Associations of daily walking activity with biomarkers related to cardiac distress in patients with chronic obstructive pulmonary disease.

BACKGROUND: The prevalence of cardiovascular mortality is high in Chronic Obstructive Pulmonary Disease (COPD) and the identification of clinical parameters to improve risk stratification is of great interest. OBJECTIVES: This study aims to assess the predictive strength of daily walking activity on expression of cardiac biomarkers in patients with COPD. METHODS: One hundred and five patients with COPD (66.1 ± 8.7 years of age) were prospectively analyzed. Daily walking activity was measured by means of accelerometry. Stepwise multivariate regression analyses were employed with either midregional proatrial natriuretic peptide (MRproANP) or plasma proadrenomedullin (MRproADM) as dependent variables, and age, age-adjusted Charlson score, Modified Medical Research Council Dyspnea Scale (MMRC), Saint Georges Respiratory Questionnaire total score and either total walk, steps per day or fast walk as covariates. RESULTS: Independent predictors of MRproANP included age (p = 0.015) and either total walk or steps per day (both p < 0.0001). Total walk or steps per day were the only independent predictors of MRproADM (p < 0.0001). There was a significant negative correlation between fast walk and MMRC (R = -0.70; p < 0.001) and fast walk was only independently predictive of MRproANP but not MRproADM once MMRC was excluded from the list of covariates (p = 0.023 and p = 0.057, respectively). CONCLUSIONS: Daily walking activity independently predicts levels of circulating MRproANP and MRproADM in stable COPD patients, two prognostic biomarkers of cardiac distress associated with long-term survival upon exacerbation of COPD. Employing activity monitors in the stable state might simplify risk stratification in daily living.