Evaluation of the European Society of Cardiology/European Respiratory Society derived three- and four-strata risk stratification models in pulmonary arterial hypertension: introducing an internet-based risk stratification calculator

Aims: Estimation of prognosis in pulmonary arterial hypertension (PAH) has been influenced by that various risk stratification models use different numbers of prognostic parameters, as well as the lack of a comprehensive and time-saving risk assessment calculator. We therefore evaluated the various European Society of Cardiology (ESC)-/European Respiratory Society (ERS)-based three- and four-strata risk stratification models and established a comprehensive internet-based calculator to facilitate risk assessment. Methods and results: Between 1 January 2000 and 26 July 2021, 773 clinical assessments on 169 incident PAH patients were evaluated at diagnosis and follow-ups. Risk scores were calculated using the original Swedish Pulmonary Arterial Hypertension Registry (SPAHR)/Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA) three-strata model, the updated SPAHR three-strata model with divided intermediate risk, and the simplified three-parameter COMPERA 2.0 four-strata model. The original SPAHR/COMPERA and the updated SPAHR models were tested for both 3-6 and 7-11 available parameters, respectively. Prognostic accuracy [area under the receiver operating characteristic (ROC) curve (AUC)] and Uno's cumulative/time-dependent C-statistics (uAUC) were calculated for 1-, 3-, and 5-year mortality. At baseline, both the original SPAHR/COMPERA and the updated SPAHR models, using up to six parameters, provided the highest accuracy (uAUC = 0.73 for both models) in predicting 1-, 3-, and 5-year mortality. At follow-ups, the updated SPAHR model with divided intermediate risk (7-11 parameters) provided the highest accuracy for 1-, 3-, and 5-year mortality (uAUC = 0.90), followed by the original SPAHR/COMPERA model (7-11 parameters) (uAUC = 0.88) and the COMPERA 2.0 model (uAUC = 0.85). Conclusions: The present study facilitates risk assessment in PAH by introducing a comprehensive internet-based risk score calculator (https://www.svefph.se/risk-stratification). At baseline, utilizing the original or the updated SPAHR models using up to six parameters was favourable, the latter model additionally offering sub-characterization of the intermediate risk group. Our findings support the 2022 ESC/ERS pulmonary hypertension guidelines' strategy for risk stratification suggesting the utilization of a three-strata model at baseline and a simplified four-strata model at follow-ups. Our findings furthermore support the utility of the updated SPAHR model with divided intermediate risk, when a more comprehensive assessment is needed at follow-ups, complementing the three-parameter COMPERA 2.0 model. Larger multi-centre studies are encouraged to validate the utility of the updated SPAHR model. Take home message: By introducing an internet-based risk score calculator (https://www.svefph.se/risk-stratification), risk assessment is facilitated. Our results support the 2022 ESC/ERS pulmonary hypertension guidelines' risk stratification strategy, additionally suggesting the updated SPAHR three-strata model with divided intermediate risk, as a promising complement to the new simplified three-parameter COMPERA 2.0 four-strata strategy, when a more comprehensive overview is needed.