0754 Patient Experience of Fatigue and Assessment in Narcolepsy: A Cross-Sectional Study

Abstract Introduction Fatigue and excessive daytime sleepiness (EDS) are symptoms of narcolepsy and are often described as overlapping. Among patients with narcolepsy, EDS is commonly reported with and without fatigue, and vice versa, suggesting that these symptoms are indeed distinct. However, there is no validated patient-reported outcome measure (PROM) designed specifically to evaluate fatigue in patients with narcolepsy. The aims of this study were to examine the relationship between fatigue and EDS in narcolepsy, and to evaluate the performance of a PROM to assess fatigue in narcolepsy. Methods This was a cross-sectional, mixed-methods study in adults (aged ≥18 years) with narcolepsy (type 1 or 2) who reported fatigue ≥3 days per week. Patients completed two 45-minute qualitative interviews to 1) describe the experience of fatigue and EDS in the context of narcolepsy, and 2) facilitate evaluation of a fatigue-specific PROM (Patient-Reported Outcomes Measurement Information System Fatigue Short Form 7a [PROMIS-Fatigue SF 7a]). Results Of the 117 patients with narcolepsy screened, 26 (22.2%) participated in the interviews (mean [SD] age, 39.5 [11.3] years; 73% were female). Common responses (% of patients) to describe fatigue in narcolepsy were lack of energy (92%), cognitive difficulties (81%), physical sensations (eg, heaviness [69%]), and emotional effects (eg, grumpy [61%]), whereas EDS was generally described in terms of an overwhelming, urgent, and sometimes involuntary need to sleep. Overall, 80% of patients described fatigue and daytime sleepiness as distinct symptoms. The qualitative analysis informed the development of a conceptual model for fatigue in narcolepsy that consisted of physical, cognitive, emotional, and social domains. All patients felt that the content in the PROMIS-Fatigue SF 7a was relevant to their experience of fatigue in narcolepsy. More than half of the patients felt that PROMIS-Fatigue SF 7a items pertaining to cognitive function and impacts at work best captured their experience with fatigue. Conclusion Fatigue is a distinct symptom of narcolepsy and can be differentiated from EDS. The PROMIS-Fatigue SF 7a is a fit-for-purpose PROM to assess fatigue in future clinical trials. Support (if any) Harmony Biosciences