Jason, L A, King, C P, Frankenberry, E L et al. · Journal of clinical psychology · 1999 · DOI
This study looked at better ways to measure ME/CFS by tracking both symptoms and daily activity over time. Instead of just asking whether someone has symptoms, the researchers used rating scales and special devices to measure how severe symptoms are and how they change day-to-day. Two detailed case examples showed that this combined approach reveals important patterns that standard symptom checklists miss.
ME/CFS presents with highly variable symptoms that fluctuate unpredictably, making standard diagnostic checklists insufficient for clinical care. This study advocates for assessment methods that capture this complexity, which could lead to better diagnosis, more personalized treatment tracking, and improved clinical understanding of individual disease patterns. Improved assessment tools help clinicians and patients recognize triggers and patterns specific to their illness.
This study does not test whether the proposed assessment method is more effective for diagnosis than existing approaches, nor does it provide evidence about treatment outcomes. The case study design cannot establish prevalence of symptom patterns across CFS populations or prove causality between activity levels and symptom severity. The findings are illustrative rather than statistically generalizable.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Jason, L A, King, C P, Frankenberry, E L, Jordan, K M, Tryon, W W, Rademaker, F, et al. (1999). Chronic fatigue syndrome: assessing symptoms and activity level.. Journal of clinical psychology. https://doi.org/10.1002/(sici)1097-4679(199904)55:4<411::aid-jclp6>3.0.co;2-n
BibTeX
@article{mecfsatlas-jason-1999-chronic-fatigue,
author = {Jason, L A and King, C P and Frankenberry, E L and Jordan, K M and Tryon, W W and Rademaker, F and Huang, C F},
title = {Chronic fatigue syndrome: assessing symptoms and activity level.},
journal = {Journal of clinical psychology},
year = {1999},
doi = {10.1002/(sici)1097-4679(199904)55:4<411::aid-jclp6>3.0.co;2-n},
note = {PubMed: 10348404},
url = {https://www.mecfsatlas.com/evidence/jason-1999-chronic-fatigue},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/jason-1999-chronic-fatigue
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