Predictive value of pulmonary to systemic vascular resistance ratio in systemic lupus erythematosus patients with pulmonary arterial hypertension.

Objective: Pulmonary arterial hypertension (PAH) is a serious complication of systemic lupus erythematosus (SLE) with high mortality. The ratio of pulmonary to systemic vascular resistance (SVR) (Rp : Rs) may increase with disease progression. However, the prognostic value of Rp : Rs in predicting the outcomes of patients with SLE-PAH remains to be elucidated.

Methods: Between 1 February 2012, and 30 June 2022, consecutive patients with a diagnosis of SLE-PAH and minimum one follow-up were enrolled prospectively. The end points were all-cause mortality and lung transplantation. The predictive values of baseline clinical characteristics and hemodynamic parameters, including Rp : Rs, were analyzed using Cox proportional hazard analyses. C-statistics were used to compare the predictive ability between the models.

Results: A total of 285 patients were included and followed up for a median duration of 3.41 (interquartile range 1.81-5.72), during which 58 (20.4%) patients reached the endpoint. Multivariable Cox regression analysis revealed that in addition to the 6-minute walk distance (6MWD), the Rp : Rs was an independent predictor of the endpoint [hazard ratio 24.72; 95% confidence interval (CI) 5.59-109.29, P  < 0.001] in predicting the endpoint. The concordance index for a model incorporating the Rp : Rs and the 6MWD yielded a value of 0.75 (95% CI 0.68-0.82), which showed better predictive accuracy than the simplified risk stratification strategy. Introducing the Rp : Rs ratio to the 2022 ESC/ERS four-stratum model significantly improved its predictive performance for these patients.

Conclusion: The Rp : Rs serves as an independent predictor of adverse prognosis in patients with SLE-PAH and could provide additional value over current risk-assessment tools.