Objective: To revise the Non-Motor Sumptom Scale (NMSS) and develop a new up to date version, the MDS-NMS, a project commissioned by the International Parkinson and Movement Disorder Society (IPMDS). We report data from phases 1 (preliminary version) and 2 (pilot study).

Background: The NMSS was developed in 2006 and remains the only composite scale to assess the burden of NMS in Parkinson’s disease (PD) and needs updating.

Methods: Phase 1: A preliminary version of MDS-NMS (pvMDS-NMS) was developed including 15 domains with 63 items, each one scoring for frequency (0 to 4), severity (0 to 4), and a total score (frequency x severity; 0 to 16). Additionally, the scale includes an optional section for evaluating non-motor fluctuations (NMF) in 7 domains. Phase 2: A pilot study (UK and USA) was performed in 69 non demented PD patients and 19 healthy controls by 52 experienced evaluating neurologists using the neurologist-based pvMDS-NMS and questionnaires about the MDS-NMS for neurologists, patients, and controls. Statistical analysis addressed data quality, missing values, scores distribution, and preliminary reliability.

Results: The pvMDS-NMS scores were fully computable in 95.64%. Total pvMDS-NMS mean score (±SD) was 91.6±100.5 (range: 10–491). All domains, except Sleep and Wakefulness (7.2%) showed floor effect >15% (22.1–79.7%), but none had relevant ceiling effect (1.4–4.5%). Cronbach’s alpha index was satisfactory for 9/15 domains. Inter-item and Item-total correlations were globally satisfactory, and the item homogeneity index (standard value, >0.30) was satisfactory for most domains, except for Impulse control and related disorders, Other Neuropsychiatric symptoms, and Other Symptoms. The optional NMF section was completed by 71%, with similar findings in score distribution to the main pvMDs-NMS. In controls there were no missing values and the total pvMDS-NMS score (mean±SD) was 28.5±12.0 (range: 0-151). Over 80% of the neurologists opined that the scale was relevant, useful, and comprehensive, and < 5% reported length, wording, or scoring issues. The corresponding proportions for patients were >86% and <15%, respectively.

Conclusions: pvMDS-NMS showed satisfactory basic clinimetric attributes of the scale while some items and domains performed poorly. The definitive version of the MDS-NMS is now to be validated.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-international-parkinson-and-movement-disorder-society-non-motor-rating-scale-mds-nms-results-from-the-cognitive-pre-testing-and-phases-1-and-2-of-an-international-validation/