Sicong Li,* Luyang Gao,* Sicheng Zhang,* Qing Zhao, Tao Yang, Anqi Duan, Yijia Wang, Qi Wang, Zhihui Zhao, Qin Luo, Zhihong Liu

Center for Respiratory and Pulmonary Vascular Diseases, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Zhihong Liu; Qin Luo, Email zhihongliufuwai@163.com; luoqin2009@163.com

Background: Composite inflammatory markers, such as the systemic inflammatory response index (SIRI), are associated with the severity and progression of several cardiovascular diseases. However, the relationship between SIRI and chronic thromboembolic pulmonary hypertension (CTEPH) remains unclear. We hypothesized that elevated SIRI levels would correlate with disease severity and independently predict adverse clinical outcomes in patients with CTEPH. This study aimed to clarify the predictive value of SIRI in patients with CTEPH.
Methods: This retrospective cohort study included 383 patients with CTEPH treated at Fuwai Hospital between June 2013 and June 2021. Receiver operating characteristic (ROC) curve analysis was used to compare the diagnostic performance of SIRI to other inflammatory indices and identify the optimal cutoff value. Kaplan-Meier analysis and Cox proportional hazard models were used to examine the relationship between SIRI and clinical worsening.
Results: During a mean follow-up period of 30.6 months, 79 participants experienced clinical worsening. The SIRI was significantly correlated with established markers of CTEPH severity, including the 6-minute walk distance, N-terminal pro-brain natriuretic peptide, and hemodynamic parameters. Kaplan–Meier curve revealed that individuals with a SIRI ≥ 0.80 exhibited significantly poorer survival rates and a shorter time to clinical worsening compared to those with a SIRI < 0.80 (P < 0.01). Adjusted Cox proportional hazards analysis revealed that SIRI remained an independent predictor of clinical worsening (hazard ratio (HR) 2.033; 95% confidence interval (CI) 1.227– 3.370). ROC analysis revealed that SIRI exhibited the highest area under the curve value of 0.730 (95% CI 0.659– 0.810). Incorporating SIRI into The COMPERA 2.0, the risk score improved its predictive value for adverse outcomes in patients with CTEPH.
Conclusion: SIRI is a valuable prognostic marker for CTEPH, correlating with established markers of disease severity and independently predicting clinical worsening. SIRI provides additional prognostic predictive value when used in conjunction with the risk score of COMPERA 2.0.

Keywords: chronic thromboembolic pulmonary hypertension, prognosis, risk factors, inflammation