Depression and its relationship with poor exercise capacity, BODE index and muscle wasting in COPD.

BACKGROUND: The prevalence of depression in stable COPD patients varies markedly, possibly because of use of different scales. We aimed to assess depression using 2 different depression scales and to examine the association between depression and poor exercise performance, BODE index and muscle wasting in clinically stable COPD patients.
METHODS: 122 stable COPD patients were assessed with the Centre for Epidemiologic Studies Depression Scale (CES-D) and the Brief Assessment Schedule Depression Cards (BASDEC). We also assessed patients with spirometry, bioelectrical impedance analysis, 6-minute walk distance (6MWD), St George's Respiratory Questionnaire (SGRQ) and MRC dyspnoea and Borg scales.
RESULTS: The CES-D and BASDEC scales detected almost similar prevalence rates of depression (21% vs 17%) with a Kappa coefficient of 0.68, p<0.0001. The BASDEC scale detected more depression in women and was more closely associated with dyspnoea than the CES-D. COPD severity was associated with depression when using BODE scores but not when GOLD categories were used. Each of the CES-D and BASDEC depression scores were associated with 6MWD after adjusting for FEV1% predicted, gender, age and pack-years (p = <0.0001 and 0.001, respectively). Also, patients with a 6MWD<350 scored significantly higher on both depression scales. Wasted patients appeared to have higher depression scores, but the difference was statistically insignificant.
CONCLUSION: The administration of different depression scales may affect some of the characteristics of depressed patients rather than the prevalence rate of depression. Depression was associated with poor exercise performance and BODE index in COPD.