To evaluate the daily experience of patients with rheumatoid arthritis (RA) in an ecologically valid manner; Ecological Momentary Assessment (EMA) was employed. Diurnal cycles and within-day variation of self-reported pain and fatigue were examined as were relationships between pain, fatigue, daily stressful events, and sleep.
Thirty-five patients with RA were alerted with an electronic beep 7 times per day for 7 consecutive days. Assessments were recorded at each beep. Upon awakening each day, sleep information was reported.
There were large individual differences in variation of pain and fatigue. Stressors were associated with increased pain but not fatigue. Subjects with poor sleep had higher levels of pain and fatigue. Diurnal cycles of pain and fatigue were found, yet were observed for only some patients (37% and 34%, respectively).
The use of EMA deepens our understanding of the pain and fatigue experienced by RA patients. This method may help identify subgroups of patients who are highly "psychoreactive" to environmental stimuli and/or who have diurnal patterns to their symptoms. It may also be used to improve existing instruments.