REVEAL: a contemporary US pulmonary arterial hypertension registry

Although a substantial amount of information about clinical pulmonary arterial hypertension (PAH) has accumulated over the past decades, there remains a need for our understanding to keep pace with the evolving milieu in which management of patients with PAH occurs. The goal of the Patient Registry for the Characterization of Primary Pulmonary Hypertension, initiated in 1981 under the sponsorship of the National Institutes of Health (NIH), was to elucidate the clinical characteristics and natural history of patients with primary pulmonary hypertension (now called idiopathic PAH; IPAH). The practical aims of the registry were to promote understanding about potential causes, facilitate early and accurate diagnosis, and develop more effective treatment strategies [1]. Analysis of the 187 patients who were enrolled from 1981 to 1985 laid a foundation of knowledge which provided the impetus for the creation of appropriate diagnostic algorithms, predictive models and the development of more effective drugs. Indeed, the importance of this undertaking has been demonstrated by its use as a basis of comparison when judging the efficacy of various treatment modalities. However, largely as a result of these advances, as well as the recognition (articulated in subsequent international symposia [2–4]) that pulmonary vascular disease is a factor in a broader spectrum of clinical contexts, the pulmonary hypertension (PH) medical community has perceived that the current understanding of this constellation of pulmonary vasculopathies requires updating and expansion. While randomised trials remain the standard for evaluating the safety and efficacy of new drugs and treatment regimens, the structured design of clinical trials is not optimal for evaluating a range of other scientific objectives. Observational studies, when consecutive enrolment is employed, do not suffer from the selection bias that exists in almost all clinical trials, allowing for a more accurate and generalisable assessment of demographics, comorbidities and disease severity. Additionally, observational studies often have larger sample sizes and longer follow-up than clinical trials, such that longterm survival curves and prognostic factors can be evaluated and in-depth analyses may be pursued in subgroups of special interest. The absence of assigned treatment choices also provides greater opportunity to include patients who may not meet the standard criteria for a disease, patients for whom little is known about characteristics and outcomes. Consequently, a number of registries have been implemented for the purpose of examining the nature of PAH in the modern era. These include databases which provide information about patients in geographically unique locations [5–10] and in individual large referral practices [11–13]. Herein, we describe the observations that have emerged to date from the largest US registry, the Registry to EValuate Early And Long-term PAH disease management (REVEAL).