Performance of risk stratification scores and role of comorbidities in older vs younger patients with pulmonary arterial hypertension

Background: Risk scores are important tools for the prognostic stratification of pulmonary arterial hypertension (PAH). Their performance and the additional impact of comorbidities across age groups is unknown. Methods: Patients with PAH enrolled from 2001 to 2021 were divided in ≥65 years old vs <65 years old patients. Study outcome was 5-year all-cause mortality. French Pulmonary Hypertension Network (FPHN), FPHN noninvasive, Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA) and Registry to Evaluate Early and Long-term PAH Disease Management (REVEAL 2.0) risk scores were calculated and patients categorized at low, intermediate and high risk. Number of comorbidities was calculated. Results: Among 383 patients, 152 (40%) were ≥65 years old. They had more comorbidities (number of comorbidities 2, IQR 1-3, vs 1, IQR 0-2 in <65 years patients). Five-year survival was 63% in ≥65 vs 90% in <65 years. Risk scores correctly discriminated the different classes of risk in the overall cohort and in the older and younger groups. REVEAL 2.0 showed the best accuracy in the total cohort (C-index 0.74, standard error-SE- 0.03) and older (C-index 0.69, SE 0.03) patients, whereas COMPERA 2.0 performed better in younger patients (C-index 0.75, SE 0.08). Number of comorbidities was associated with higher 5-year mortality, and consistently increased the accuracy of risk scores, in younger but not in older patients. Conclusions: Risk scores have similar accuracy in the prognostic stratification of older vs younger PAH patients. REVEAL 2.0 had the best performance in older patients and COMPERA 2.0 had it in younger patients. Comorbidities increased the accuracy of risk scores only in younger patients.