ME/CFS (ICD-10 G93.3) is a multisystem chronic disease that can lead to severe
disability. Pre-pandemic prevalence was estimated at approximately 0.3% worldwide, and
increasing prevalence is observed due to ME/CFS in the context of long-term sequelae of
coronavirus diseases 2019 (COVID-19). In Germany, the number of affected people in
Germany was estimated as approximately 350.000-400.000 in 2018/2019 and almost 500.000 in
2021. ME/CFS can manifest at any age, with peak prevalence in adolescents and young
adults. Common triggers include COVID, influenza, and Epstein-Barr virus-associated
infectious mononucleosis (EBV-IM). Non-infectious triggers are known as well.
Autoimmunity and dysfunction of the autonomic nervous system (ANS) were suggested as
possible pathomechanisms. Core symptoms include fatigue, post-exertional malaise (PEM),
and unrefreshing sleep. Additional symptoms comprise cognitive deficits ("brain fog"),
orthostatic intolerance, neuroendocrine, and immunological symptoms. ME/CFS is diagnosed
according to clinical criteria (mostly criteria by the Institute of Medicine (IOM) or
Canadian Consensus Criteria) and by appropriate differential diagnostics to exclude other
disorders with similar symptoms. So far, no biomarker or specific therapy is available.
Therapeutic approaches are holistic and aim at the palliation of symptoms as well as
psychosocial support. Self-management with pacing is recommended. Knowledge of ME/CFS
among healthcare providers is still scarce, and many patients do not receive adequate
care.

With this web-based, German-wide registry, the investigators aim at deep phenotyping of
the disease, identification of subtypes and risk factors, describing trajectories of the
disease and patient journeys, and providing clinical data for future clinical trials.
Patients are also invited to contribute biosamples for future translational research.