Pulmonary and Critical Care Updates Update in Pulmonary Arterial Hypertension 2007

Until recently, information relating to the epidemiology of PAH has been derived from a single National Institutes of Health (NIH) registry conducted in the United States in the early 1980s, in which 187 patients with idiopathic PAH were described and followed for up to 5 years (3, 4). Prompted by the rapid evolution of knowledge in the field of PAH and the absence of any new multicenter registry since the 1980s, prospective registries were initiated in France (5), Scotland (6), and the United States (7). In the French registry, around half of 674 PAH cases occurred in patients with comorbid conditions (connective tissue diseases, congenital heart diseases, portal hypertension, HIV infection, and exposure to drugs and toxins, such as fenfluramine derivatives) (5). The other half had no identifiable risk factor, corresponding to idiopathic (sporadic) or familial PAH (5). Patients managed in referral centers in France in 2002/2003 were detected late in the course of the disease, with a majority of patients displaying severe functional and hemodynamic compromise: at diagnosis, 12, 63, 24, and 1% of patients were in New York Heart Association (NYHA) functional classes IV, III, II, and I, respectively (5). The lowest estimate of prevalence of PAH in France was 15 cases per million adult inhabitants (5). Of note, there was wide variation in PAH prevalence in the French dataset, with higher prevalence (25 cases per million) in the Paris area, the region with the largest pulmonary vascular center (5). In Scotland, ‘‘administrative’’ hospitalization data as well as ‘‘expert’’ information from the Scottish Pulmonary Vascular Unit were evaluated (6). When analyzing national hospitalization records, a prevalence of 52 PAH cases per million was obtained, but the robustness of PAH diagnosis was questionable (6, 8). Conversely, expert data based on gold-standard diagnostic procedures indicated a prevalence of 26 cases per million (6). These contemporary studies provide an estimate of the minimum (French expert centers) and near-maximum (Scottish hospitalization records) prevalence of PAH, confirming that PAH is a rare but certainly underestimated condition (8). A United States–based registry from a single large referral center in Chicago established that patients with PAH are referred late to specialized centers in the United States, with 80% in NYHA class III or IV (7). This registry also emphasized that medical management is often inappropriate, with an excessive use of oral calcium channel blockers in patients with PAH showing no acute vasodilator response (7, 9). Finally, it was apparent from this registry that referral of patients with PAH with connective tissue diseases (mainly systemic sclerosis) was increasing, whereas referral of HIV-infected patients remained low (7). This latter feature is markedly different from the French registry (5) and presumably indicates the underappreciation of PAH in HIVinfected patients in the United States. This single tertiary center registry may not reflect national trends in the United States, which might be better analyzed through data provided by the Registry to Evaluate Early and Long-Term Disease Management (REVEAL) registry, a multicenter, observational, industry-sponsored United States–based registry currently enrolling patients.