OBJECTIVES: We aimed to identify existing outcome measures for functional neurological disorder (FND), to inform the development of recommendations and to guide future research on FND outcomes. METHODS: A systematic review was conducted to identify existing FND-specific outcome measures and the most common measurement domains and measures in previous treatment studies. Searches of Embase, MEDLINE and PsycINFO were conducted between January 1965 and June 2019. The findings were discussed during two international meetings of the FND-Core Outcome Measures group. RESULTS: Five FND-specific measures were identified-three clinician-rated and two patient-rated-but their measurement properties have not been rigorously evaluated. No single measure was identified for use across the range of FND symptoms in adults. Across randomised controlled trials (k=40) and observational treatment studies (k=40), outcome measures most often assessed core FND symptom change. Other domains measured commonly were additional physical and psychological symptoms, life impact (ie, quality of life, disability and general functioning) and health economics/cost-utility (eg, healthcare resource use and quality-adjusted life years). CONCLUSIONS: There are few well-validated FND-specific outcome measures. Thus, at present, we recommend that existing outcome measures, known to be reliable, valid and responsive in FND or closely related populations, are used to capture key outcome domains. Increased consistency in outcome measurement will facilitate comparison of treatment effects across FND symptom types and treatment modalities. Future work needs to more rigorously validate outcome measures used in this population.

Academic Neurology Unit University of Sheffield Royal Hallamshire Hospital Sheffield UK

Department of Clinical Neurosciences School of Molecular and Clinical Medicine Western General Hospital University of Edinburgh Edinburgh UK

Department of Neurological Sciences Rush University Medical Center Chicago Illinois USA

Department of Neurology and Center of Clinical Neuroscience Charles University Prague Prague Czech Republic

Department of Neurology Feinberg School of Medicine Northwestern University Chicago Illinois USA

Department of Neurology Hopital Avicenne Assistance Publique Hôpitaux de Paris Paris Île de France France

Department of Neurology Medical University of Graz Graz Austria

Department of Neurology Radboud University Nijmegen Medical Centre Donders Institute for Brain Cognition and Behaviour Nijmegen Netherlands

Department of Neurology Stony Brook University Renaissance School of Medicine Stony Brook New York USA

Department of Neurology University Hospital Bern and University of Bern Bern Switzerland

Department of Neurology University Hospital Knappschaftskrankenhaus Bochum Ruhr University Bochum Bochum Germany

Department of Neurology University Medical Center Groningen University of Groningen Groningen Netherlands

Department of Neuroscience Biomedicine and Movement University of Verona Verona Italy

Department of Psychiatry Austin Health University of Melbourne Melbourne Victoria Australia

Department of Psychiatry Brigham and Women's Hospital Harvard Medical School Boston Massachusetts USA

Department of Psychiatry Georgetown University Washington District of Columbia USA

Departments of Neurology and Psychiatry and Behavioral Sciences Emory Centre for Ethics Emory University School of Medicine Atlanta Georgia USA

Departments of Neurology and Psychiatry Therapy Services Massachusetts General Hospital Harvard Medical School Boston MA United States

Departments of Psychiatry and Neurology Rhode Island Hospital Brown Medical School Providence RI USA

Discipline of Psychiatry and Child and Adolescent Health The Children's Hospital at Westmead Sydney Medical School Sydney New South Wales Australia

Donald Gordon Medical Centre University of the Witwatersrand Johannesburg South Africa

Epilepsy Research Center Shiraz Medical School Shiraz University of Medical Sciences Shiraz Iran Islamic Republic of

FND Hope International Salmon Idaho USA

Gardner Family Center for Parkinson's Disease and Movement Disorders Department of Neurology University of Cincinnati Cincinnati Ohio USA

Human Motor Control Section National Institute of Neurological Disorders and Stroke Bethesda Maryland USA

Institute of Mental Health Division of Psychiatry Faculty of Brain Sciences University College London London United Kingdom

Institute of Psychiatry Psychology and Neuroscience King's College London London UK

Jefferson Comprehensive Epilepsy Center Department of Neurology Thomas Jefferson University Philadelphia Pennsylvania USA

Mater Neurosciences Centre Brisbane Queensland Australia

Movement Disorders Clinic and the Edmond J Safra Program in Parkinson's Disease University Health Network Toronto Ontario Canada

Neuroscience Research Centre Institute of Molecular and Clinical Sciences St George's University London UK

Northeast Regional Epilepsy Group New York New York USA

Parkinson's Disease Center and Movement Disorders Clinic Department of Neurology Baylor College of Medicine Houston Texas USA

School of Health Sciences The University of Manchester Manchester UK

Therapy Services The National Hospital for Neurology and Neurosurgery London UK

University College London Institute of Neurology National Hospital for Neurology and Neurosurgery London UK

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