© 2006 American Thoracic Society
The Need for National Registries in Rare DiseasesFrom the Authors:We thank Souza and colleagues for their comments on our recent article (1). One of our goals was to describe the clinical, functional, and hemodynamic characteristics for pulmonary arterial hypertension (PAH) in a 1-year period (from October 2002 to October 2003). Approximately half the cases corresponded to idiopathic, familial, and anorexigen-associated PAH, and half were associated with various diseases (connective tissue diseases, congenital heart disease, portal hypertension, and HIV infection). The true burden of pulmonary hypertension in France is certainly much higher, as the French registry focused on PAH only, therefore excluding patients with pulmonary hypertension due to more common conditions such as chronic hypoxemia and thromboembolic pulmonary disease (2). Importantly, pulmonary hypertension may complicate prevalent conditions in other parts of the world. As stated by Souza and coworkers in their letter, recent information indicates that schistosomiasis is a major cause of pulmonary hypertension in Brazil, as well as in other developing countries, highlighting the need for specific research and care in this area (3). Other risk factors, including sickle cell disease (4), HIV infection (5), and drug exposure (5), may also contribute to the burden of the condition in many countries. Recent reports indicate that pulmonary hypertension is a significant complication of sickle cell disease, underlining the need for specific studies to better characterize and treat these patients (4). Moreover, the prevalence of PAH in HIV-infected subjects is around 0.5% in France and Switzerland, suggesting that it may indeed cause large numbers of (mostly unrecognized) cases in many countries (5). Finally, exposure to fenfluramine derivatives was a major PAH risk factor in France in the 1980s–1990s. On the basis of this information, health authorities withdrew these drugs from the market in the late 1990s (5). This information underlines the need for registries in various parts of the world where pulmonary hypertension may have distinct recognized or as yet unrecognized causes (1–5). Efforts to better screen and characterize patients with pulmonary hypertension in well-designed registries taking into account local specificities should allow better recognition of risk factors and provide useful information to health authorities. This should also improve our understanding of the pathophysiology of this complex condition, as well as allow earlier diagnosis and better patient management (6). Importantly, the Global Alliance against chronic Respiratory Diseases (GARD: http://www.who.int/respiratory/gard/en/) has clearly stated that a World Health Organization program for the awareness of pulmonary hypertension would be useful, indicating that the burden of pulmonary hypertension is now recognized by health authorities. Thus, it is timely to provide worldwide epidemiological information on this condition.
Hôpital Antoine-Béclère, Assistance-Publique-Hôpitaux de Paris, Université Paris-Sud 11, Clamart, France FOOTNOTES Conflict of Interest Statement: Neither author has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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