Clinical characteristics of IgG4-related respiratory disease patients: a large Chinese cohort study

OBJECTIVES: IgG4-related disease (IgG4-RD) is an autoimmune disorder and frequently involves multiple organs. The respiratory tract is one of the most frequently affected sites. In this study, we aimed to compare the demographic and clinical characteristics between IgG4 related respiratory disease (IgG4-RRD+) and extra-thoracic IgG4-related disease (IgG4-RRD-) in a large cohort. METHODS: A total of 448 cases of IgG4-RD (104 IgG4-RRD+ patients and 344 IgG4-RRD- patients) diagnosed at Peking University People's Hospital during 2003 to 2020 were included in our study. Patients' demographic data, clinical characteristics, laboratory parameters and imaging features were analysed. RESULTS: IgG4-RRD+ patients had an older age at disease onset and diagnosis. Multiorgan involvement and hypocomplementaemia were more common in IgG4-RRD+. Besides, the level of ESR, IgG and IgG4 were higher in IgG4-RRD+ patients. In IgG4-RRD+ group, salivary gland, lacrimal gland, lymph nodes, biliary system and kidney were more commonly involved than those in the IgG4-RRD- group. Also, more organ involvement eosinophilia and biliary involvement were independent risk factors for the development of IgG4-RRD+. CONCLUSIONS: Our study revealed demographic, clinical and laboratory differences between the two phenotypes, in addition to describing the imaging features of IgG4-RRD+, which will be helpful for understanding of the disease.