. Available online: www.movementdisorders.org (accessed on 16 January 2022).

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MDS Abstracts - https://www.mdsabstracts.org/abstract/peroperative-use-of-the-mds-updrs-motor-section-agreement-between-sitting-and-supine-position/