Complications in operationalizing lifelong fatigue as an exclusionary criterion.
Sunnquist, Madison, Jason, Leonard A, Brown, Abigail et al. · Journal of prevention & intervention in the community · 2015 · DOI
Quick Summary
This study looked at whether people who have felt tired their whole lives should be excluded from ME/CFS diagnoses. Researchers asked patients detailed questions about lifelong fatigue and found it was very difficult to determine who truly had it. Importantly, people with and without lifelong fatigue had similar ME/CFS symptoms, suggesting this exclusion rule may not be helpful.
Why It Matters
ME/CFS case definitions are critical for ensuring patients receive appropriate diagnosis and care. If the lifelong fatigue exclusion criterion is unclear and doesn't actually distinguish between patients, it may be incorrectly excluding people who have ME/CFS, leading to missed diagnoses and delayed treatment. This study provides evidence supporting revision of diagnostic criteria to be more inclusive and scientifically sound.
Observed Findings
Using rigorous classification standards, only a small number of study participants were identified as having lifelong fatigue.
Participants with lifelong fatigue and those without lifelong fatigue showed few significant differences in ME/CFS symptoms.
Participants with and without lifelong fatigue showed few significant differences in functional impairment areas.
Substantial complexity and ambiguity were encountered in the process of determining lifelong fatigue status from questionnaire responses.
The DePaul Symptom Questionnaire was used as the measurement tool for assessing fatigue history.
Inferred Conclusions
Lifelong fatigue is difficult to operationalize reliably and measure with validity in clinical or research settings.
Lifelong fatigue does not meaningfully differentiate between people with and without ME/CFS symptoms or functional impairment.
Lifelong fatigue should be removed as an exclusionary criterion from ME/CFS case definitions due to lack of clinical utility.
Current ME/CFS case definitions may benefit from revision to improve diagnostic accuracy and inclusivity.
Remaining Questions
How do different measurement approaches and questionnaires compare in their ability to reliably assess lifelong fatigue?
What This Study Does Not Prove
This study does not prove that lifelong fatigue does not exist as a clinical phenomenon, only that it is difficult to measure reliably and may not be a valid exclusionary criterion. The study's findings about symptom similarity do not establish causation or definitively explain why lifelong fatigue should be removed beyond operational difficulties. This is a methods paper, not a large-scale validation study across diverse populations.