Table 1 Chronological changes in clinical, operative, pathological characteristics and postoperative progression before PSM
|  | Early period (1995 ~ 2012) (n = 466) | Late period (2013 ~ 2018) (n = 338) | p-value | |||
|---|---|---|---|---|---|---|
Clinical characteristics | Â | Â | Â | |||
 Age | 62.7 ± 9.3 | 66.7 ± 8.5 | < 0.001 | |||
 Sex |  |  | 0.881 | |||
  Male | 302 (64.8) | 221 (65.4) |  | |||
  Female | 164 (35.2) | 117 (34.6) |  | |||
 BMI (kg/m2) | 23.0 ± 3.0 | 23.4 ± 3.1 | 0.041 | |||
 DM |  |  | 0.004 | |||
  No | 390 (83.7) | 255 (75.4) |  | |||
  Yes | 76 (16.3) | 83 (24.6) |  | |||
 ASA score |  |  | < 0.001 | |||
  1 | 124 (26.6) | 42 (12.4) |  | |||
  2 | 293 (62.9) | 261 (77.2) |  | |||
  3 | 42 (9.0) | 35 (10.4) |  | |||
  4 | 1 (0.2) | 0 (0.0) |  | |||
  Unknown | 6 (1.3) | 0 (0.0) |  | |||
 Preoperative total bilirubin (mg/dL) | 9.8 ± 9.0 | 7.1 ± 7.6 | < 0.001 | |||
 Preoperative biliary drainage |  |  | 0.009 | |||
  No | 61 (13.1) | 68 (20.1) |  | |||
  Yes | 405 (86.9) | 270 (79.9) |  | |||
Preoperative CA19-9 |  |  | < 0.001 | |||
  ≤ 37 U/mL | 176 (37.8) | 177 (52.4) |  | |||
  \(>\) 37 U/mL | 280 (60.1) | 148 (43.8) |  | |||
  Unknown | 10 (2.1) | 13 (3.8) |  | |||
Operative characteristics | Â | Â | Â | |||
 Operation type |  |  | 0.003 | |||
  PPPD | 280 (60.1) | 243 (71.9) |  | |||
  PRPD | 152 (32.6) | 75 (22.2) |  | |||
  HPD | 27 (5.8) | 18 (5.3) |  | |||
  TP | 7 (1.5) | 2 (0.6) |  | |||
 Vascular resection |  |  | 0.172 | |||
  No | 449 (96.4) | 318 (94.1) |  | |||
  Yes | 17 (3.6) | 20 (5.9) |  | |||
 Combined operation |  |  | 0.828 | |||
  No | 454 (97.4) | 328 (97.0) |  | |||
  Yes | 12 (2.6) | 10 (3.0) |  | |||
 Operation duration (minutes) | 339.7 ± 67.5 | 320.8 ± 64.8 | < 0.001 | |||
 EBL (mL) | 670.9 ± 637.6 | 388.9 ± 268.8 | < 0.001 | |||
 Intraoperative transfusion |  |  | < 0.001 | |||
  No | 350 (75.1) | 315 (93.2) |  | |||
  Yes | 116 (24.9) | 23 (6.8) |  | |||
Pathological characteristics | Â | Â | Â | |||
 Tumor size | 2.9 ± 1.4 | 2.8 ± 1.3 | 0.343 | |||
 T stage (AJCC 7th) |  |  | 0.002 | |||
| Â | Â | Tis | 1 (0.2) | Tis | 1 (0.3) | Â |
| Â | Â | T1 | 36 (7.7) | T1 | 52 (15.4) | Â |
| Â | Â | T2 | 125 (26.8) | T2 | 72 (21.3) | Â |
| Â | Â | T3 | 301 (64.6) | T3 | 213 (63.0) | Â |
| Â | Â | T4 | 3 (0.6) | T4 | 0 (0.0) | Â |
 Differentiation |  |  | < 0.001 | |||
  Well | 72 (15.5) | 34 (10.1) |  | |||
  Moderately | 248 (53.2) | 203 (60.1) |  | |||
  Poorly | 115 (24.7) | 92 (27.2) |  | |||
  Undifferentiated | 4 (0.9) | 6 (1.8) |  | |||
  Unknown | 27 (5.8) | 3 (0.9) |  | |||
 N stage (AJCC 8th) |  |  | 0.965 | |||
  N0 | 307 (65.9) | 226 (66.9) |  | |||
  N1 | 124 (26.6) | 87 (25.7) |  | |||
  N2 | 35 (7.5) | 25 (7.4) |  | |||
 Harvested LN | 21.7 ± 11.7 | 19.1 ± 8.8 | 0.001 | |||
 Metastatic LN | 1.0 ± 2.1 | 0.9 ± 2.1 | 0.611 | |||
 M stage |  |  | - | |||
  M0 | 466 (100.0) | 338 (100.0) |  | |||
  M1 | 0 (0.0) | 0 (0.0) |  | |||
 Resection margin |  |  | 0.406 | |||
  R0 | 434 (93.1) | 307 (90.8) |  | |||
  R1 | 30 (6.4) | 28 (8.3) |  | |||
  R2 | 2 (0.4) | 3 (0.9) |  | |||
 PNI |  |  | < 0.001 | |||
  No | 50 (10.7) | 72 (21.3) |  | |||
  Yes | 264 (56.7) | 263 (77.8) |  | |||
  Unknown | 152 (32.6) | 3 (0.9) |  | |||
 LVI |  |  | < 0.001 | |||
  No | 38 (8.2) | 192 (56.8) |  | |||
  Yes | 66 (14.2) | 143 (42.3) |  | |||
  Unknown | 362 (77.7) | 3 (0.9) |  | |||
Postoperative progression | Â | Â | Â | |||
 Postoperative hospitalization (days) | 20.4 ± 14.7 | 14.3 ± 9.8 | < 0.001 | |||
 POPF |  |  | 0.626 | |||
  No (biochemical leak) | 410 (88.0) | 300 (88.8) |  | |||
  Grade B | 46 (9.9) | 34 (10.1) |  | |||
  Grade C | 10 (2.1) | 4 (1.2) |  | |||
 Clavien-Dindo classification |  |  | < 0.001 | |||
  No complication | 250 (53.6) | 177 (52.4) |  | |||
  I | 46 (9.9) | 2 (0.6) |  | |||
  II | 65 (13.9) | 67 (19.8) |  | |||
  IIIa | 71 (15.2) | 65 (19.2) |  | |||
  IIIb | 16 (3.4) | 8 (2.4) |  | |||
  IVa | 11 (2.4) | 14 (4.1) |  | |||
  IVb | 0 (0.0) | 2 (0.6) |  | |||
  V | 7 (1.5) | 3 (0.9) |  | |||
 In-hospital mortality (%) | 6 (1.3) | 2 (0.6) | 0.326 | |||
 30-day mortality (%) | 6 (1.3) | 3 (0.9) | 0.595 | |||
 90-day mortality (%) | 11 (2.4) | 6 (1.8) | 0.569 | |||
 Adjuvant treatment |  |  | < 0.001 | |||
  No | 392 (84.1) | 228 (67.5) |  | |||
  Yes | 74 (15.9) | 110 (32.5) |  | |||