Non-motor symptoms in PD evaluated during pharmacological ON state by a new tool: The NoMoS-ON scale. Is always the "ON" state beneficial?

Objectives: To evaluate non-motor symptoms (NMS) occurring during ON pharmacological state and validate a new questionnaire, the Non-motor symptoms-ON scale (NoMoS-ON), exploring ON NMS in Parkinson's disease (PD). Material and methods: Patients with PD were evaluated by a new questionnaire, the NoMoS-ON scale, evaluating 17 items related to the main symptoms experienced during the ON state. PD patients who experienced at least one symptom in ON were defined ON-NMS+. Internal consistency and test-retest reliability of NoMoS-ON scale were also assessed. Results: One-hundred and thirty-seven PD patients were consecutively enrolled (79 men and 58 women, age 69.4 ± 9.5 years (mean ± SD)). Seventy-seven patients were ON-NMS+ (56.6 %). PD patients with short disease duration (<7 years) showed the presence of unpleasant NMS: "sleepiness", "light-headedness", "nausea/vomiting". PD patients with longer disease duration experienced pleasant non-motor features including "feel lot of energy", "feel physical well-being". ON-NMS+ were also associated with female gender (OR 2.81, 95%CI 1.37-5.77, p-value 0.005) and with motor fluctuations (OR 2.41, 95%CI 1.20-4.83, p-value 0.013). Cronbach's alpha was 0.61 and 5 items had adequate item-to-total correlations (r ≥ 0.40). Test-retest reliability was acceptable (intraclass correlation coefficient, ICC = 0.77). Conclusions: The NoMoS-ON scale is a valid, reproducible and reliable questionnaire capturing the ON NMS in PD. PD patients with disease duration shorter than 7 years showed the presence of unpleasant NMS whereas those with longer disease duration experienced pleasant non-motor features. This could help the physician in the therapy management of PD patients in different phases of their disease.