Factors associated with health-related quality of life (HRQOL) in adults with chronic obstructive pulmonary disease (COPD)

Background: HRQOL is impaired in COPD patients. Regarding determining factors previous studies have yielded different results or did not use adequate designs, especially in Germany.

Purpose: The purpose of this study was to identify factors associated with HRQOL in patients with COPD.

Methods: Data for cross-sectional analyses were obtained from the baseline of a cohort study. The study population includes adult COPD patients (disease duration ≥3 months) without acute psychiatric/neurologic disease (exception: affective and anxiety disorders). HRQOL was assessed using the Short Form 12 (SF-12) Health Survey Questionnaire, which comprises a physical (PCS-12) and mental (MCS-12) component. Independent variables encompass socio-demographic, disease-specific, treatment-related and psychosocial factors. Information on variables was gathered by examining the patients' medical records and via self-administered questionnaires. We used multivariable linear regression analyses to investigate determinants of HRQOL.

Results: In total, 206 COPD patients (60.7% male; mean age: 65.3 years) took part in the study. In multivariable analysis, PCS-12 showed a significant negative association with insufficient disease control (measured by the COPD Assessment Test) and a higher number of medications taken in tablet form. A higher number of doctor visits during the last year and a higher FEV1 value in percent predicted was significantly related to PCS-12 in a positive manner. MCS-12 was significantly associated with elevated patient-reported symptoms of anxiety or depression (measured by the Hospital Anxiety and Depression Scale (HADS)) in a negative way. Like for PCS-12, worse disease control was significantly associated with lower MCS-12. Furthermore, being female was significantly associated with lower MCS-12.

Discussion: Disease control was the only factor associated with both the physical and the mental component of the SF-12. Health care utilization was related to better PCS-12 while lung function and number of medications, both of which reflect disease severity, were related to worse physical HRQOL. HADS and PCS-12 show some construct overlap. Severe and very severe stages of COPD may be overrepresented in our study population as compared to general COPD populations in Europe.

Conclusion: Focusing on disease control and screening for depression and anxiety might be promising approaches to improve HRQOL in patients with COPD.