Table 1.
Population characteristics and data completeness
| Variable | Total study population (n=2756) | Missing data (%) |
|---|---|---|
| Age (years)* | 70 (62-77) | 0 |
| Sex | ||
| Male | 1441 (52) | 0 |
| Female | 1315 (48) | |
| Body mass index* | 24.8 (22.4-27.8) | 23 |
| ASA score | ||
| I | 637 (23) | 1 |
| II | 1639 (60) | |
| III | 428 (16) | |
| IV | 20 (1) | |
| Tobacco use | ||
| Active smoker | 441 (20) | 18 |
| Previous smoker | 950 (42) | |
| Non-smoker | 854 (38) | |
| Alcohol consumption (units/week) | ||
| 0 | 621 (28) | 19 |
| 1-14 | 1152 (52) | |
| 15-21 | 183 (8) | |
| >21 | 271 (12) | |
| Ischaemic heart disease | ||
| Yes | 341 (26) | 52 |
| No | 974 (74) | |
| Hypertension | ||
| Yes | 834 (64) | 52 |
| No | 478 (36) | |
| Lung disease | ||
| Yes | 196 (15) | 54 |
| No | 1084 (85) | |
| Diabetes mellitus | ||
| Yes | 259 (20) | 52 |
| No | 1060 (80) | |
| Tumour T stage | ||
| 1 | 161 (6) | 1 |
| 2 | 330 (12) | |
| 3 | 1720 (63) | |
| 4 | 516 (19) | |
| Procedure | ||
| Open | 1760 (64) | 0 |
| Laparoscopic | 996 (36) | |
| Resection | ||
| Colonic | 1988 (72) | 0 |
| Rectal | 768 (28) | |
| Intraoperative blood loss (mL)* | 210 (100-500) | 0 |
| Intraoperative transfusion | ||
| Yes | 573 (21) | 0 |
| No | 2178 (79) | |
| Anastomotic leakage | 179 (6) | 0 |
| Death within 30 days of surgery | 91 (3) | 0 |
Data are number (%) of patients unless stated otherwise. Totals of patients in each category do not add necessarily add up to 2756, owing to missing data. ASA=American Society of Anesthesiologists.
*Median (interquartile range).