Clinical Heterogeneity and Outcomes of IgG4-Related Disease: Insights from a Tertiary Rheumatology Unit in Hong Kong

Background: IgG4-related disease (IgG4-RD) is a systemic fibro-inflammatory disease that can affect almost any organ throughout its course. However, its longitudinal outcomes in the Southern Chinese population remain poorly characterized. Methods: We conducted a retrospective cohort study of consecutive IgG4-RD patients from November 2018 to October 2023 at a tertiary rheumatology unit in Hong Kong. Clinical characteristics, treatment patterns and outcomes, as well as factors associated with deep organ involvement were evaluated. Results: A total of 43 IgG4-RD patients (63% male, median age at diagnosis [Formula: see text] 68) with a median follow-up duration of 3.7 years were included. Multiorgan involvement (77%) and head-and-neck-limited disease (65%) were common. Multiorgan involvement was associated with a longer diagnostic delay ([Formula: see text][Formula: see text]0.339, [Formula: see text][Formula: see text]0.032). Deep organ involvement (37%) was associated with higher median baseline neutrophil counts (5.0 vs. 4.0 × 10 9 /L, [Formula: see text][Formula: see text]0.049) and a greater number of affected organs (3 vs. 2, [Formula: see text][Formula: see text] 0.003), requiring higher induction prednisolone doses and more frequent use of steroid-sparing agents. Glucocorticoid therapy led to a clinical response in all treated patients (72%), but relapse occurred in 29% of them after a median follow-up of 61 weeks. Conclusion: In this Southern Chinese cohort, IgG4-RD frequently involved deep and multiple organs. Early recognition may help prevent the development of multisystem disease. Further studies are warranted to identify optimal management strategies for IgG4-RD in this population.