Memory for fatigue in chronic fatigue syndrome: The relation between weekly recall and momentary ratings

Background: Understanding how patients with chronic fatigue syndrome (CFS) recall their fatigue is important because fatigue is a core clinical dimension of this poorly understood illness. Purpose: This study assessed the associations between momentary fatigue ratings and weekly recall of fatigue in 71 participants with CFS. Method: During the three-week data collection period, fatigue intensity was recorded six times a day in electronic diaries. At the end of each week, participants were asked to recall their fatigue intensity for that week. Statistical analyses were done with t-tests and Pearson's and intraclass correlations. Results: Average weekly recall of fatigue intensity was significantly higher than average momentary ratings. Furthermore, moderate to high Pearson's correlations and intraclass correlations (consistency and absolute agreement) between recall and momentary fatigue ratings were found. Conclusion: Individuals with CFS recalled consistently higher levels of fatigue in comparison to real-time momentary ratings, yet the level of agreement between the two measures was moderate to high. These findings may have implications for the conduct of office examinations for CFS.