Independent determinants of disease-related quality of life in COPD – scope for nonpharmacologic interventions?

Abstract

Purpose

Quality-of-life (QoL) scores in chronic obstructive pulmonary disease (COPD) have a weak relationship with physiologic impairment. We investigated factors associated with poor QoL, focusing on psychological measures potentially amenable to intervention.

Patients and methods

We utilized a pre-existing Birmingham (UK) COPD cohort to assess factors associated with QoL impairment (COPD Assessment Test [CAT] scores). Univariate and multivariate regression models were constructed from three categories of variables: demographic, lung function/COPD-related symptoms, and psychosocial/behavioral factors.

Results

Analyses were based on self-report questionnaire data from 735 participants. The multivariate model of variables independently associated with CAT included depression, dysfunctional breathing symptoms (Nijmegen score), and illness perception, in addition to COPD symptoms (wheeze, cough), exercise capacity, breathlessness, exacerbations, and deprivation; this model explained 72% of CAT score variation. In a dominance analysis assessing the relative contribution of variables, similar contributions were made by breathlessness (20.2%), illness perception (19.8%), dysfunctional breathing symptoms (17.5%), and depression (12.5%) with other variables contributing <5%.

Conclusion

Psychological factors significantly contribute to disease-specific QoL impairment in COPD, and potentially explain the mismatch between objective physiologic impairment and patients’ experience of their disease. Interventions targeting psychological factors, illness perception, and dysfunctional breathing should be assessed.

Keywords:

• chronic obstructive pulmonary disease
• quality of life
• health status
• survey
• psychological
• dysfunctional breathing
• breathlessness
• illness perception
• depression

Acknowledgments

This paper presents independent research funded by the National Institute for Health Research School for Primary Care Research (NIHR SPCR, project ref: 239). The BLISS cohort is funded by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research (grant reference number RP-PG-0109-10061). The views expressed are those of the author(s) and not necessarily those of the NIHR, the NHS, or the Department of Health. The Birmingham COPD Cohort study is part of the Birmingham Lung Improvement Studies: BLISS.

Author contributions

The original conception of the study came from SBB and MT, with input from all authors. Overall study management was by SBB. The BLISS cohort is conceived and managed by PA, REJ, and APD, who managed data acquisition and management. TK provided expertise in psychological morbidity and BS was the study statistician. All authors contributed toward data analysis, drafting and revising the paper and agree to be accountable for all aspects of the work.

Disclosure

MT declares personal fees from GSK, Novartis, BI, and Aerocrine, outside the submitted work. The authors report no other conflicts of interest in this work.