Table 1.
Baseline characteristics of the overall cohort and the early surgery and delayed surgery groups, before and after IPTW adjustment
| Overall | Before IPTW | After IPTW | |||||
|---|---|---|---|---|---|---|---|
| Early surgery group | Delayed surgery group | SMD | Early surgery group | Delayed surgery group | SMD | ||
| n (%) | 11,087 | 3,170 (28.6) | 7,917 (71.4) | - | 10,922.6 | 11,105.1 | - |
| Hospital Admission to Initial Operation (Days), mean (SD) | 3.75 (1.72) | 1.74 (0.44) | 4.55 (1.34) | - | - | - | - |
| Age, years, mean (SD) | 82.12 (8.09) | 81.69 (8.16) | 82.29 (8.06) | 0.073 | 82.29 (8.24) | 82.15 (8.09) | 0.018 |
| Female, n (%) | 9,736 (87.8) | 2,733 (86.2) | 7,003 (88.5) | 0.067 | 9,550.5 (87.4) | 9,740.6 (87.7) | 0.008 |
| BMI, kg/m2, mean (SD) | 22.26 (3.98) | 22.26 (3.84) | 22.26 (4.03) | < 0.001 | 22.24 (3.82) | 22.27 (4.03) | 0.008 |
| Barthel Index (BI) at admission, mean (SD) | 16.07 (27.7) | 17.95 (29.8) | 15.32 (26.8) | 0.093 | 16.1 (27.8) | 16.1 (27.5) | < 0.001 |
| Pre-admission living status: Facility, n (%) | 1,708 (15.4) | 434 (13.7) | 1,274 (16.1) | 0.067 | 1,644.5 (15.1) | 1,714.8 (15.4) | 0.011 |
| Holiday admission, n (%) | 3,422 (30.9) | 535 (16.9) | 2,887 (36.5) | 0.454 | 3,470.1 (31.8) | 3,421.8 (30.8) | 0.022 |
| Pre-holiday admission, n (%) | 1,870 (16.9) | 301 (9.5) | 1,569 (19.8) | 0.295 | 1,486.6 (13.6) | 1,851.58 (16.7) | 0.088 |
| Heart failure, n (%) | 757 (6.8) | 174 (5.5) | 583 (7.4) | 0.077 | 909.2 (8.3) | 766.7 (6.9) | 0.058 |
| Cardiovascular disease, n (%) | 825 (7.4) | 220 (6.9) | 605 (7.6) | 0.027 | 974.5 (8.9) | 837.0 (7.5) | 0.053 |
| COPD, n (%) | 97 (0.9) | 23 (0.7) | 74 (0.9) | 0.023 | 83.7 (0.8) | 94.2 (0.8) | 0.009 |
| Diabetes mellitus, n (%) | 1,944 (17.5) | 502 (15.8) | 1,442 (18.2) | 0.063 | 2,028.4 (18.6) | 1,970.4 (17.7) | 0.022 |
| Dementia, n (%) | 1,444 (13.0) | 364 (11.5) | 1,080 (13.6) | 0.065 | 1,440.7 (13.2) | 1,448.9 (13.0) | 0.004 |
| Chronic renal failure, n (%) | 51 (0.5) | 9 (0.3) | 42 (0.5) | 0.039 | 57.4 (0.5) | 52.2 (0.5) | 0.009 |
| Rheumatic disease, n (%) | 426 (3.8) | 107 (3.4) | 319 (4.0) | 0.035 | 447.8 (4.1) | 429.8 (3.9) | 0.012 |
| Cerebrovascular disease, n (%) | 854 (7.7) | 201 (6.3) | 653 (8.2) | 0.073 | 804.6 (7.4) | 856.3 (7.7) | 0.013 |
| Non-metastatic solid tumor, n (%) | 600 (5.4) | 168 (5.3) | 432 (5.5) | 0.007 | 636.5 (5.8) | 601.1 (5.4) | 0.018 |
| Metastatic solid tumor, n (%) | 194 (1.7) | 58 (1.8) | 136 (1.7) | 0.008 | 184.6 (1.7) | 192.3 (1.7) | 0.003 |
| Pneumonia at admission, n (%) | 52 (0.5) | 7 (0.2) | 45 (0.6) | 0.055 | 32.4 (0.3) | 51.2 (0.5) | 0.026 |
| Urinary tract infection at admission, n (%) | 60 (0.5) | 11 (0.3) | 49 (0.6) | 0.039 | 51.9 (0.5) | 60.1 (0.5) | 0.010 |
| Decubitus ulcer at admission, n (%) | 76 (0.7) | 10 (0.3) | 66 (0.8) | 0.069 | 43.4 (0.4) | 75.3 (0.7) | 0.037 |
| Traumatic brain injury, n (%) | 23 (0.2) | 8 (0.3) | 15 (0.2) | 0.013 | 20.1(0.2) | 24.1(0.2) | 0.007 |
| Chest injury, n (%) | 57 (0.5) | 18 (0.6) | 39 (0.5) | 0.010 | 81.4 (0.7) | 59.0 (0.5) | 0.030 |
| Abdominal injury, n (%) | 5 (0.0) | 2 (0.1) | 3 (0.0) | 0.011 | 5.7 (0.1) | 5.9 (0.1) | < 0.001 |
| Pelvic injury, n (%) | 37 (0.3) | 14 (0.4) | 23 (0.3) | 0.025 | 29.4 (0.3) | 38.2 (0.3) | 0.012 |
| Spinal injury, n (%) | 77 (0.7) | 22 (0.7) | 55 (0.7) | < 0.001 | 96.4 (0.9) | 78.6 (0.7) | 0.021 |
| Other open fractures, n (%) | 11 (0.1) | 5 (0.2) | 6 (0.1) | 0.024 | 8.39 (0.1) | 8.65 (0.1) | < 0.001 |
| Other fractures, n (%) | 651 (5.9) | 175 (5.5) | 476 (6.0) | 0.021 | 665.2 (6.1) | 652.3 (5.9) | 0.003 |
| Skeletal traction, n (%) | 5,013 (45.2) | 851 (26.8) | 4,162 (52.6) | 0.545 | 4,892.5 (44.8) | 5,006.1 (45.1) | 0.006 |
| Skin traction, n (%) | 1,211 (10.9) | 300 (9.5) | 911 (11.5) | 0.067 | 1,088.0 (10.0) | 1,203.8 (10.8) | 0.029 |
| General anesthesia, n (%) | 7,656 (69.1) | 1,983 (62.6) | 5,673 (71.7) | 0.195 | 7,691.1 (70.4) | 7,697.8 (69.3) | 0.023 |
| Preoperative blood transfusion, n (%) | 1,997 (18.0) | 206 (6.5) | 1,791 (22.6) | 0.470 | 1,952.2 (17.9) | 1,997.0 (18.0) | 0.003 |
| Antithrombotic drug, n (%) | 4,552 (41.1) | 1,215 (38.3) | 3,337 (42.1) | 0.078 | 4,545.8 (41.6) | 4,565.7 (41.1) | 0.010 |
| Oral steroids, n (%) | 654 (5.9) | 167 (5.3) | 487 (6.2) | 0.038 | 665.2 (6.1) | 658.4 (5.9) | 0.007 |
IPTW Inverse probability of treatment weighting, SMD Standard mean difference, SD Standard deviation, BMI body mass index, COPD chronic obstructive pulmonary disease
Barthel Index in “Before IPTW” is based on non-missing cases (n = 9,472, 85.4%). The “After IPTW” value for this variable is the pooled estimate derived from multiple imputation
n in “After IPTW” columns represents the effective sample size after weighting