Capturing Activity Pacing in People with Chronic Fatigue Syndrome Using Actigraphy

Abstract

Activity pacing is a common strategy in the management of chronic fatigue syndrome (CFS), often as a precursor to graded exercise therapy. Activity pacing involves planning daily and weekly activities, incorporating rest breaks and segmenting tasks into shorter time blocks, to avoid exacerbating the symptom of fatigue.

PURPOSE: The aim of this project was to examine the utility of actigraphy to elaborate on activity pacing behaviours, as measured with activity dairies, pedometers, self-report questionnaires and clinician ratings.

METHODS: Patients with CFS attending a tertiary specialist clinic completed specifically designed self-report questionnaires on activity participation and pacing, a 7-day activity diary and concurrently used a pedometer and actigraph. Pacing was quantified with the coefficient of variation of hourly step counts and the cumulative sum of vector magnitude counts. These indices were compared with formalised clinician ratings of each patient’s adherence to activity pacing strategies. A semi-structured interview was conducted regarding actigraph acceptance by patients.

RESULTS: The sample of 20 patients included 15 women (75%), with mean age of 32±14 years, mean duration of illness of 246±164 weeks and SF-36 physical function of 48.8±24.8. Of 22 patients to whom actigraphy was offered, 2 refused due to perceived inconvenience and 5 out of 20 experienced it as inconvenient. According to actigraph data, the mean percentage of time spent sedentary was 74.23%, at light intensity 17.34%, moderate intensity 4.26% and vigorous intensity 0.1%. Clinician ratings of activity pacing were generally unaffected by the availability of weekly activity traces from the actigraphs (r=0.67, p=0.25). Similarly the hourly fluctuation in actigraph recordings was not associated with clinician rating (r=0.270, p=0.250) and questionnaire scores (r=−0.106, p=0.656). Cumulative sum plots of weekly actigraphy data revealed substantial differences between patients in their activity patterns.

CONCLUSIONS: Actigraphy was reasonably well accepted, but was only modestly effective for providing an objective measure of pacing behaviour. More detailed analysis of the dispersion of bouts of activity and rest within and across days may enhance the utility of actigraphy for this purpose.