Patient and procedural characteristics
| Total | 1–3 months | 4–6 months | 7–9 months | P value | |
| N | 128 | 43 | 47 | 38 | |
| Age (years) (mean±SD) | 69.6±14.5 | 69.6±11.9 | 68.7±16.1 | 70.7±15.2 | 0.818 |
| Sex | 0.248 | ||||
| Male | 49 (39.1%) | 17 (39.5%) | 14 (29.8%) | 18 (47.4%) | |
| Female | 79 (61.7%) | 26 (60.5%) | 33 (70.2%) | 20 (52.6%) | |
| Indications for ERCP (no, %) | 0.541 | ||||
| Bile duct stone | 78 (60.9%) | 27 (62.8%) | 30 (63.8%) | 21 (55.3%) | |
| Bile duct cancer | 17 (13.3%) | 6 (14.0%) | 3 (6.4%) | 8 (21.1%) | |
| Pancreatic cancer | 4 (3.1%) | 0 (0.0%) | 2 (4.3%) | 2 (5.3%) | |
| Pancreatitis | 4 (3.1%) | 2 (4.7%) | 1 (2.1%) | 1 (2.6%) | |
| Others | 25 (19.5%) | 8 (18.6%) | 11 (23.4%) | 6 (15.8%) | |
| Fluoroscopy time (s) (mean±SD) | 244.9±257.0 | 254.6±354.5 | 194.9±156.9 | 295.7±217.7 | 0.191 |
| Number of digital radiographs (mean±SD) | 3.7±1.0 | 3.8±1.2 | 3.3±0.8 | 4.2±0.9 | <0.001 |
ERCP, endoscopic retrograde cholangiopancreatography.