Incorporation of renal function in mortality risk assessment for pulmonary arterial hypertension

Abstract

Risk assessment is important for prognostication and individualized treatment decisions for patients with pulmonary arterial hypertension (PAH). The purpose was (1) to compare contemporary risk assessment tools and (2) to determine the prognostic significance of risk parameters of kidney function and whether they can further improve risk prediction for patients with PAH. We identified a cohort of treatment-naive patients (n = 211) who received an incident diagnosis of PAH at the University of Ottawa Heart Institute. Using demographics, disease characteristics, and hemodynamic data at diagnosis, we categorized patients as low, intermediate, or high risk according to current European guidelines (European Society of Cardiology [ESC]) and registry to evaluate early and long-term pulmonary arterial hypertension disease management (REVEAL) risk scores. The primary end-point was transplant-free survival (TFS). Patients were predominantly women (64.6%) with World Health Organization function Class III symptoms (66.5%). The median TFS was 7.09 years. There was little agreement between ESC- and REVEAL-based risk estimates (weighted kappa = 0.21-0.34). Although both the ESC (log-rank, p = 0.0002) and REVEAL algorithms stratified TFS risk (p < 0.0001), the REVEAL score provided superior discrimination (C-statistic = 0.70 vs 0.59, p = 0.004). Renal function at diagnosis (p < 0.0001) and Δ renal function at 6 months (p < 0.0001) were identified as novel risk parameters and served to reclassify some patients in the intermediate-risk category to a lower or higher risk stratum (p < 0.0001). REVEAL-based strategies provide superior TFS risk discrimination to ESC/European Respiratory Society-based approaches. However, the classification of intermediate-risk patients varied significantly across tools. We demonstrate the importance of renal function, which further improved the stratification of risk in patients with PAH, particularly in patients who are considered intermediate risk.