Background: Plasma endothelin and adrenomedullin are increased in patients with pulmonary arterial hypertension, hypoxia, and pulmonary infections, conditions that predict survival in patients with COPD. We investigated whether plasma pro-endothelin-1 (proET-1) and/or pro-adrenomedullin (proADM) on admission to the hospital for acute exacerbation predict survival in patients with COPD.
Methods: We examined 167 patients who had been admitted to the hospital for acute exacerbation, and we followed them up for 2 years. We measured plasma C-terminal (CT) proET-1 and mid-regional (MR) proADM on hospital admission, after 14 to 18 days, and after 6 months. In addition to plasma CT proET-1 and MR proADM, we assessed with Cox regression univariate and multivariate analyses the predictive value of clinical, functional, and laboratory parameters on 2-year survival. We analyzed the time to death by Kaplan-Meier curves.
Results: Compared to recovery and stable state, CT-proET-1 and MR-proADM were significantly increased on hospital admission (p < 0.001 and p = 0.002, respectively). MR-proADM, but not CT-proET-1, was associated with increased in-hospital mortality (p = 0.049) and independently predicted 2-year survival (p = 0.017). ProADM plasma levels > 0.84 nmol/L on hospital admission increased the mortality risk within 2 years from 13 to 32% (p = 0.004). By contrast, age (p = 0.779), Charlson comorbidity score (p = 0.971), body mass index (p = 0.802), FEV(1) percent predicted (p = 0.741), PAo(2) (p = 0.744), PAco(2) (p = 0.284), leukocyte counts (p = 0.333), C-reactive protein (p = 0.772), procalcitonin (p = 0.069), pulmonary arterial hypertension (p = 0.971), and CT-proET-1 (p = 0.223) were not independently associated with 2-year survival.
Conclusions: This study shows that plasma proADM but not plasma proET-1 on admission to the hospital for acute exacerbation independently predicts survival, thus suggesting that this biomarker could be used to predict prognosis in patients with COPD.