Evaluation of nocturnal hypokinesia in Parkinson’s disease using a novel patient/proxy questionnaire and correlations with objective monitoring

Abstract Background Nocturnal hypokinesia is a decreased ability to perform sufficient axial rotation and/or trunk flexion to turn in or get out of bed. Currently, there are no validated questionnaires specifically to assess nocturnal hypokinesia in PD patients. Objective To develop and validate a questionnaire to assess PD patients’ problems associated with turning or getting out of bed. Methods The nocturnal hypokinesia questionnaire (NHQ) consists of 10 items, completed independently by patients and their caregivers. For validation, 76 patient-caregiver pairs completed the questionnaire and validity, agreement levels, and internal consistency assessed. In addition, 76 healthy couples served as controls. The NHQ and Modified Parkinson's Disease Sleep Scale (PDSS-2) were compared and 25 random patients-caregiver pairs were also assessed with objective night-time monitoring. Results Patient and caregiver scores showed a high level of agreement (Intra-class correlation: 0.84) with high internal consistency (KR-20 coefficient of 0.73 for patients and 0.69 for caregivers). No significant difference between the mean total NHQ scores as rated by patients and caregivers was observed. Mean NHQ scores from patients and caregivers were significantly higher than healthy controls ( p p  = 0.004), and with objective monitoring (Number of turns: r = −0.41, p  = 0.04, Degree of turn: r = −0.44, p  = 0.02). Conclusion The NHQ is a reliable instrument to identify symptoms of nocturnal hypokinesia amongst PD patients. Strong patient-caregiver agreement supports the use of proxy evaluation by caregivers when patient's information is unobtainable.