Psychometric properties of the Croatian version of the Non-motor Symptoms Scale in Parkinson’s disease

Objectives: The objective was to evaluate the psychometric properties of the Croatian version of the Non-Motor Symptoms Scale (NMSS), a tool to assess non-motor symptoms (NMSs) in Parkinson’s disease (PD). Methods: A cross-cultural adaptation of the NMSS into Croatian and a psychometric analysis of the translated version of the NMSS was carried out in PD patients. NMSS includes nine domains: cardiovascular, sleep/fatigue, mood/cognition, perceptual problems/hallucinations, attention/memory, gastrointestinal tract, urinary, sexual function and miscellaneous. The quality of data was descriptively analysed, and Cronbach’s alpha coefficient assessed internal consistency. Pearson correlations were performed on the nine domains. The level of significance was set to p<0.05. Results: 76 PD patients were assessed (mean age 68.4±9.6 years; 45% women; mean length of disease 8.7±4.6 years). Mean NMSS score was 110.68±58.76, where the more common NMSs in PD patients were related to the following domains: mood/cognition (22.86 %), sleep/fatigue (19.74 %), sexual function (13.65 %) and urinary (11.58 %). Cronbach’s alpha for the NMSS total score was 0.92 (range for domains: 0.48-0.96). Total NMSS score was highly correlated with each of the nine domains (Pearson correlation range: 0.45-0.82). Conclusions: The Croatian version of NMSS can be considered a comprehensive and helpful measure for NMSs in Croatian-speaking PD patients.