Table 1 Pre-Operative Characteristics of the Patients According to Subgroups
|  | All Patients | Brain | Spine | p value | All patients | PPC | No PPC | p value | All patients | ARISCAT < 26 | ARISCAT ≥ 26 | p value |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
n (%) | 784 (100) | 376 (48) | 408 (52) | Â | 777 (100.0) | 81 (10.4) | 696 (89.6) | Â | 548 (73.3) | 200 (26.7) | 748 (100.0) | Â |
Demographics | ||||||||||||
Age, years, mean (SD) | 53 (16) | 52 (16) | 54 (15) | 0.104 | 53 (16) | 59 (15) | 52 (16) | 0.000 | 50 (15) | 51 (15) | 63 (16) | 0.000 |
Gender, n (%) | Â | Â | ||||||||||
 Male | 392 (50) | 183 (48.7) | 209 (51.2) | 0.060 | 392 (50.5) | 37 (45.7) | 355 (51.0) | 0.072 | 285 (52.0) | 97 (48.5) | 382 (51.1) | 0.065 |
Ethnicity, n (%) | Â | Â | ||||||||||
 Black | 2 (0.3) | 0 (0.0) | 2 (0.5) |  | 2 (0.3) | 2 (2.5) | 0 (0.0) |  | 1 (0.2) | 1 (0.5) | 2 (0.3) | 0.663 |
 Caucasian | 709 (90.4) | 340 (90.4) | 369 (90.4) |  | 704 (90.6) | 71 (87.7) | 633 (90.9) |  | 493 (90.0) | 183 (91.5) | 676 (90.4) |  |
 Asian | 4 (0.5) | 1 (0.3) | 3 (0.7) |  | 4 (0.5) | 1 (1.2) | 3 (0.4) |  | 4 (0.7) | 0 (0.0) | 4 (0.5) |  |
 Other | 33 (4.2) | 13 (3.5) | 20 (4.9) |  | 33 (4.2) | 2 (2.5) | 31 (4.5) |  | 26 (4.7) | 6 (3.0) | 32 (4.3) |  |
Anthropometry | ||||||||||||
Height, cm, mean (SD) | 170 (10) | 170 (10) | 170 (9) | 0.416 | 170 (10) | 169 (10) | 170 (10) | 0.421 | 170 (10) | 169 (10) | 170 (10) | 0.243 |
Weight, kg, mean (SD) | 79 (17) | 80 (18) | 78 (16) | 0.309 | 79 (17) | 80 (18) | 79 (17) | 0.597 | 79 (17) | 79 (17) | 79 (17) | 0.677 |
BMI, kg/m2, mean (SD) | 27.3 (5.8) | 27.7 (6.6) | 27.0 (4.9) | 0.148 | 27.3 (5.8) | 28.3 (6.5) | 27.2 (5.7) | 0.141 | 27.3 (6.0) | 27.4 (5.0) | 27.3 (5.8) | 0.874 |
Co-morbidities, n (%) | Â | Â | ||||||||||
 Co-morbidities | 161 (20.5) | 84 (22.3) | 77 (18.9) | 0.230 | 160 (20.6) | 30 (37.0) | 130 (18.7) | 0.000 | 98 (17.9) | 59 (29.5) | 157 (21.0) | 0.001 |
 COPD | 47 (6.0) | 21 (5.6) | 26 (6.4) | 0.643 | 47 (6.0) | 8 (9.9) | 39 (5.6) | 0.127 | 32 (5.8) | 15 (7.5) | 47 (6.3) | 0.407 |
 Respiratory | 19 (2.4) | 8 (2.1) | 11 (2.7) | 0.605 | 19 (2.4) | 5 (6.2) | 14 (2.0) | 0.022 | 12 (2.2) | 7 (3.5) | 19 (2.5) | 0.313 |
 Liver cirrhosis | 4 (0.5) | 2 (0.5) | 2 (0.5) | 0.935 | 4 (0.5) | 0 (0.0) | 4 (0.6) | 0.494 | 3 (0.5) | 1 (0.5) | 4 (0.5) | 0.937 |
 Chronic kidney failure | 16 (2.0) | 4 (1.1) | 12 (2.9) | 0.063 | 16 (2.1) | 4 (4.9) | 12 (1.7) | 0.054 | 6 (1.1) | 9 (4.5) | 15 (2.0) | 0.003 |
