| Parameters | Event-occurrence group (n = 6) | Event-free group (n = 13) | p Value |
| Age (years) | 64.0 ± 7.1 | 64.3 ± 6.1 | 0.923 |
| Sex (male/female) | 5/1 | 11/2 | 1.00 |
| Obstructive jaundice | 5 | 8 | 0.605 |
| Abdominal pain | 2 | 8 | 0.350 |
| Pancretic ductal change diffuse/focal | 3/3 | 7/6 | 1.00 |
| IgG4 (mg/dl) | 397 ± 230 (n = 4) | 607 ± 386 (n = 12) | 0.222 |
| Initial dose of PSL (mg) | 36 ± 9.1 | 32 ± 4.3 | 0.405 |
| Cessation of CST | 2 | 0 | 0.088 |
CST, Corticosteroid treatment; PSL, prednisolone.