ACHTSAM study protocol: outreach diagnostics and assessment of tolerability in severe ME/CFS—a pilot study

INTRODUCTION: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a severe, multisystem condition that often emerges after viral infections and affects physical and cognitive function. Severely affected patients are underrepresented in research due to immobility and exertional intolerance. METHODS: This is a prospective, non-interventional observational study investigating the feasibility and tolerability of home-based diagnostics in patients with severe and very severe ME/CFS. Phase 1 includes remote identification using validated questionnaires. Phase 2 involves home visits for physiological, cognitive and biological assessments. The primary outcome is feasibility; secondary outcomes include tolerability and methodological barriers. ETHICS/DISSEMINATION: The study protocol was approved by the Ethics Committee of the University of Freiburg (No. 25-1031-S1). Written informed consent is obtained from all participants. Results will be disseminated via peer-reviewed publications and patient support groups. TRIAL REGISTRATION NUMBER: DRKS00035231; FRKS005506.