Mueller, Tobias, Jerrentrup, Andreas, Bauer, Max Jakob et al. · Orphanet journal of rare diseases · 2016 · DOI
This study looked at 522 adults who visited a hospital center for help with diseases that hadn't been diagnosed yet. Most patients were women, and their main complaints were general weakness, joint pain, and stomach discomfort. The researchers found that many patients had been given diagnoses like chronic fatigue syndrome, fibromyalgia, or irritable bowel syndrome—conditions where symptoms are real but hard to explain with standard medical tests.
This study identifies that patients with unexplained medical conditions—including those with ME/CFS-like presentations—frequently seek care at specialized undiagnosed disease centers, highlighting a significant population in need of better diagnostic and therapeutic approaches. Understanding the demographics and symptom profiles of such patients helps optimize infrastructure and clinical pathways for interdisciplinary care. For ME/CFS researchers, the data underscore the need for clearer diagnostic criteria and better integration of medical and psychiatric expertise.
This study does not establish the prevalence of ME/CFS in the general population or among undiagnosed patients specifically, as ME/CFS was not the primary focus. The cross-sectional design cannot determine causation or establish whether somatoform diagnoses represent misdiagnosis of organic disease or genuine psychiatric comorbidity. The study also does not validate the diagnostic accuracy of prior diagnoses or track patient outcomes after assessment at the center.
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 →
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