| Abstract: |
Objective To test a model of nonimprovement in chronic fatigue syndrome (CFS) using self-report activity patterns (e.g., "push-crash"), uplifts and hassles, and a biological measure of cardiac autonomic function. Activity pattern impacts on symptoms and objective measures of autonomic and physical activity were also examined. Methods This prospective study in CFS collected all data remotely, including 6 months of weekly web diaries that recorded symptom ratings, activity patterns, and hassles and uplifts. In addition, 6 months of weekly heart monitoring and 3 months of daily waking actigraphy data were collected. Improvement or nonimprovement status was assessed using semistructured interviews at the 6-month follow-up. Results A total of 148 individuals (87.2% female) were enrolled, and 12.2% were lost to follow-up. Participants reporting nonimprovement (n = 92), as compared with improvement (n = 38), showed greater autonomic dysfunction (lower heart rate variability, group difference = 5.93 [SE = 2.73] milliseconds; p = .032) and lower mean intensity of behavioral uplifts (group difference = 0.14 [SE = 0.16]; p = .043), but no significant differences in any activity pattern, including push-crash, limiting activity, and healthy pacing. Conclusions This study provided evidence for linking patient-reported nonimprovement to a biological variable indexing autonomic dysfunction and a behavioral measure indicating a deficit in psychological uplifts. These findings suggest a possible marker of illness trajectory that could potentially advance the biomedical underpinnings of CFS. |
