Objective Existing case definitions for chronic fatigue syndrome (CFS) all have disputed validity. The present study investigates differences between adolescent patients with CFS who satisfy the systemic exertion intolerance disease (SEID) diagnostic criteria (SEID-positive) and those who do not satisfy the criteria (SEID-negative).
Methods 120 adolescent patients with CFS with a mean age of 15.4 years (range 12–18 years) included in the NorCAPITAL project (ClinicalTrials ID: NCT01040429) were post-hoc subgrouped according to the SEID criteria based on a comprehensive questionnaire. The two subgroups were compared across baseline characteristics, as well as a wide range of cardiovascular, inflammatory, infectious, neuroendocrine and cognitive variables. Data from 30-week follow-up were used to investigate prognostic differences between SEID-positive and SEID-negative patients.
Results A total of 45 patients with CFS were SEID-positive, 69 were SEID-negative and 6 could not be classified. Despite the fact that clinically depressed patients were excluded in the NorCAPITAL project, the SEID-positive group had significantly higher score on symptoms suggesting a mood disorder (Mood and Feelings Questionnaire): 23.2 vs 13.4, difference 9.19 (95% CI 5.78 to 12.6). No other baseline characteristics showed any group differences. When accounting for multiple comparisons, there were no statistically significant differences between the groups regarding cardiovascular, inflammatory, infectious, neuroendocrine and cognitive variables. Steps per day and Chalder Fatigue Questionnaire at week 30 showed no differences between the groups.
Conclusion The findings question the discriminant and prognostic validity of the SEID diagnostic criteria in adolescent CFS, and suggest that the criteria tend to select patients with depressive symptoms.
- chronic fatigue syndrome
- adolescent health
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Contributors TTA and VBW conceptualised and designed the study, carried out the statistical analyses, drafted the initial manuscript, and reviewed and revised the manuscript. EF, DS and AW collected the data and contributed to drafting the manuscript. ES supervised statistical analyses, and critically reviewed and revised the manuscript.
Funding This study was funded by Health South-East Hospital Trust and the University of Oslo.
Competing interests None declared.
Patient consent Obtained.
Ethics approval The study was approved by the Norwegian National Committee for Ethics in Medical Research and the Norwegian Medicines Agency and adhered to the Declaration of Helsinki.
Provenance and peer review Not commissioned; externally peer reviewed.
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