Table 1 Clinical characteristics of the subjects in the training set
Characteristics | All cases(n = 3,525) | Normal LOS group(n = 2,693) | Prolonged LOS group(n = 832) | p-value |
|---|---|---|---|---|
Age (mean [SD]) | 57.66 (12.33) | 57.15 (11.83) | 59.32 (13.69) | < 0.001 |
Number of preoperative diagnoses (median [IQR]) | 4.00 [3.00, 7.00] | 4.00 [3.00, 6.00] | 6.00 [4.00, 8.00] | < 0.001 |
Number of hospitalizations (median [IQR]) | 1.00 [1.00, 1.00] | 1.00 [1.00, 1.00] | 1.00 [1.00, 2.00] | < 0.001 |
Operative time (mean (SD)) | 2.24 (1.12) | 2.09 (0.99) | 2.73 (1.34) | < 0.001 |
Gender/male (%) | 1628 (46.2) | 1246 (46.3) | 382 (45.9) | 0.889 |
BMI (%) |  |  |  | < 0.001 |
 <18.5 | 67 (1.9) | 50 (1.9) | 17 (2.0) |  |
 18.5 ~ 23.9 | 1691 (48.0) | 1384 (51.4) | 307 (36.9) |  |
 ≥ 24 | 1767 (50.1) | 1259 (46.7) | 508 (61.1) |  |
Ethnic group (%) |  |  |  | 0.743 |
 Han | 2240 (63.6) | 1707 (63.4) | 533 (64.2) |  |
 Zhuang | 1055 (29.9) | 810 (30.1) | 245 (29.4) |  |
 Dong | 67 (1.9) | 50 (1.9) | 17 (2.0) |  |
 Miao | 50 (1.4) | 38 (1.4) | 12 (1.4) |  |
 Yao | 47 (1.3) | 40 (1.5) | 7 (0.8) |  |
 Other | 66 (1.9) | 48 (1.7) | 18 (2.2) |  |
Marital status (%) | Â | Â | Â | 0.001 |
 Unmarried | 52 (1.5) | 32 (1.2) | 20 (2.4) |  |
 Married | 2630 (74.7) | 2022 (75.1) | 608 (73.1) |  |
 Widowed | 1 (0.0) | 0 (0.0) | 1 (0.1) |  |
 Divorced | 5 (0.1) | 1 (0.0) | 4 (0.5) |  |
 Other | 837 (23.7) | 638 (23.7) | 199 (23.9) |  |
Occupation (%) |  |  |  | < 0.001 |
 Worker | 155 (4.4) | 107 (4.0) | 48 (5.8) |  |
 Retiree | 1404 (39.8) | 1104 (41.0) | 300 (36.0) |  |
 Business Services | 602 (17.1) | 430 (16.0) | 172 (20.7) |  |
 Household and non-working | 585 (16.6) | 467 (17.3) | 118 (14.2) |  |
 Farmer | 310 (8.8) | 216 (8.0) | 94 (11.3) |  |
 Other | 469 (13.3) | 369 (13.7) | 100 (12.0) |  |
Education (%) |  |  |  | < 0.001 |
 Primary school and below | 812 (23.1) | 556 (20.6) | 256 (30.8) |  |
 Junior to Senior | 702 (19.9) | 543 (20.2) | 159 (19.1) |  |
 College and above | 75 (2.1) | 59 (2.2) | 16 (1.9) |  |
 Other | 1936 (54.9) | 1535 (57.0) | 401 (48.2) |  |
History of surgery (%) | 989 (28.1) | 700 (26.0) | 289 (34.7) | < 0.001 |
Critical patients (%) | 104 (3.0) | 44 (1.6) | 60 (7.2) | < 0.001 |
Case stage(C + D) (%) | 667 (18.9) | 492 (18.3) | 175 (21.0) | 0.177 |
Surgeon’s professional title (chief physician) (%) | 2541 (72.1) | 1923 (71.4) | 618 (74.3) | 0.116 |
Blood transfusion (%) | 258 (7.3) | 82 (3.0) | 176 (21.2) | < 0.001 |
Admission route (%) |  |  |  | < 0.001 |
 Emergency | 190 (5.4) | 98 (3.6) | 92 (11.1) |  |
   Outpatient | 3325 (94.3) | 2590 (96.2) | 735 (88.3) |  |
 Other | 10 (0.3) | 5 (0.2) | 5 (0.6) |  |
Surgical type/elective surgery (%) | 3335 (94.6) | 2595 (96.4) | 740 (88.9) | < 0.001 |
Blood Type (%) | Â | Â | Â | 0.231 |
 A | 1505 (42.7) | 1175 (43.6) | 330 (39.7) |  |
 B | 855 (24.3) | 647 (24.0) | 208 (25.0) |  |
 AB | 932 (26.4) | 691 (25.7) | 241 (29.0) |  |
