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
Authors: Ahmed Abdulla , Ahmed Salaheldin , Kempe Daniel , Rådegran Göran 
Published: February 2023

Abstract

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.