Correspondence for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: GOLD executive summary. Am J Respir Crit Care Med 2013;187:347–365. Copyright ª 2013 by the American Thoracic Society
Comorbidities and Chronic Obstructive Pulmonary Disease: Is There a Place for Lung Fibrosis? To the Editor:
We read with great interest the article by Vestbo and colleagues (1) wherein the authors provided a comprehensive summary of the recently updated Global Initiative for Chronic Obstructive Lung Disease guidelines for disease diagnosis and management. According to this statement, chronic obstructive pulmonary disease (COPD) may coexist with several other conditions called comorbidities, which have a detrimental impact on disease prognosis and sometimes are overlooked because primary symptoms often overlap with those of the baseline condition; that is, breathlessness may also characterize lung cancer and congestive heart failure. Although the authors reported a variety of other conditions that may coexist with COPD, including lung cancer, cardiovascular diseases, depression, hypertension, and osteoporosis, they left out lung fibrosis, a disease entity that often coexists with obstructive lung disease in the context of combined pulmonary fibrosis and emphysema (CPFE) syndrome and significantly affects patients’ survival. Traditionally regarded as separate disease states, the combination of both processes was originally defined by Cottin and colleagues (2) as a syndrome characterized by frequent paraseptal emphysema with upper zone predominance, lower lobe fibrosis (mainly of the usual interstitial pneumonia pattern), relatively preserved lung volumes contrasting with disproportionally impaired gas exchange, and severe exercise hypoxemia. The exact prevalence of CPFE is still debatable, with current studies reporting that almost a third of patients with lung fibrosis present with upper lobe emphysema (2). Limited, but interesting, epidemiological data report a high prevalence (8.9%) of CPFE in patients with lung cancer (3). On the contrary, it is currently unknown how many patients with COPD and of what stage of disease severity present with imaging features compatible with lung fibrosis, as well as the exact contribution of this coexistence in patients’ prognosis. Despite intense research efforts and several important discoveries in the pathogenesis of both lung fibrosis and emphysema, there is a major lack of knowledge regarding pathogenic schemes that encompass both disease entities. Noxious activity of cigarette smoke oxidative injury and accelerated senescence of pulmonary parenchyma represent a rather simplistic pathogenic model that could explain both destruction of lung parenchyma and aberrant wound healing characteristic of emphysema and lung fibrosis (4), respectively. Nevertheless, the complexity of the pathogenic network has not been yet delineated, with an increasing body of evidence involving autoimmunity and loss of immune tolerance within the etiologic algorithm (5). In addition, it is important to emphasize the fact that although other comorbidities present with therapeutic regimens of established efficacy, there is still no effective treatment for CPFE, evidence that mainly arises from the
limited therapeutic options in patients with idiopathic pulmonary fibrosis and the lack of clinical trials including patients with emphysema coexisting with lung fibrosis. The above statement is crucial because patients with CPFE have been reported as having a median survival of 63–70 months, a prognosis more favorable than that of idiopathic pulmonary fibrosis (35 mo) (6), but far worse than that of emphysema (100% 2-yr survival in patients with FEV1 above one-third of predicted). Pulmonary hypertension is the most prevalent complication of the natural course of the syndrome, as it is associated with worse clinical outcomes (2). Although it has a characteristic functional and radiological profile, it is still debatable whether CPFE represents a distinct syndrome or a coincidence of pulmonary fibrosis with emphysema for the following reasons: (1) no common pathogenic mechanisms have been proposed to encompass both disease entities, and (2) there is no robust evidence that a syndrome has either prognostic or management significance that will alter current recommendations. The main scope of this letter is to shed further light onto the coexistence of lung fibrosis and COPD, capturing clinicians’ interest in better defining CPFE and determining the exact prevalence of this syndrome that is worryingly increasing. This will trigger future clinical trials that will distinctly include patients with CPFE, thus allowing an accurate interpretation of the therapeutic potential of novel specifically targeted pharmacologic agents. Author disclosures are available with the text of this letter at www.atsjournals.org.
Argyris Tzouvelekis, M.D., Ph.D. Nikolaos Siafakas, M.D., Ph.D. Demosthenes Bouros, M.D., Ph.D. Democritus University of Thrace Alexandroupolis, Greece and University of Crete Crete, Greece References 1. Vestbo J, Hurd SS, Agustí AG, Jones PW, Vogelmeier C, Anzueto A, Barnes PJ, Fabbri LM, Martinez FJ, Nishimura M, et al. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: GOLD executive summary. Am J Respir Crit Care Med 2013;187:347–365. 2. Cottin V, Nunes H, Brillet PY, Delaval P, Devouassoux G, Tillie-Leblond I, Israel-Biet D, Court-Fortune I, Valeyre D, Cordier JF; Groupe d’Etude et de Recherche sur les Maladies Orphelines Pulmonaires (GERM O P). Combined pulmonary fibrosis and emphysema: a distinct underrecognised entity. Eur Respir J 2005;26:586–593. 3. Usui K, Tanai C, Tanaka Y, Noda H, Ishihara T. The prevalence of pulmonary fibrosis combined with emphysema in patients with lung cancer. Respirology 2011;16:326–331. 4. Chilosi M, Poletti V, Rossi A. The pathogenesis of COPD and IPF: distinct horns of the same devil? Respir Res 2012;13:3. 5. Tzouvelekis A, Zacharis G, Oikonomou A, Mikroulis D, Margaritopoulos G, Koutsopoulos A, Antoniadis A, Koulelidis A, Steiropoulos P, Boglou P, et al. Increased incidence of autoimmune markers in patients with combined pulmonary fibrosis and emphysema. BMC Pulm Med 2013;13:31. 6. Raghu G, Collard HR, Egan JJ, Martinez FJ, Behr J, Brown KK, Colby TV, Cordier JF, Flaherty KR, Lasky JA, et al.; ATS/ERS/JRS/ALAT Committee on Idiopathic Pulmonary Fibrosis. An official ATS/ERS/ JRS/ALAT statement: idiopathic pulmonary fibrosis: evidence-based guidelines for diagnosis and management. Am J Respir Crit Care Med 2011;183:788–824. Copyright ª 2013 by the American Thoracic Society