Rating scales and questionnaires for assessment of sleep disorders in Parkinson's disease: what they inform about?

Sleep disorders are very prevalent in Parkinson's disease (PD) and include a diversity of disturbances. Rating scales and questionnaires are widely used to assess the presence and severity of the sleep disorders. The objective is to review rating scales and questionnaires used for assessment of sleep disorders in PD. To this purpose, a description and update of the sleep scales reviewed by the ad hoc Movement Disorder Society task force (MDS-TF) and other sleep disorder assessments was performed. Two specific (Parkinson's Disease Sleep Scale and Scales for Outcomes in PD Sleep) and two generic scales (Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale) were "Recommended'' by the MDS-TF as they were used in PD patients, by researchers others than their developers and properly validated. Two other generic scales (Inappropriate Sleep Composite Score and Stanford Sleepiness Scale), "Suggested'' due to incomplete validation, are also reviewed. Other instruments included in this review are three comprehensive PD-specific instruments for assessing multiple domains in addition to sleep problems (e. g., Non-Motor Symptoms Questionnaire, Non-Motor Symptoms Scale, MDS-UPDRS), and three generic instruments focused on particular disturbances (e. g., International Restless Legs Syndrome Study Group Rating Scale, REM behavioral disorders questionnaires), although these latter lack formal validation in PD populations. The "Recommended'' instruments cover satisfactorily the needs for screening and evaluation of the nocturnal sleep disorders and daytime sleepiness in PD patients. It would be convenient to validate or complete the validation in PD populations of those instruments that cannot be recommended due to the lack of information on their clinimetric attributes.