title: Can the Cancer-related Fatigue Case-definition Criteria Be Applied to Chronic Medical Illness? A Comparison between Breast Cancer and Systemic Sclerosis.
abstract: OBJECTIVE
  Fatigue is a crucial determinant of quality of life across rheumatic diseases, but the lack of agreed-upon standards for identifying clinically significant fatigue hinders research and clinical management. Case definition criteria for cancer-related fatigue were proposed for inclusion in the International Classification of Diseases. The objective was to evaluate whether the cancer-related fatigue case definition performed equivalently in women with breast cancer and systemic sclerosis (SSc) and could be used to identify patients with chronic illness-related fatigue.
  
  
  METHODS
  The cancer-related fatigue interview (case definition criteria met if ≥ 5 of 9 fatigue-related symptoms present with functional impairment) was completed by 291 women with SSc and 278 women successfully treated for breast cancer. Differential item functioning was assessed with the multiple indicator multiple cause model.
  
  
  RESULTS
  Items 3 (concentration) and 10 (short-term memory) were endorsed significantly less often by women with SSc compared with cancer, controlling for responses on other items. Omitting these 2 items from the case definition and requiring 4 out of the 7 remaining symptoms resulted in a similar overall prevalence of cancer-related fatigue in the cancer sample compared with the original criteria (37.4% vs 37.8%, respectively), with 97.5% of patients diagnosed identically with both definitions. Prevalence of chronic illness-related fatigue was 36.1% in SSc using 4 of 7 symptoms.
  
