Development of the Pediatric Restless Legs Syndrome Severity Scale (P-RLS-SS)©: A patient-reported outcome measure of pediatric RLS symptoms and impact

Objective: To develop a questionnaire to measure Pediatric Restless Legs Syndrome (P-RLS) symptoms and impact for use in clinical research. Methods: Questionnaire items were developed based on open-ended, qualitative interviews of 33 children and adolescents diagnosed with definite RLS (ages 6-17 years) and their parents. The draft questionnaire was then tested through cognitive debriefing interviews with 21 of the same children/adolescents and 15 of their parents. This involved the children and parents answering the draft items and then interviewing them about the child's ability to understand and interpret the questionnaire. Expert clinicians provided clinical guidance throughout. Results: Draft severity questions were generated to measure the four-symptom and four-impact domains identified from the concept elicitation interviews: RLS sensations, move/rub due to RLS, relief from move/rub, pain, and impact of RLS on sleep, awake activities, emotions, and tiredness. RLS descriptions, symptoms, and impact were compared between those who had comorbid attention-deficit/hyperactivity disorder and those who did not. Revisions to several questions were made based on the cognitive debriefing interviews and expert clinician review, resulting in a severity scale with 17 morning and 24 evening items. Caution regarding self-administration in children ages 6-8 years is recommended. To complement the child/adolescent measures, a separate parent questionnaire was also developed. Conclusions: The P-RLS-SS was constructed based on detailed input from children and adolescents with RLS, their parents, and clinical experts, thus providing a scale with strong content validity that is intended to be comprehensive, clinically relevant, and important to patients. Validation of this scale is recommended.