Supplementary Material for: Clinical features and survival in Fibrosing Mediastinitis: a multicenter cohort study

Introduction: Fibrosing mediastinitis (FM)—also known as mediastinal fibrosis or sclerosing mediastinitis—is a rare, benign, but potentially life-threatening disorder of unclear etiology. This study aimed to evaluate the clinical characteristics, geographic distribution, and long-term survival of patients with FM and to identify prognostic factors for all-cause mortality. Methods: Of 215 patients screened, 192 were diagnosed with FM and included in the final cohort. The clinical characteristics and survival of patients with FM were reported. Prognostic factors were evaluated by Cox regression model. Results: The mean age of FM patients was 66.6 ± 13.4 years. Geographic clustering was evident in northwestern China. Compared with survivors, deceased patients showed higher rates of edema (50.0% vs. 22.3%, P = 0.016), lower serum cholesterol (3.8 ± 0.8 mmol/L vs. 4.5 ± 1.1 mmol/L, P = 0.004), and elevated NT-proBNP (751.8 pg/mL vs. 220.5 pg/mL, P = 0.001). Echocardiography indicated more severe right ventricular remodeling in the deceased group. Chest CT commonly revealed bilateral mediastinal involvement (85.4%), lobar vascular compression, and mediastinal lymphadenopathy (88.5%). Over a median follow-up of 23 months, the 1-, 3-, and 5-year survival rates were 94.5%, 86.3%, and 84.6%, respectively. Right heart failure was the leading cause of death (50%). Multivariable Cox analysis identified smoking (HR 4.32, 95% CI 1.61–11.62, P = 0.004) and elevated systolic pulmonary artery pressure (sPAP) (HR 1.02 per mmHg, 95% CI 1.01–1.03, P = 0.017) as independent predictors of all-cause mortality. FM-related deaths were more strongly associated with current smoking (HR 15.18, P < 0.001), presence of pleural effusion (HR 5.10, P = 0.03), and elevated sPAP (HR 1.02 per mmHg, P = 0.011). Conclusion: FM predominantly affects older adults and is geographically clustered in northwestern China. Smoking and elevated sPAP are key prognostic indicators for mortality. Despite substantial cardiopulmonary impairment, long-term survival remains relatively favorable.