Evaluation of an Arabic version of the non-motor symptoms scale in Parkinson's disease

Abstract

Non-motor symptoms (NMS) of Parkinson Disease (PD) are common and can cause severe disability. They are often under-recognized and remain untreated. Tools to evaluate these symptoms in Arabic-speaking patients are still lacking. The objective of this study was to evaluate an Arabic version of the non-motor symptoms scale (NMSS) of PD as an instrument for measuring NMS in Arabic-speaking patients. Sixty-two PD patients clustered around Hoehn & Yahr Stages 2-3 were evaluated by the Arabic version of NMSS. They also underwent a battery of standard psychometric assessment measures that included the scales for outcomes of Parkinson's disease-autonomic (SCOPA-AUT), the Pittsburgh sleep quality index (PSQI), the Beck depression inventory, the geriatric depression scale (GDS), the mini-mental state examination (MMSE), the visual analogical scale for pain(VAS) and the neuro-psychiatric inventory (NPI). The metric properties of the NMSS were studied as well as its correlation with other standard tests evaluating NMS. The mean NMSS score was 82 ± 56 (skewness 0.88). There were highly significant correlations between the NMSS and the SCOPA-AUT as well as the NMSS and PSQI scores. Significant positive correlations between NMSS and GDS, BECK and VAS were also observed. The sleep/fatigue domain significantly correlated with the PSQI, the cardiovascular/urinary/sexual function/gastrointestinal domains significantly correlated with the SCOPA-AUT, the mood/cognition domain significantly correlated with the GDS and BECK findings. The mean Cronbach's alpha coefficient was 0.87, showing a satisfactory internal consistency. The Arabic version of NMSS can be considered a comprehensive and reliable measure for non-motor symptoms in Arabic-speaking PD patients.

Keywords: Non-motor symptoms scale; Parkinson’s disease; Reliability; Validation.