Abstract
Risk stratification of pulmonary arterial hypertension based on the number of noninvasive low-risk criteria achieved at first follow-up provides an accurate identification of patients with an excellent prognosis http://ow.ly/IyNI30irqpK
From the authors:
We read with interest the correspondence by M.M. Hoeper and colleagues regarding risk assessment in pulmonary arterial hypertension (PAH). This follows the three manuscripts on the topic published in 2017 in the European Respiratory Journal [1, 2] and in the European Heart Journal [3]. All utilised a risk-assessment method derived from the risk-stratification table proposed by the 2015 European Society of Cardiology/European Respiratory Society Guidelines for the diagnosis and treatment of pulmonary hypertension [4, 5].
Two different methods were utilised to assess risk in large cohorts of patients with PAH. In their respective registries, Kylhammar et al. [3] and Hoeper et al. [2] calculated an averaged risk by assigning a score of 1, 2 or 3 for each criterion according to the level of risk (1 for a low-risk, 2 for an intermediate-risk and 3 for a high-risk criterion). Then, the sum of the score obtained was divided by the number of available variables for each patient and was rounded off to the nearest integer, defining an individual risk score corresponding to the patient's risk group (1, 2 or 3, for low, intermediate or high risk, respectively) [2, 3]. In the French registry, our approach consisted of counting the number of low-risk criteria present at baseline and then achieved at first follow-up [1]. Two models were analysed in our study. In the first model, four variables were taken into account: New York Heart Association (NYHA)/World Health Organization (WHO) functional class, 6-min walking distance (6MWD), right atrial pressure and cardiac index measured by right-heart catheterisation. The second model was one using only the presence or the achievement of three noninvasive low-risk criteria: NYHA/WHO functional class I–II, 6MWD >440 m and N-terminal pro-brain natriuretic peptide (NT-proBNP) <300 ng·L−1 or brain natriuretic peptide (BNP) <50 ng·L−1. In both models, with increasing number of low-risk criteria achieved at first follow-up evaluation, transplant-free survival was better [1].
In their correspondence, M.M. Hoeper and colleagues also utilised the French registry methodology [1] for the risk assessment of patients with PAH enrolled in the COMPERA registry. This study represents an external validation of the use of three simple noninvasive low-risk criteria to identify patients with idiopathic PAH having an excellent long-term prognosis (5-year survival rate of 95%).
We recently performed additional analyses in our cohort to determine the validity of our two models. We determined the index of concordance by Harrell's c-index in the model with four variables (including invasive haemodynamic parameters) and in the model that included three noninvasive variables [6]. Values for the c-index were higher than 0.7 for the models based on variables at first follow-up, indicating that our two models are strong: Harrell's c-index of 0.72 for the invasive model and 0.74 for the noninvasive one. However, for the multivariable analysis based on variables present at baseline, concordance was less strong, with a Harrell's c-index of 0.61 for the invasive model. These results confirm that low-risk criteria achieved at first follow-up were more discriminant for predicting survival than those present at baseline.
To conclude, our study and the analyses performed in the COMPERA registry confirm that our approach of risk stratification based on the number of noninvasive low-risk criteria achieved at first follow-up provides an accurate identification of patients with an excellent prognosis. The achievement of the three noninvasive low-risk criteria (NYHA/WHO class I–II, 6MWD >440 m and NT-proBNP <300 ng·L−1 or BNP <50 ng·L−1) could be considered as a treatment goal in patients with PAH. However, only few patients reached those three low-risk criteria at first follow-up (9% in the COMPERA cohort and 19% in the French cohort). Those results suggest that there is still more to be done to obtain a greater proportion of patients reaching all low-risk criteria.
Footnotes
Conflict of interest: A. Boucly reports personal fees and non-financial support from Actelion, and non-financial support from GlaxoSmithKline and Merck, outside the submitted work.
Conflict of interest: J. Weatherald reports grants from the European Respiratory Society and the Canadian Thoracic Society, during the conduct of the study, as well as personal fees and non-financial support from Actelion Pharmaceuticals and non-financial support from Bayer, for travel to scientific meetings outside the submitted work.
Conflict of interest: M. Humbert reports grants, personal fees and non-financial support from Actelion, Bayer, GlaxoSmithKline and Merck, and personal fees from Arena and Novartis, all outside the submitted work.
Conflict of interest: O. Sitbon reports grants, personal fees and non-financial support from Actelion, Bayer, GlaxoSmithKline and Merck, and personal fees from Arena, all outside the submitted work.
- Received February 6, 2018.
- Accepted February 7, 2018.
- Copyright ©ERS 2018