Content validity of a sleep numerical rating scale and a sleep diary in adults and adolescents with moderate-to-severe atopic dermatitis

BACKGROUND: The intense itching associated with atopic dermatitis (AD) often causes patients to experience severe sleep disturbance. Here, we describe the results of a two-phase concept elicitation and cognitive interview study to establish the content validity of a sleep disturbance numerical rating scale (SD NRS) and a Consensus Sleep Diary adapted for adults and adolescents with moderate-to-severe AD (CSD-AD©). RESULTS: In phase I, a concept elicitation conducted in 20 adults and 10 adolescents with moderate-to-severe AD revealed that the following sleep-related issues were important and relevant: nighttime awakening (87%), trouble falling asleep (73%), feeling unrested (53%), daytime fatigue or sleepiness (53%), and feeling as if they did not get enough sleep (33%). The frequency and extent of sleep disturbance varied substantially from day to day due to varying degrees of itching and flares, medication use, and changes in the weather. All participants understood the SD NRS question, with most finding it easy or very easy to understand (100% of adults and 90% of adolescents) and most understanding the anchors as intended (95% of adults, and 100% of adolescents). Most participants (94% of adults, and 90% of adolescents) indicated that they would consider a one- or two-point change meaningful on the SD NRS. The CSD-AD© was revised based on participant feedback, and tested during phase II in a convenience sample of six adults and four adolescents from phase I. The changes made to the CSD-AD© were confirmed to be relevant and understandable. All patients were able to provide an answer to each item in the CSD-AD©, and most were able to estimate the duration of nighttime awakenings, daytime naps, and dozing. CONCLUSIONS: The study supported the content validity of the SD NRS and CSD-AD© in adults and adolescents with moderate-to-severe AD. It also emphasized the importance of using these instruments daily when assessing the benefit of a new treatment on sleep quality in this population.