Expanded and Independent Spanish Validation of the MDS-Non Motor Rating Scale

[Background] The Movement Disorder Society-sponsored Non-motor Rating Scale (MDS-NMS) assess the severity and disability caused by non-motor symptoms (NMS) in Parkinson's disease (PD).
[Objective] This article encapsulates the formal process for completing this program and the data on the first officially approved non-English version of the MDS-NMS (Spanish).
[Methods] The MDS-NMS translation program involves four steps: translation and back-translation; cognitive pre-testing to ensure that raters and patients understand the scale and are comfortable with its content; field testing of the finalized version; analysis of the factor structure of the tested version against the original English language version for the nine domains that could be analyzed in a confirmatory factor analysis. To be designated an “Official MDS translation,” the confirmatory factor analysis Comparative Fit Index had to be ≥0.90.
[Results] The Spanish MDS-NMS was tested in 364 native-Spanish-speaking patients with PD from seven countries. For all subjects with fully computable data with all domains of the MDS-NMS (n = 349), the Comparative Fit Index was ≥0.90 for the nine eligible domains. Missing data were negligible and moderate floor effect (42.90%) was found for the Non-Motor Fluctuations subscale. Item homogeneity coefficient was adequate, and the correlation of the MDS-NMS domains with other measures for related constructs was acceptable (rs ≥ 0.50).
[Conclusions] The Spanish version of the MDS-NMS followed the IPMDS Translation Program protocol, reached the criterion to be designated as an Official Translation, and is now available on the MDS website.