Pilot Study of the International Parkinson and Movement Disorder Society-sponsored Non-motor Rating Scale (MDS-NMS)

Background Non-motor symptoms (NMS) are integral to Parkinson's disease (PD) and have a detrimental effect on patients and their caregivers. Clinical quantification has been aided by the development of comprehensive assessments such as the Non-Motor Symptoms Questionnaire (NMSQuest) and Scale (NMSS). The NMSS has been widely used in clinical studies and trials; however, since its validation in 2007, our understanding of NMS has changed substantially. With the support of the International Parkinson and Movement Disorder Society (IPMDS), after a detailed peer review an initiative to develop an updated version of NMSS, the MDS-NMS was launched in 2015. Objective This paper encapsulates the data from the pre-validation phases carried out under the auspices of the IPMDS Non-Motor PD Study Group. Methods Item selection and wording (formatted as a rater-based tool) were based on the NMSS, literature review, and expert consensus. Neurologists, PD patients, and healthy controls were included in the cognitive pretesting and administration of the preliminary version of the MDS-NMS. Primary data on acceptability and reliability were obtained. Results The pilot study, carried out in English in the United Kingdom and the United States, demonstrated that the preliminary version of the MDS-NMS was comprehensive, understandable, and appropriate. Data quality was excellent; moderate floor effect was present in patients for most MDS-MNS domains, with some components showing weak internal consistency. The results led to additional instrument modifications. Conclusion Qualitative and quantitative research results have led to an updated NMSS, the definitive version of the MDS-NMS, which is currently being validated.