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.
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