Validation of the non-motor symptoms questionnaire (NMS-Quest)

Abstract

Background Although non-motor manifestations of Parkinson’s disease are common and can cause severe disability, they are often under-recognized, leading to missed treatment opportunities. Screening tools for non-motor symptoms are urgently needed. Recently a 30–item screening Non Motor Symptoms Questionnaire was developed. Although some psychometric properties have been evaluated, sensitivity and specificity of the questionnaire have not been systematically assessed. Methods Parkinson patients completed Non Motor Symptoms Questionnaire, then underwent a gold-standard clinical evaluation of non-motor symptoms and signs that included extensive standardized questionnaires, cognitive/behavioural assessment, and neurological examination to determine whether each manifestation was present or absent. The sensitivity and specificity of each non-motor symptom, in relation to the gold-standard were estimated. Results For the 70 participants, the mean age was 66.7+/−9.3, 64% were men, and disease duration was 3.8+/−2.8 years. From the gold-standard evaluation, the prevalence of non-motor manifestations ranged from 8.7% (hallucinations) to 78.3% (nocturia). The mean sensitivity of all Non Motor Symptoms was 63.4%. This varied considerably among different manifestations, ranging from 24% (sleepiness, hyposmia) to 100% (diplopia). By restricting analysis to clinically significant non-motor problems (i.e. those serious enough to warrant treatment), the mean sensitivity increased to 71.8%. The specificity for most items was high, with an overall mean specificity of 88.5%. Conclusions For many non-motor manifestations Non Motor Symptoms Questionnaire is an effective screen; however, for manifestations such as somnolence, olfactory loss and apathy, sensitivity is suboptimal. Overall, this questionnaire can be a useful clinical tool for screening non-motor problems in an office setting.