Examining fatigue in COPD: development, validity and reliability of a modified version of FACIT-F scale.
BACKGROUND
Fatigue is a disruptive symptom that inhibits normal functional performance of COPD patients in daily activities. The availability of a short, simple, reliable and valid scale would improve assessment of the characteristics and influence of fatigue in COPD.


METHODS
At baseline, 2107 COPD patients from the ECLIPSE cohort completed the Functional Assessment of Chronic Illness Therapy Fatigue (FACIT-F) scale. We used well-structured classic method, the principal components analysis (PCA) and Rasch analysis for structurally examining the 13-item FACIT-F.


RESULTS
Four items were less able to capture fatigue characteristics in COPD and were deleted. PCA was applied to the remaining 9 items of the modified FACIT-F and resulted in three interpretable dimensions: i) general (5 items); ii) functional ability (2 items); and iii) psychosocial fatigue (2 items). The modified FACIT-F had high internal consistency (Cronbach's α = 0.91) and it did not fit a uni-dimensional Rasch model, confirming the prior output from the PCA. The correlations between total score and each dimension were ≥ 0.64 and within dimensions ≥0.43 (p < 0.001 for all).The original and modified FACIT-F had significant convergent validity; its scores were associated with SGRQ total score (0.69 and 0.7) and mMRC dyspnoea scores (0.48 and 0.47), (p = <0.001 for all). The scale had meaningful discriminating ability in identifying patients with poor exercise performance and more depressive symptoms.


CONCLUSIONS
The original and modified FACIT-F are valid and reliable scales in COPD. The modified version is shorter and measures not only total fatigue but also its sub-components in COPD.
University of Manchester, Medicines Evaluation Unit, NIHR Translational Research Facility, Manchester Academic Health Sciences Centre, University Hospital of South Manchester Foundation Trust, Wythenshawe, Manchester, UK. alshair02@yahoo.com
Khaled
K
Al-shair
Hana
H
Muellerova
Janelle
J
Yorke
Stephen I
SI
Rennard
Emiel F M
EF
Wouters
Nicola A
NA
Hanania
Amir
A
Sharafkhaneh
Jørgen
J
Vestbo
D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D001993:Bronchodilator Agents; D003627:Data Interpretation, Statistical; D005221:Fatigue / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D025341:Principal Component Analysis; D011594:Psychometrics / Q000295:instrumentation*; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000523:psychology / Q000628:therapy; D011788:Quality of Life / Q000523:psychology; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D012907:Smoking / Q000453:epidemiology / Q000523:psychology; D011795:Surveys and Questionnaires / Q000592:standards*; D014797:Vital Capacity / Q000502:physiology
D001993:Bronchodilator Agents