Evans, Meredyth, Jason, Leonard A · Evaluation & the health professions · 2015 · DOI
This study looked at how accurately people with ME/CFS can remember and report their symptoms depending on how far back they think about (one week, one month, or six months). Researchers found that asking patients to recall symptoms from the past six months was most reliable for most symptoms, though joint pain was best recalled over one month. This matters because doctors need to know the best time frame to ask about when diagnosing ME/CFS.
Diagnostic accuracy for ME/CFS depends heavily on reliable symptom reporting, yet no standardized recall period had been empirically validated before this study. These findings provide clinicians and researchers with evidence-based guidance on optimal time frames for symptom assessment, potentially improving diagnostic consistency and reducing variability in clinical and research settings. This directly impacts how patients are diagnosed and how research studies collect comparable symptom data.
This study does not establish why certain symptoms are better recalled over longer periods, nor does it prove that longer recall times are universally better for all conditions. It also does not validate whether six-month recall is accurate in an absolute sense—only that it is more reliable than shorter periods. The study cannot explain the biological or cognitive mechanisms underlying these differences in recall reliability.
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
Evans, Meredyth & Jason, Leonard A (2015). Effects of Time Frame on the Recall Reliability of CFS Symptoms.. Evaluation & the health professions. https://doi.org/10.1177/0163278713497014
BibTeX
@article{mecfsatlas-evans-2015-effects-time,
author = {Evans, Meredyth and Jason, Leonard A},
title = {Effects of Time Frame on the Recall Reliability of CFS Symptoms.},
journal = {Evaluation & the health professions},
year = {2015},
doi = {10.1177/0163278713497014},
note = {PubMed: 24064428},
url = {https://www.mecfsatlas.com/evidence/evans-2015-effects-time},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/evans-2015-effects-time
Contribute
Private, reviewed by a human. Not a public comment thread.