Background: Recently, the use of systemic biomarkers to monitor and assess the clinical evolution of respiratory disease has gained interest. We investigated whether midregional proatrial natriuretic peptide (MR-proANP) predicts survival in patients with COPD when they are admitted to the hospital for exacerbation.
Methods: One hundred sixty-seven patients (mean age 70 years old, 75 men) admitted to the hospital for exacerbation were followed up for 2 years. MR-proANP was measured on admission, after 14 days, and at 6 months. The predictive value of clinical, functional, and laboratory parameters on admission were assessed by Cox regression analyses. The time to death was analyzed by Kaplan-Meier survival curves.
Results: MR-proANP level was significantly higher on admission for exacerbation, compared with recovery and stable state (P = .004 for the comparison among all time points). MR-proANP correlated with the Charlson condition and age-related score (P < .0001), left ventricular ejection fraction (P < .0001), C-reactive protein (P = .037), and FEV(1)% predicted (P = .004). MR-proANP levels were similar in patients requiring ICU treatment and in those treated in the medical ward (P = .086). Thirty-seven patients (22%) died within 2 years. MR-proANP levels were higher in nonsurvivors compared with survivors (median [interquartile range] 185 pmol/L [110-286] vs 92 pmol/L [56-158], P < .001). Mortality was higher across MR-proANP quartiles (log rank P < .0001). Charlson condition and age-related score (P = .001), Paco(2) (P < .0001), and MR-proANP (P = .001) predicted mortality in the univariate Cox-regression model. Both MR-proANP and Paco(2) were independent predictors of mortality in the multivariate Cox regression model.
Conclusions: MR-proANP at exacerbation is associated with 2-year long-term survival in patients with exacerbation of COPD.