Independent determinants of disease-related quality of life in COPD - scope for non-pharmacological interventions?

Purpose: Quality of Life (QoL) scores in COPD have a weak relationship with physiological impairment. We investigated factors associated with poor QoL, focusing on psychological measures potentially amenable to intervention.
Patients and methods: We utilised a pre-existing Birmingham (UK) COPD cohort to assess factors associated with QoL impairment (CAT scores). Univariate and multivariate regression models were constructed from three categories of variables: demographic, lung function/COPD-related symptoms, and psychosocial/behavioural factors.
Results: Analyses were based on self-report questionnaire data from 735 participants. The multivariate model of variables independently associated with COPD Assessment Test (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 physiological impairment and patients’ experience of their disease. Interventions targeting psychological factors, illness perception and dysfunctional breathing should be assessed.