Associated factors of fatigue in patients with COPD: results from the FAntasTIGUE study.

Background: Fatigue is present in about half of the patients with COPD. The associated factors of fatigue in COPD remain unclear and have not been studied in an integrated and holistic analysis. The aim of this study is to identify associated factors of fatigue in COPD. Methods: In this cross-sectional study, clinically stable patients with COPD from primary and secondary care were assessed for fatigue (Checklist Individual Strength Subjective Fatigue (CIS-Fatigue)), other symptoms, medication, and personal, COPD-related, physical, psychological and systemic factors. Multivariable stepwise regression analyses were performed for each domain, followed by a multivariable (enter) model with all identified factors. Results: In total, 247 patients with COPD (67±8 years, 60% male, forced expiratory volume in 1 s 57±21% predicted, 27% Global Initiative for Chronic Obstructive Lung Disease (GOLD) E) were included in the study of which 51% reported severe fatigue (CIS-Fatigue ≥36 points). Distinct models for each group of factors identified the following factors associated with a higher level of fatigue: living alone, antidepressant use, anxiolytic use, systemic antihistamines use, higher Charlson comorbidity score, lower diffusion capacity, higher number of moderate exacerbations in the last year, higher dyspnoea, reduced sleep quality, higher pain, lower functional exercise capacity, higher fatigue-related catastrophising, more depressive symptoms, lower calcium and higher leukocyte count. The final model explained 46.6% of variance in fatigue with dyspnoea, sleep quality, fatigue-catastrophising and pain as significant associated factors (F(17, 184)=11.312, p<0.001). Conclusion: Pain, sleep quality, dyspnoea and fatigue-catastrophising were identified as associated factors of fatigue. These factors should not be overlooked when treating fatigue in patients with COPD.