Characteristics, Prognosis, and European Society of Cardiology and European Respiratory Society Risk Stratification in Patients With Obesity and Pulmonary Arterial Hypertension

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 patients with obesity and PAH, and how well do current risk stratification tools perform in this population? Study Design and Methods: We retrospectively included patients with an incident PAH diagnosis enrolled at 10 European tertiary care centers for PAH management and compared patients with and without obesity, defined by a BMI of ≥ 30 kg/m2. Univariable and multivariable Cox regression models were fitted to assess the association between obesity and 5-year all-cause mortality. Accuracy of the European Society of Cardiology (ESC) and European Respiratory Society (ERS) risk stratification tool for the prediction of annual mortality at baseline and follow-up in patients with and without obesity was assessed by receiver operating characteristic (ROC) curve analysis. Results: Among 581 patients included (median age, 58 years [interquartile range, 41-75 years]; 61% female), 139 (24%) demonstrated obesity. Patients with obesity had more comorbidities and worse symptoms and functional capacity. Five-year crude and adjusted all-cause mortality risks were similar in patients with and without obesity. Both the 3-strata (area under the ROC curve [AUC], 0.71 [95% CI, 0.62-0.81] vs 0.64 [95% CI, 0.48-0.80]) and the 4-strata (AUC, 0.79 [95% CI, 0.69-0.89] vs 0.64 [95% CI, 0.40-0.88]) ESC and ERS risk stratification tool demonstrated lower accuracy for prediction of annual mortality in patients with obesity vs patients without obesity, although the findings were not statistically significant. However, most components of the risk stratification tool lack a significant prognostic association in patients with obesity. Interpretation: Despite the higher burden of comorbidity and the worse functional capacity, prognosis was shown to be similar in patients without obesity and with PAH. Currently recommended risk stratification strategies might not be sufficient in patients with obesity, advocating for focused research to improve risk stratification across subgroups of patients with PAH.