IgG4-related disease (IRD) is a multisystem disease where raised serum IgG4 may predict relapse and multiorgan involvement.1 The aim of this study was to compare demographics, multi-organ involvement, response to treatment, relapse rate and end organ damage in patients with versus those without a raised serum IgG4 level at the point of diagnosis.Methods
Patients diagnosed with IgG4 disease between January 2005 and September 2016 according to the ICD Criteria formed the study population. Patients were divided into two groups – Group 1: patients with elevated serum IgG4 and Group 2: normal serum IgG4. Patients’ demographics, other organs involvement, response to steroid treatment, relapse rate and long-term complications (organ dysfunction, exocrine and endocrine insufficiency) were compared between the 2 groups. For this study, we analysed the data based on 2 levels of IgG4 A:>than upper limit of normal and B: Twice the upper limit of normal as reported in literature.1 The patients were followed up for at least 12 months from the time of diagnosis.Results
Of the 47 patients identified, 31 (66%) patients had elevated serum IgG4 at diagnosis. There was no statistically significant difference between the 2 groups in age (median age 66 vs 63, p=0.116) and sex (male 85.7% vs 58.8%, p=0.072); other organs involvements (85.7% vs 94.1%, p=0.635), response to steroids (92.6% vs 87.5%, p=0.062), relapse rate (32.1% vs 11.8%, p=0.165) and organ dysfunction (10.7% vs 5.9%, p=1.0).When the serum IgG4 cut-off was twice the upper limit of normal (ULN), more patients had exocrine insufficiency (78.9% vs 46.2%, p=0.035). However other organs involvement (89.4% vs 88.5%, p=1.0), response to steroids (94.4% vs 88.0%, p=0.628), relapse rate (36.8% vs 15.4%, p=0.160), organ dysfunction (10.5% vs 7.5%, p=1.0) and endocrine insufficiency (42.1% vs 46.2%, p=0.973) showed no statistically significant difference. Median follow-up was 40 months (range 12–140 months).Conclusions
This single centre observational study shows that a raised serum IgG4 at the point of diagnosis greater than ULN did not affect prognosis in patients with IRD. However a raised serum IgG4 greater than two times the ULN was significantly associated with pancreatic exocrine insufficiency and relapse in patients with IgG4-RD. Larger multicentre studies with longer follow-up are required to corroborate these findings and define the role and cut-off value of serum IgG4 in outcomes of IgG4-RD.