Objective: To analyze the acceptability and reliability of the Movement Disorders Society – Non Motor Rating Scale (MDS-NMS).

Background: Parkinson’s disease (PD) is a chronic and neurodegenerative disease with motor and non-motor manifestations. The newly developed MDS-NMS has been designed for a global and comprehensive assessment of NMS. The analysis of the psychometric properties of acceptability and reliability provides information on the quality of the MDS-NMS scores, including assessment of freedom from random error.

Method: A sample of 402 PD patients was recruited from movement disorders clinics in UK and US for a multi-center, cross-sectional study on MDS-NMS validation. Data on socio-demographic characteristics and PD treatment was gathered. The MDS-NMS, composed by 13 domains and a subscale on non-motor fluctuations (NMFs), was administered together with other PD-specific rating scales. Data quality, acceptability and reliability (internal consistency, test-retest in 123 patients, and inter-rater in 164) were calculated.

Results: The sample (62.2% men) had a mean age of 67.42 years old (SD: 9.96), a mean PD duration of 8.2 years (SD: 5.93) and was mainly in HY stage 2 (54.5%). Mean MDS-NMS total score was 79.33 (SD: 65.87; range: 0-334), with 7.2% missing data and no floor or ceiling effects. All MDS-NMS domains presented floor but not ceiling effects. Mean NMFs subscale total score was 6.87 (SD: 13.17; range: 0-88) in the full sample and 16.87 (SD: 16.06; range: 1-88) in patients with some non-motor fluctuations. Missing data for the NMFs subscale was 1.2% and did not show floor or ceiling effects. Cronbach’s alpha for domains ranged from 0.32 (E. Impulse control & related disorders) to 0.86 (A. Depression), and was 0.66 for MDS-NMS total score. Item-total correlation was low for some items. NMFs subscale Cronbach’s alpha was 0.84 and item-total correlation ranged from 0.39-0.71. Test-retest agreement was higher than 95% for most MDS-NMS items, with kappa=0.26-0.86 for individual items and ICC=0.50-0.85 for domains. Agreement was >95% for most NMFs items, with kappa=0.48-0.68 and ICC=0.76. Inter-rater agreement was >99% for all but one MDS-NMS items, with kappa=0.89-1.0 for items and ICC=0.97-1.0. For the NMFs subscale agreement was >99%, kappa=0.90-0.99 and ICC=0.99.

Conclusion: As a whole, data quality, acceptability and reliability of the MDS-NMS were satisfactory.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/data-quality-acceptability-and-reliability-of-the-movement-disorders-society-non-motor-rating-scale-mds-nms/