Chronic obstructive pulmonary disease (COPD) is a highly incapacitating health problem, which not only affects physical functioning, but also leisure and professional activities as well as emotional and sexual relationships (Godoy and Godoy 2003
). COPD and associated symptoms, such as fatigue and dyspnoea, cause restrictions on patients’ exercise tolerance, consequently having a major impact on their ability to carry out daily activities, frequently resulting in reduced quality of life (Jones 2006
Because the airflow obstruction in COPD is largely irreversible, interventions for managing the disease are primarily aimed at improving patients’ health-related quality of life (Cully et al 2006
). As quality of life may be difficult to measure with a standardized questionnaire, illness-specific health status questionnaires, such as St. George’s Respiratory Questionnaire (SGRQ) (Jones et al 1992
) and Chronic Respiratory Questionnaire (CRQ) (Guyatt et al 1987
), provide means of quantifying the patients’ perceptions of the general effects of COPD on their daily life and wellbeing (Jones 2001
). Physiological parameters have been shown to correlate with health status (Ståhl et al 2005
), but in some studies the associations have been weak (Jones 2001
; McCathie et al 2002
), and even patients with mild disease have reported substantially impaired health status (Ferrer et al 1997
). The impact that COPD has on individuals living with the disease is likely to depend on multiple factors in addition to the medical burden, ranging from the patient’s life circumstances and expectations to coping skills and psychological well-being.
Previous research has shown that there is a high prevalence of anxiety and depression among COPD patients, and psychological distress has a profound impact on how persons with COPD experience and manage their disease (Hynninen et al 2005
). Psychological distress, as indicated by symptoms of anxiety and depression, has been reported to account for a significant amount of variance in health status in patients with moderate and severe COPD (Hajiro et al 2000
; Gudmundsson et al 2006
) as well as in hospitalized patients with acute exacerbations (Andenæs et al 2004
). Despite the frequency of anxiety and depression in COPD patients, only one previous study has focused on health status in patients with clinically significant levels of co-morbid depression and/or anxiety. Using a sample of veterans with COPD, Cully, Graham et al (2006)
found that mental health symptoms, and in particular symptoms of anxiety, were the most salient factors associated with health status outcomes, above and beyond COPD severity, medical co-morbidity, and demographic factors. However, participants in this study were primarily males, which limits the generalizability of the results.
In addition to being symptomatic of both anxiety and depression, disturbed sleep is also common in COPD. Sleep disturbance has been found to be the third most common symptom associated with COPD (Kinsman et al 1983
), and studies have revealed that low total sleep time, frequent arousals and awakenings, and reduced amounts of slow-wave and rapid eye movement sleep seem to characterize the sleep of COPD-patients (Ballard 2005
). Sleep disturbance in patients with severe COPD may be related to symptoms, such as nocturnal cough, wheezing, and dyspnoea, as a consequence of impaired pulmonary functions and gas exchange during sleep (Mohsenin 2005
). Psychological distress may, however, contribute to sleep difficulties in all stages of disease severity, and both anxiety and depression have been shown to have a negative effect on the sleep quality in COPD (Bellia et al 2003
; Kapella et al 2006
). Sleep impairment not only worsens quality of life but may also aggravate symptoms of the underlying medical disorder (Ballard 2005
). Thus, further investigation of the associations between sleep problems, psychological distress, and health status in COPD is needed.
The present study aimed at investigating factors associated with health status in a sample of COPD outpatients in all stages of disease severity, who additionally were suffering from symptoms of anxiety and/or depression. Because sleep problems may intensify the effects of a medical illness, difficulties with sleep were expected to be associated with health status impairment. Since psychological distress seems to play an important role in how patients experience their disease, it was also hypothesized that perceived health status would be more strongly related to psychological distress than to the severity of COPD. Furthermore, as women tend to have higher levels of psychological distress, females were expected to show more health status impairment regardless of their COPD severity.