 O | 211 (6.0) | 162 (6.0) | 49 (5.9) |  |
 Other | 22 (0.6) | 18 (0.7) | 4 (0.4) |  |
Use of TXA (%) | 2404 (68.2) | 1915 (71.1) | 489 (58.8) | < 0.001 |
ASA ≥ 3 (%) | 583 (16.5) | 390 (14.5) | 193 (23.2) | < 0.001 |
Diabetes (%) | 336 (9.5) | 207 (7.7) | 129 (15.5) | < 0.001 |
Sleep apnea syndrome (%) | 1 (0.0) | 1 (0.0) | 0 (0.0) | 1.000 |
COPD (%) | 6 (0.2) | 5 (0.2) | 1 (0.1) | 1.000 |
Cardiac arrhythmias (%) | 174 (4.9) | 129 (4.8) | 45 (5.4) | 0.530 |
Heart failure (%) | 125 (3.5) | 79 (2.9) | 46 (5.5) | < 0.001 |
Coronary artery disease (%) | 93 (2.6) | 62 (2.3) | 31 (3.7) | 0.034 |
ESKD/CKD (%) | 74 (2.1) | 34 (1.3) | 40 (4.8) | < 0.001 |
Anxiety or Depression (%) | 17 (0.5) | 7 (0.3) | 10 (1.2) | 0.002 |
Hypertension (%) | 882 (25.0) | 627 (23.3) | 255 (30.6) | < 0.001 |
Peripheral vascular disease (%) | 382 (10.8) | 266 (9.9) | 116 (13.9) | 0.001 |
Anemia (%) | 209 (5.9) | 101 (3.8) | 108 (13.0) | < 0.001 |
Coagulation defects or purpura or hemorrhagic disorders (%) | 18 (0.5) | 11 (0.4) | 7 (0.8) | 0.210 |
Malignant neoplasm (%) | 80 (2.3) | 45 (1.7) | 35 (4.2) | < 0.001 |
Electrolyte disturbance (%) | 104 (3.0) | 43 (1.6) | 61 (7.3) | < 0.001 |
Osteoporosis (%) | 885 (25.1) | 676 (25.1) | 209 (25.1) | 1.000 |
Surgical procedure performed (%) |  |  |  | < 0.001 |
 Spinal fusion not otherwise specified | 51 (1.4) | 23 (0.8) | 28 (3.4) |  |
 Atlanto-axial spinal fusion | 11 (0.3) | 5 (0.2) | 6 (0.7) |  |
 Other cervical fusion of the anterior column, anterior method | 575 (16.3) | 427 (15.8) | 148 (17.8) |  |
 Other cervical fusion in the posterior column, posterior method | 72 (2.0) | 36 (1.3) | 36 (4.3) |  |
 Dorsal and dorsal lumbar fusion of the anterior column, anterior method | 23 (0.7) | 4 (0.1) | 19 (2.3) |  |
 Dorsal and dorsolumbar fusion, posterior method | 107 (3.0) | 58 (2.2) | 49 (5.9) |  |
 Lumbar and lumbosacral fusion in the anterior column, anterior meth | 606 (17.2) | 462 (17.2) | 144 (17.3) |  |
 Lumbar and lumbosacral fusion of the posterior column, posterior method | 1958 (55.6) | 1577 (58.6) | 381 (45.8) |  |
 Lumbar and lumbosacral fusion in the anterior column, posterior method | 122 (3.5) | 101 (3.8) | 21 (2.5) |  |
4–8 segmental fusion (%) | 165 (4.7) | 100 (3.7) | 65 (7.8) | < 0.001 |
Weekday of surgery (%) |  |  |  | < 0.001 |
 Monday | 553 (15.7) | 391 (14.5) | 162 (19.5) |  |
 Tuesday | 676 (19.2) | 507 (18.8) | 169 (20.3) |  |
 Wednesday | 701 (19.9) | 543 (20.2) | 158 (19.0) |  |
 Thursday | 782 (22.2) | 610 (22.7) | 172 (20.7) |  |
 Friday | 695 (19.7) | 563 (20.9) | 132 (15.9) |  |
 Saturday | 60 (1.7) | 43 (1.6) | 17 (2.0) |  |
 Sunday | 58 (1.6) | 36 (1.3) | 22 (2.6) |  |
Quarter of surgery (%) |  |  |  | 0.574 |
 First | 973 (27.6) | 759 (28.2) | 214 (25.7) |  |
 Second | 842 (23.9) | 637 (23.6) | 205 (24.7) |  |
 Third | 940 (26.7) | 711 (26.4) | 229 (27.5) |  |
 Fourth | 770 (21.8) | 586 (21.8) | 184 (22.1) |  |