Ecological Momentary Assessment of Fatigue in Adults with Cerebral Palsy: Feasibility, Reliability, and Validity

Background/Objectives: Fatigue is a common symptom in adults with cerebral palsy (CP), characterized by fluctuations across the day. This pilot study aimed to evaluate the feasibility, reliability, and validity of ecological momentary assessment (EMA) for capturing these temporal dynamics in adults with CP. Methods: Ten adults with CP (60% female, mean age = 44 years, Gross Motor Function Classification System levels I-III) and eight typically developed controls (62% female, mean age = 39 years) completed a 20-item EMA survey ten times daily for seven days using the SEMA³ smartphone application. Feasibility was evaluated through retention rates, response rates, and qualitative interviews. Intraindividual variability, within-person reliability, measurement reactivity, and convergent validity with the Fatigue Severity Scale (FSS) were examined using mixed-effects regression and multilevel measurement error autoregressive (MEAR) models. Results: No participants dropped out. Average response rates were 76% (CP) and 75% (control). The protocol was perceived as acceptable overall, though demanding by some participants. In the CP group, 61% of total variability in momentary fatigue was attributable to within-person fluctuations, and within-person reliability was 0.73 (SEM = 1.13). No evidence of reactivity to self-monitoring was found in fatigue ratings or qualitative interviews. FSS scores were positively associated with person-level average momentary fatigue, β = 0.51, p = 0.048. Conclusions: EMA is feasible in adults with CP and reveals substantial within-person fluctuations in fatigue. These findings provide initial proof-of-concept and inform methodological amendments for a future large-scale study of fatigue dynamics aiming to advance symptom management in this population.