Demographics and key covariates according to IgG4-RD phenotype groups (derivation cohort)
| Covariate | Group 1 ‘Pancreato-Hepato-Biliary’ | Group 2 ‘Retroperitoneum and Aorta’ | Group 3 ‘Head and Neck-Limited’ | Group 4 ‘Mikulicz and Systemic’ |
| Female (%) | 21% | 25% | 76% | 22% |
| Asian (%) | 37% | 25% | 67% | 52% |
| Age at diagnosis (year, mean, SD) | 63 (13) | 58 (16) | 55 (13) | 63 (13) |
| Time to diagnosis (year, mean, SD) | 0.9 (1.8) | 1.8 (4.0) | 2.3 (3.4) | 2.0 (3.6) |
| Serum IgG4 concentration (mg/dL, median, IQR) | 316 (147–622) | 178 (63–322) | 445 (183–888) | 1170 (520–2178) |