title: Minimal clinically important difference (MCID) for the functional assessment of cancer therapy: cognitive function (FACT-Cog) in breast cancer patients.
abstract: OBJECTIVE
  This is the first reported study to determine the minimal clinically important difference (MCID) of Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog), a validated subjective neuropsychological instrument designed to evaluate cancer patients' perceived cognitive deterioration.
  
  
  METHODS
  Breast cancer patients (n = 220) completed FACT-Cog and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC-QLQ-C30) at baseline and at least 3 months later. Anchor-based approach used the validated EORTC-QLQ-C30-Cognitive Functioning scale (EORTC-CF) as the anchor for patients who showed minimal deterioration and a receiver operating characteristic (ROC) curve to identify the optimal MCID cutoff for deterioration. Distribution-based approach used one-third standard deviation (SD), half SD, and one standard error of measurement (SEM) of the total FACT-Cog score (148 points).
  
  
  RESULTS
  There was a moderate correlation between changes in FACT-Cog and EORTC-CF scores (r = 0.43; P < 0.001). The EORTC-CF-anchored MCID was 9.6 points (95% confidence interval: 4.4, 14.8). The MCID from the ROC method was 7.5 points (area under the curve: 0.75; sensitivity: 75.6%; specificity: 68.8%). For the distribution-based approach, the MCIDs corresponding to one-third SD, half SD, and one SEM were 6.9, 10.3, and 10.6 points, respectively. Combining the approaches, the MCID identified for FACT-Cog ranged from 6.9 to 10.6 points (4.7-7.2% of the total score).
  
  
  CONCLUSIONS
  The estimates of 6.9-10.6 points as MCID can facilitate the interpretation of patient-reported cognitive deterioration and sample size estimates in future studies.
authors.affiliation: Department of Pharmacy, National University of Singapore, 18 Science Drive 4, Singapore 117543; Department of Pharmacy, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610.
authors.forename: Yin Ting
authors.initials: YT
authors.lastname: Cheung
authors.affiliation: Department of Pharmacy, National University of Singapore, 18 Science Drive 4, Singapore 117543.
authors.forename: Yu Lee
authors.initials: YL
authors.lastname: Foo
authors.affiliation: Department of Pharmacy, National University of Singapore, 18 Science Drive 4, Singapore 117543.
authors.forename: Maung
authors.initials: M
authors.lastname: Shwe
authors.affiliation: Department of Psychosocial Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610.
authors.forename: Yee Pin
authors.initials: YP
authors.lastname: Tan
authors.affiliation: Department of Psychosocial Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610.
authors.forename: Gilbert
authors.initials: G
authors.lastname: Fan
authors.affiliation: Department of Surgical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610.
authors.forename: Wei Sean
authors.initials: WS
authors.lastname: Yong
authors.affiliation: Department of Surgical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610.
authors.forename: Preetha
authors.initials: P
authors.lastname: Madhukumar
authors.affiliation: Department of Medical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610.
authors.forename: Wei Seong
authors.initials: WS
authors.lastname: Ooi
authors.affiliation: Department of Medical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610.
authors.forename: Wen Yee
authors.initials: WY
authors.lastname: Chay
authors.affiliation: Department of Medical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610; Department of Clinical Sciences, Duke-NUS Graduate Medical School Singapore, 8 College Road Singapore 169857.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Dent
authors.affiliation: Department of Medical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610.
authors.forename: Soo Fan
authors.initials: SF
authors.lastname: Ang
authors.affiliation: Department of Medical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610.
authors.forename: Soo Kien
authors.initials: SK
authors.lastname: Lo
authors.affiliation: Department of Medical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610.
authors.forename: Yoon Sim
authors.initials: YS
authors.lastname: Yap
authors.affiliation: Department of Medical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610; Department of Clinical Sciences, Duke-NUS Graduate Medical School Singapore, 8 College Road Singapore 169857.
authors.forename: Raymond
authors.initials: R
authors.lastname: Ng
authors.affiliation: Department of Pharmacy, National University of Singapore, 18 Science Drive 4, Singapore 117543; Department of Pharmacy, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610. Electronic address: phaac@nus.edu.sg.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Chan
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000523:psychology* / Q000628:therapy*; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D011446:Prospective Studies; D011788:Quality of Life; D012372:ROC Curve; D057566:Self Report / Q000592:standards; D011795:Surveys and Questionnaires
keywords: Breast cancer; Chemotherapy; Cognitive function; FACT-Cog; Minimal clinically important difference; Quality of life