Characteristics, Prognosis and ESC/ERS Risk Stratification in Obese Patients with Pulmonary Arterial Hypertension (PAH)

Background: The impact of obesity on pulmonary arterial hypertension (PAH) remains largely underexplored, with excess weight potentially masking symptoms and affecting the reliability of current risk stratification tools. Research question: What are the clinical characteristics and prognosis of obese patients with PAH, and how well do current risk stratification tools perform in this population? Study design and methods: We retrospectively included patients with incident PAH diagnosis enrolled at ten European tertiary care centers for PAH management and compared patients with and without obesity, defined by a BMI ≥30 kg/m2. Uni- and multivariable Cox regression models were fitted to assess the association between obesity and 5-years all-cause mortality. Accuracy of the ESC/ERS risk stratification tool for the prediction of annual mortality at baseline and follow up in patients with and without obesity was assessed by ROC curve analysis. Results: Among 581 patients included (median age 58 years, IQR 41-75; 61% females), 139 (24%) were obese. Obese patients had more comorbidities and worse symptoms/functional capacity. 5-years crude and adjusted all-cause mortality risk was similar in obese and non-obese. Both the three- (AUC 0.71, 95% CI 0.62-0.81 vs 0.64, 95%CI 0.48-0.80) and the four-strata (AUC 0.79 95% CI 0.69-0.89 vs 0.64 95% CI 0.40-0.88) ESC/ERS risk stratification tool demonstrated lower accuracy for prediction of annual mortality in obese vs non-obese patients, although not statistically significant. However, most components of the risk stratification tool lack a significant prognostic association in obese patients. Interpretation: Despite the higher burden of comorbidity and the worse functional class, prognosis is similar in obese compared with non-obese patients with PAH. Currently recommended risk stratification strategies might not be sufficient in patients with obesity claiming for focused research to improve risk stratification across subgroups of patients with PAH.