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Updated: Jun 2, 2026
Imaging Features of Systemic Sclerosis-Associated Interstitial Lung Disease
Published on: June 16, 2020
Association of initial diagnostic setting and referral delay with mortality in systemic sclerosis: a nationwide
Chingching Foocharoen1, Wilaiporn Thinkhamrop2, Ajanee Mahakkanukrauh1
1Department of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand.
Background:
Early diagnosis and prompt referral are critical for improving outcomes in systemic sclerosis (SSc), yet disparities in diagnostic capabilities between healthcare levels may delay treatment and impact survival. This study aimed to compare mortality risk among SSc patients based on their diagnostic pathway: initial diagnosis at a secondary care hospital before referral versus prompt referral and diagnosis at a tertiary center.
Methods:
Using National Health Security Office cohort data (fiscal years 2016-2023), we identified 17,036 patients aged ≥ 18 years with SSc (ICD-10 M34) diagnosed at tertiary or university hospitals. The primary outcome was mortality risk through December 31, 2024. Mortality rates (95% CI) were stratified by the initial diagnostic facility. Cox regression analysis with a time-dependent interaction term for age was used to evaluate factors associated with mortality.
Results:
A total of 4,404 patients with SSc from 102 tertiary care hospitals were referred from secondary care hospitals. Patients first diagnosed at secondary care hospitals exhibited a significantly higher mortality rate (0.89 per 100 person-months; 95% CI 0.85-0.93) compared to those first diagnosed at tertiary care hospitals (0.67 per 100 person-months; 95% CI 0.65-0.69; p < 0.001). Increased mortality risk was associated with older age (HR 1.055), referral duration > 180 days vs. ≤ 7 days (HR 1.300), acute myocardial infarction (HR 1.895), and primary pulmonary hypertension (HR 1.654). An interaction between age and log(time) demonstrated that the effect of age on mortality decreased by approximately 0.5% per month of follow-up.
Conclusion:
The initial diagnosis of SSc at tertiary care hospitals was associated with a better prognosis than that at secondary care hospitals. A longer referral duration was associated with poorer survival. Advanced age and coexisting cardiopulmonary diseases were significantly associated with mortality in patients with SSc. These findings highlight the need for standardized referral criteria and "red flag" checklists to facilitate earlier specialized care.
