Background:The aim of this study was to determine the influence of selected
physiological, psychological and situational factors on experience of
fatigue, and functional limitations due to fatigue in patients with stable
chronic obstructive pulmonary disease (COPD).Methods:In total 101 patients with COPD and 34 control patients were assessed for
experience of fatigue, functional limitation due to fatigue (Fatigue Impact
Scale), physiological [lung function, 6-minute walk distance (6MWD), body
mass index (BMI), dyspnoea, interleukin (IL)-6, IL-8, high sensitivity
C-reactive protein (hs-CRP), surfactant protein D], psychological (anxiety,
depression, insomnia), situational variables (age, sex, smoking, living
alone, education), and quality of life.Results:Fatigue was more common in patients with COPD than in control patients (72%
versus 56%, p < 0.001). Patients
with COPD and fatigue had lower lung function, shorter 6MWD, more dyspnoea,
anxiety and depressive symptoms, and worse health status compared with
patients without fatigue (all p < 0.01). No differences
were found for markers of systemic inflammation. In logistic regression,
experience of fatigue was associated with depression [odds ratio (OR) 1.69,
95% confidence interval (CI) 1.28–2.25) and insomnia (OR 1.75, 95% CI
1.19–2.54). In linear regression models, depression, surfactant protein D
and dyspnoea explained 35% (R2) of the variation
in physical impact of fatigue. Current smoking and depression explained 33%
(R2) of the cognitive impact of fatigue.
Depression and surfactant protein D explained 48%
(R2) of the psychosocial impact of
fatigue.Conclusions:Experiences of fatigue and functional limitation due to fatigue seem to be
related mainly to psychological but also to physiological influencing
factors, with depressive symptoms, insomnia problems and dyspnoea as the
most prominent factors. Systemic inflammation was not associated with
perception of fatigue but surfactant protein D was connected to some
dimensions of the impact of fatigue