Natural course and predicting self-reported improvement in patients with chronic fatigue syndrome with a relatively short illness duration

Objective: To describe the course of fatigue in chronic fatigue syndrome (CFS) patients with a relatively short duration of complaints and to test which psychosocial factors predict spontaneous improvement 1 year later.

Methods: Seventy-nine patients with a complaint duration of less than 2 years were tested at baseline and 78 of the same group at 1-year follow-up. During this time period, no systematic intervention took place. Self-reported improvement and fatigue severity were the main outcome measures.

Results: Forty-six percent (95% confidence intervals, 95CI = 35-58%) of the patients with a short illness duration reported to be improved. This was a significantly (chi(2) = 20.3, P < .001) higher percentage compared to the 20% (95CI = 15-26%) self-reported improvement in a previously published natural-course study among 246 CFS patients with a longer illness duration. Persistence of complaints after 1-year follow-up was associated with high baseline levels of experienced concentration problems, less strong psychosocial causal explanations for the complaints, and higher levels of the experienced lack of social support. Baseline fatigue severity predicted fatigue severity at follow-up.

Conclusion: The results showed that CFS patients with a relatively short duration of complaints had a more favourable outcome compared to patients with a long illness duration. The data also indicated that complete recovery only occurred in patients with a complaint duration of less than 15 months. This finding has important implications, since it suggests that after such a time period spontaneous recovery hardly occurs.