Tracking daily fatigue fluctuations in multiple sclerosis: ecological momentary assessment provides unique insights

Abstract

Studies investigating the prevalence, cause, and consequence of multiple sclerosis (MS) fatigue typically use single measures that implicitly assume symptom-stability over time, neglecting information about if, when, and why severity fluctuates. We aimed to examine the extent of moment-to-moment and day-to-day variability in fatigue in relapsing-remitting MS and healthy individuals, and identify daily life determinants of fluctuations. Over 4 weekdays, 76 participants (38 relapsing-remitting MS; 38 controls) recruited from multiple sites provided real-time self-reports six times daily (n = 1661 observations analyzed) measuring fatigue severity, stressors, mood, and physical exertion, and daily self-reports of sleep quality. Fatigue fluctuations were evident in both groups. Fatigue was highest in relapsing-remitting MS, typically peaking in late-afternoon. In controls, fatigue started lower and increased steadily until bedtime. Real-time stressors and negative mood were associated with increased fatigue, and positive mood with decreased fatigue in both groups. Increased fatigue was related to physical exertion in relapsing-remitting MS, and poorer sleep quality in controls. In relapsing-remitting MS, fatigue fluctuates substantially over time. Many daily life determinants of fluctuations are similar in relapsing-remitting MS and healthy individuals (stressors, mood) but physical exertion seems more relevant in relapsing-remitting MS and sleep quality most relevant in healthy individuals.Electronic supplementary materialThe online version of this article (doi:10.1007/s10865-017-9840-4) contains supplementary material, which is available to authorized users.

Ecological Momentary Assessment of Pain, Fatigue, Depressive, and Cognitive Symptoms Reveals Significant Daily Variability in Multiple Sclerosis

“…Consistent with previous research 32,34,35 , these data show that in ambulatory people with MS, symptoms are not static, but are experienced dynamically. Fatigue emerged as the most variable symptom, with a high ratio of within- to between-person variability, and the greatest change from wake to bed time.…”

“…Examination of individual differences in symptom experience (versus group-level analyses) as well as how total symptom burden (versusindividual symptoms) in future research could better reflect the true experience of symptoms in MS; unfortunately, our relatively small sample precludes the type of data modeling that would be required to examine these question. Comparing daily symptom experience and impact in MS to other clinical conditions or to healthy individuals could provide additional insights as to how the symptoms experience is unique in MS, similar to a recent study showing that physical exertion is related to fatigue in MS whereas sleep quality is related to fatigue in healthy controls 35 .…”

“…Use of single item measures that have not been validated to assess momentary symptoms is a limitation of this study. Although there are examples of 0–10 numerical rating scale use in EMA studies of pain 80–82 and fatigue 33,35,82 , to our knowledge there are no standard, validated EMA measures of the symptoms examined in this study. Convergent validity of the EMA items, relative to more robust daily measures of each construct, was supported in this study.…”

“…In this study, we examined within-person variability and diurnal patterns in pain, fatigue, depressed mood, and cognitive function over 7 days. Based on previous findings 32,34,35 , we hypothesized that fatigue and depressed mood would demonstrate relatively higher levels of within-person variability compared to other symptoms and that all symptoms would exhibit a diurnal increase in severity throughout the day. We explored whether age, sex, MS subtype, MS duration, work status, and education level were related to different diurnal symptom patterns.…”

“…Studies that examined daily symptoms in MS have shown significant within-person variability in fatigue and depressed mood, with less variability for pain intensity 32,33 , significant individual differences in diurnal fluctuations in fatigue 34 , and significant daily fatigue fluctuations that are more related to physical exertion in those with compared to those without MS 35 . While these studies provide initial evidence as to daily symptom variability in MS, they are somewhat limited by small sample sizes 32,33,35 and a focus on fatigue 33,34 . Greater understanding of the variability of MS symptoms could provide insight into how symptoms are experienced in daily life, inform approaches to measuring symptoms, and optimize behavioral and pharmacological treatments for symptoms in MS.…”