Immunoglobulin G4-related disease (IgG4-RD) is a chronic condition characterized by inflammation and fibrosis within multiple organs. This study aimed to evaluate the mortality burden of IgG4-RD in a large Chinese cohort.

Data were collected from a prospective IgG4-RD cohort from Peking Union Medical College Hospital between 2012 and 2026. Telephone follow-up was conducted to ascertain survival status and supplement missing clinical data. Mortality was compared with that of the general population in China using the standardized mortality ratio (SMR). Causes of death, as well as treatment and relapse information, were also reviewed in patients who died during follow-up.

Survival information was available for 1,278 patients with IgG4-RD, with a median follow-up of 77 months. During follow-up, 45 patients (3.5%) died. The overall SMR showed that patients with IgG4-RD had a 1.5-fold higher risk of death than the general population in China. Excess mortality was observed in both male and female patients (male: 1.44, 95% CI 1.02 to 2.00; female: 2.01, 95% CI 1.14 to 3.63). Patients aged ≥60 years had a significantly increased risk of death compared with the general population (1.73, 95% CI 1.27 to 2.36), whereas no significant increase was observed in those aged <60 years (0.83, 95% CI 0.34 to 1.99). Causes of death included infection, organ failure attributable to primary disease, malignancy, cardiovascular disease, and other causes (Figure 1). Infection was the leading cause of death, followed by organ failure related to primary disease and malignancy. In addition, four patients died of intracerebral hemorrhage and four of acute myocardial infarction. Baseline clinical characteristics, treatment exposure, and relapse status were also reviewed among deceased patients.

IgG4-RD is associated with excess long-term mortality in China, particularly among older patients, with infection emerging as the leading cause of death. Greater awareness across specialties and closer monitoring for severe infection, organ failure, and malignancy may help improve long-term outcomes in IgG4-RD.