Introduction: Systemic sclerosis related pulmonary arterial hypertension (SScPAH) is characterized by a worse prognosis in comparison to idiopathic pulmonary arterial hypertension (IPAH). The estimated mortality risk reported in the current European guidelines for pulmonary hypertension has been evaluated mostly in IPAH patients. The aim of this study was to explore the ability of the risk assessment proposed in the guidelines to predict long-term mortality in SScPAH patients.
Methods: The study population constituted patients diagnosed with SScPAH and prospectively enrolled in the Johns Hopkins Pulmonary Hypertension Program from 2000-2016. Patients with assessment of WHO functional class, 6-minute walking distance (6MWD), and right heart catheterization measurements at diagnosis were included in the analysis. A Cox proportional hazards model was used to examine the adjusted hazard ratio (HR) of mortality for each of the following four low-risk criteria: WHO functional class I-II, 6MWD >440m, right atrial pressure <8mmHg, and cardiac index ≥2.5L/min/m2. A Kaplan-Meier curve was plotted to describe overall survival at 5 years.
Results: 151 patients (mean age 61.2, 84.8% female) were included in the analysis. Over a mean follow-up period of 4.9 years, 87 patients (57.6%) died. In Cox proportional hazards multivariate analysis, the HR (95%CI) of mortality compared to the presence of no low-risk criteria was 0.65 for one criterion (0.37-1.15), 0.34 for two (0.17-0.68), 0.16 for three (0.06-0.44), and 0.10 for four (0.01-0.78). Figure 1 describes the 5-year survival according to the number of criteria.
Conclusion: Our study highlights that only a small proportion of SScPAH patients are diagnosed at an early stage of PAH disease, suggesting the need of more intense PAH screening programs for this population. Current guidelines for risk assessment in IPAH patients can also be helpful in SScPAH patients, particularly in identifying patients at higher risk of mortality.