  
  CONCLUSIONS
  The cancer-related fatigue criteria can be used equivalently to identify patients with chronic illness-related fatigue when 2 cognitive fatigue symptoms are omitted. Harmonized definitions and measurement of clinically significant fatigue will advance research and clinical management of fatigue in rheumatic diseases and other conditions.
authors.affiliation: From the Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University; Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada; Division of Population Health Sciences and Education, St. Georges University of London; Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; Norfolk and Norwich University Hospitals National Health Service (NHS) Foundation Trust, Norwich, UK.L. Kwakkenbos, PhD, Department of Psychiatry, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital; O. Minton, PhD, Division of Population Health Sciences and Education, St. Georges University of London; P.C. Stone, MD, Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; S. Alexander, PhD, Norfolk and Norwich University Hospitals NHS Foundation Trust; M. Baron, MD; M. Hudson, MD, Lady Davis Institute for Medical Research, and Department of Medicine, McGill University; B.D. Thombs, PhD, Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital. kwakkenbosL@gmail.com.
authors.forename: Linda
authors.initials: L
authors.lastname: Kwakkenbos
authors.affiliation: From the Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University; Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada; Division of Population Health Sciences and Education, St. Georges University of London; Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; Norfolk and Norwich University Hospitals National Health Service (NHS) Foundation Trust, Norwich, UK.L. Kwakkenbos, PhD, Department of Psychiatry, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital; O. Minton, PhD, Division of Population Health Sciences and Education, St. Georges University of London; P.C. Stone, MD, Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; S. Alexander, PhD, Norfolk and Norwich University Hospitals NHS Foundation Trust; M. Baron, MD; M. Hudson, MD, Lady Davis Institute for Medical Research, and Department of Medicine, McGill University; B.D. Thombs, PhD, Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital.
authors.forename: Ollie
authors.initials: O
authors.lastname: Minton
authors.affiliation: From the Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University; Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada; Division of Population Health Sciences and Education, St. Georges University of London; Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; Norfolk and Norwich University Hospitals National Health Service (NHS) Foundation Trust, Norwich, UK.L. Kwakkenbos, PhD, Department of Psychiatry, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital; O. Minton, PhD, Division of Population Health Sciences and Education, St. Georges University of London; P.C. Stone, MD, Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; S. Alexander, PhD, Norfolk and Norwich University Hospitals NHS Foundation Trust; M. Baron, MD; M. Hudson, MD, Lady Davis Institute for Medical Research, and Department of Medicine, McGill University; B.D. Thombs, PhD, Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital.
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Stone
authors.affiliation: From the Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University; Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada; Division of Population Health Sciences and Education, St. Georges University of London; Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; Norfolk and Norwich University Hospitals National Health Service (NHS) Foundation Trust, Norwich, UK.L. Kwakkenbos, PhD, Department of Psychiatry, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital; O. Minton, PhD, Division of Population Health Sciences and Education, St. Georges University of London; P.C. Stone, MD, Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; S. Alexander, PhD, Norfolk and Norwich University Hospitals NHS Foundation Trust; M. Baron, MD; M. Hudson, MD, Lady Davis Institute for Medical Research, and Department of Medicine, McGill University; B.D. Thombs, PhD, Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital.
authors.forename: Susanna
authors.initials: S
authors.lastname: Alexander
authors.affiliation: From the Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University; Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada; Division of Population Health Sciences and Education, St. Georges University of London; Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; Norfolk and Norwich University Hospitals National Health Service (NHS) Foundation Trust, Norwich, UK.L. Kwakkenbos, PhD, Department of Psychiatry, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital; O. Minton, PhD, Division of Population Health Sciences and Education, St. Georges University of London; P.C. Stone, MD, Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; S. Alexander, PhD, Norfolk and Norwich University Hospitals NHS Foundation Trust; M. Baron, MD; M. Hudson, MD, Lady Davis Institute for Medical Research, and Department of Medicine, McGill University; B.D. Thombs, PhD, Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital.
authors.forename: Murray
authors.initials: M
authors.lastname: Baron
authors.affiliation: From the Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University; Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada; Division of Population Health Sciences and Education, St. Georges University of London; Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; Norfolk and Norwich University Hospitals National Health Service (NHS) Foundation Trust, Norwich, UK.L. Kwakkenbos, PhD, Department of Psychiatry, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital; O. Minton, PhD, Division of Population Health Sciences and Education, St. Georges University of London; P.C. Stone, MD, Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; S. Alexander, PhD, Norfolk and Norwich University Hospitals NHS Foundation Trust; M. Baron, MD; M. Hudson, MD, Lady Davis Institute for Medical Research, and Department of Medicine, McGill University; B.D. Thombs, PhD, Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital.
authors.forename: Marie
authors.initials: M
authors.lastname: Hudson
authors.affiliation: From the Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University; Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, Québec, Canada; Division of Population Health Sciences and Education, St. Georges University of London; Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; Norfolk and Norwich University Hospitals National Health Service (NHS) Foundation Trust, Norwich, UK.L. Kwakkenbos, PhD, Department of Psychiatry, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital; O. Minton, PhD, Division of Population Health Sciences and Education, St. Georges University of London; P.C. Stone, MD, Marie Curie Palliative Care Research Department, Division of Psychiatry, University College London; S. Alexander, PhD, Norfolk and Norwich University Hospitals NHS Foundation Trust; M. Baron, MD; M. Hudson, MD, Lady Davis Institute for Medical Research, and Department of Medicine, McGill University; B.D. Thombs, PhD, Department of Psychiatry, Department of Medicine, Department of Epidemiology, Biostatistics and Occupational Health, Department of Educational and Counselling Psychology, Department of Psychology, and School of Nursing, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital.
authors.forename: Brett D
authors.initials: BD
authors.lastname: Thombs
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000150:complications*; D002908:Chronic Disease; D005221:Fatigue / Q000175:diagnosis* / Q000209:etiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011788:Quality of Life; D012595:Scleroderma, Systemic / Q000150:complications*; D012720:Severity of Illness Index
keywords: FATIGUE; NEOPLASMS; PATIENT OUTCOME ASSESSMENT; PSYCHOMETRICS; SYSTEMIC SCLERODERMA