Validation of the Italian version of the Non Motor Symptoms Scale for Parkinson's disease

Abstract

ObjectiveTo validate the adapted Italian version of the Non-Motor Symptoms Scale (NMSS), a tool to assess non-motor symptoms (NMS) in Parkinson's disease (PD). MethodsA cross cultural adaptation of the NMSS into Italian and a psychometric analysis of the translated version of the NMSS was carried out in patients with PD from two university centres–affiliated hospitals. The quality of data and the acceptability, reliability and construct validity of NMSS were analyzed. The following standard scales were also applied: Hoehn and Yahr staging, Unified Parkinson's Disease Rating Scale (UPDRS) part III, Montreal Cognitive Assessment, Beck Depression Inventory, Neuropsychiatric Inventory, Epworth Sleepiness Scale, Autonomic Scale for Outcomes in Parkinson's disease-Motor, Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale part I and Modified Cumulative Illness Rating Scale (CIRS). Levodopa equivalent daily dose (LEDD) was calculated. ResultsSeventy-one patients with PD were assessed (mean age years 69.8 ± 9.6 SD; 31% women; mean length of disease 6.3 ± 4.6 years; H&Y median: 2). Mean NMSS was 39.76 (SD 31.9; skewness 0.95). The total score of NMSS was free of floor or ceiling effects and showed a satisfactory reliability (Cronbach's alpha coefficient on total score was 0.72 [range for domains: 0.64–0.73], SEM value was 3.88 [½ SD = 31.90]). Significant positive correlations were found among total NMSS and other NMS standard tests, but no significant correlation appeared with UPDRS part III, CIRS and LEDD. ConclusionsThe Italian NMSS is a comprehensive and helpful measure for NMS in native Italian patients with PD.