What Is the Value of Midregional Proatrial Natriuretic Peptide in COPD Research or Clinical Practice?: Response

Abstract

We thank Drs Alrajab and Uysal for their interest in our recent article in CHEST on midregional proatrial natriuretic peptide (MR-ProANP) in patients hospitalized for acute exacerbation of COPD1Bernasconi M Tamm M Bingisser R et al.Midregional proatrial natriuretic peptide predicts survival in exacerbations of COPD.Chest. 2011; 140: 91-99Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar and their concerns regarding the value of MR-ProANP in research or clinical practice. Although we refrained from performing right-sided heart catheterizations in this high-risk population, the presence of pulmonary hypertension was objectively assessed by echocardiography. It is well known that pulmonary pressures may be acutely increased during acute exacerbation of COPD, supporting the assessment of pulmonary pressures at the stable state of the disease. Cardiopathy was present in 45.5% of the patients. The high prevalence of cardiac disease and cardiac-related death in patients with severe acute exacerbation of COPD is consistent with the data of the Towards a Revolution in COPD Health (TORCH) study,2McGarvey LP John M Anderson JA Zvarich M Wise RA TORCH Clinical Endpoint Committee Ascertainment of cause-specific mortality in COPD: operations of the TORCH Clinical Endpoint Committee.Thorax. 2007; 62: 411-415Crossref PubMed Scopus (410) Google Scholar underlying the importance of cardiovascular disease in patients with COPD and highlighting the interest in markers of heart disease as potential prognostic biomarkers in this population. A major finding of the study is that both Paco2 and MR-ProANP were better prognostic parameters than historic markers of disease severity, including the parameter currently used to target therapy in COPD (ie, FEV1). The complexity and the heterogeneity of COPD strongly suggest the need for a composite score (such as the BMI, airflow obstruction, dyspnea, and exercise capacity [BODE] score) or a disease-specific comprehensive biomarker able to gather the different features of the disease. The fact that MR-ProANP is an independent predictor of prognosis determines its value beyond Paco2 measurement alone. Therefore, in contrast to the belief of Drs Alrajab and Uysal, MR-ProANP provides additional prognostic information for acute exacerbations of COPD. The influence of other comorbidities in MR-ProANP values might indeed integrate parameters of poor outcome performance in patients with COPD, who often suffer from several comorbidities. In this sense, the influence of comorbidities in MR-ProANP is more informative than confusing. MR-ProANP is currently a biomarker under investigation. The evaluation of a biomarker in a specific situation can elucidate the pathogenic links specific to the disease and clearly enhances our knowledge about the potential usefulness of a certain test in a specific clinical condition. Therefore, exploratory studies should be seen as the first step in the long pathway aiming to improve patient care. Whether MR-ProANP determinations have the potential to improve COPD management in the setting of severe acute exacerbation of COPD will depend on the availability of well-designed, randomized studies evaluating clinically relevant outcomes. The usefulness of the biomarker procalcitonin in guiding antibiotic therapy in lower respiratory tract infections and, particularly, in COPD, as suggested by several of our group's studies, is a perfect example of such a welcome development.3Christ-Crain M Stolz D Bingisser R et al.Procalcitonin guidance of antibiotic therapy in community-acquired pneumonia: a randomized trial.Am J Respir Crit Care Med. 2006; 174: 84-93Crossref PubMed Scopus (751) Google Scholar, 4Stolz D Christ-Crain M Bingisser R et al.Antibiotic treatment of exacerbations of COPD: a randomized, controlled trial comparing procalcitonin-guidance with standard therapy.Chest. 2007; 131: 9-19Abstract Full Text Full Text PDF PubMed Scopus (479) Google Scholar, 5Stolz D Smyrnios N Eggimann P et al.Procalcitonin for reduced antibiotic exposure in ventilator-associated pneumonia: a randomised study.Eur Respir J. 2009; 34: 1364-1375Crossref PubMed Scopus (253) Google Scholar What Is the Value of Midregional Proatrial Natriuretic Peptide in COPD Research or Clinical Practice?CHESTVol. 140Issue 2PreviewWe read with great interest the study by Bernasconi and colleagues1 published recently in CHEST (July 2011). According to the study, high midregional proatrial natriuretic peptide (MR-proANP) level was associated, as was high Paco2, with a worse 2-year survival rate compared with normal or lower values. Full-Text PDF