 Heart failure | 45 (5.7) | 27 (7.2) | 18 (4.4) | 0.096 | 45 (5.8) | 10 (12.3) | 35 (5.0) | 0.008 | 29 (5.3) | 14 (7.0) | 43 (5.7) | 0.374 |
 Neuro disease | 12 (1.5) | 8 (2.1) | 4 (1.0) | 0.191 | 12 (1.5) | 2 (2.5) | 10 (1.4) | 0.476 | 11 (2.0) | 1 (0.5) | 12 (1.6) | 0.146 |
Pre-operative medical history | ||||||||||||
ASA physical status, n (%) | 214 (27.4) | 96 (25.5) | 118 (29.1) | 0.007 | 208 (26.8) | 14 (17.5) | 194 (27.9) | 0.000 | 165 (30.1) | 29 (14.6) | 194 (26.0) | 0.000 |
 ASA I | 395 (50.5) | 178 (47.3) | 217 (53.4) |  | 395 (51.0) | 33 (41.3) | 362 (52.1) |  | 292 (53.3) | 90 (45.2) | 382 (51.1) |  |
 ASA II | 395 (50.5) | 178 (47.3) | 217 (53.4) |  | 153 (19.7) | 28 (35.0) | 125 (18.0) |  | 85 (15.5) | 68 (34.2) | 153 (20.5) |  |
 ASA III | 154 (19.7) | 87 (23.1) | 67 (16.5) |  | 18 (2.3) | 5 (6.3) | 13 (1.9) |  | 6 (1.1) | 11 (5.5) | 17 (2.3) |  |
 ASA IV | 18 (2.3) | 14 (3.7) | 4 (1.0) |  | 1 (0.1) | 0 (0.0) | 1 (0.1) |  | 0 (0.0) | 1 (0.5) | 1 (0.1) |  |
 ASA V | 1 (0.1) | 1 (0.3) | 0 (0.0) |  | 208 (26.8) | 14 (17.5) | 194 (27.9) |  | 165 (30.1) | 29 (14.6) | 194 (26.0) |  |
Functional status, n (%) | 0.004 | Â | 0.000 | Â | 0.006 | |||||||
 Independent | 708 (90.3) | 327 (87.0) | 381 (93.4) |  | 702 (90.3) | 67 (82.7) | 635 (91.2) |  | 506 (92.3) | 168 (84.0) | 674 (90.1) |  |
 Partially dependent | 62 (7.9) | 38 (10.1) | 24 (5.9) |  | 62 (8.0) | 12 (14.8) | 50 (7.2) |  | 33 (6.0) | 27 (13.5) | 60 (8.0) |  |
 Totally dependent | 13 (1.7) | 11 (2.9) | 2 (0.5) |  | 12 (1.5) | 2 (2.5) | 10 (1.4) |  | 8 (1.5) | 5 (2.5) | 13 (1.7) |  |
ARISCAT score, median (IQR) | 215 (27.4) | 102 (27.1) | 113 (27.7) | 0.000 | 16 (3; 26) | 23 (11; 32) | 16 (3; 24) | 0.002 | 8 (3; 18) | 31 (26; 37) | 16 (3; 26) | 0.000 |
Smoking, n (%) | 40 (5.1) | 23 (6.1) | 17 (4.2) | 0.859 | 214 (27.5) | 22 (27.2) | 192 (27.6) | 0.442 | 165 (30.1) | 44 (22.0) | 209 (27.9) | 0.029 |
Transfusion (< 24 h), n (%) | 5 (0.6) | 3 (0.8) | 2 (0.5) | 0.215 | 39 (5.0) | 6 (7.4) | 33 (4.7) | 0.000 | 16 (2.9) | 22 (11.0) | 38 (5.1) | 0.000 |
 RBC transfusion (< 24 h) | 28 (3.6) | 16 (4.3) | 12 (2.9) | 0.589 | 5 (0.6) | 1 (1.2) | 4 (0.6) | 0.722 | 1 (0.2) | 4 (2.0) | 5 (0.7) | 0.007 |
Respiratory infection (<30d), n (%) | 1 (0.1) | 0 (0.0) | 1 (0.2) | 0.322 | 28 (3.6) | 3 (3.7) | 25 (3.6) | 0.002 | 7 (1.3) | 19 (9.5) | 26 (3.5) | 0.000 |
Laboratory tests and vital signs | ||||||||||||
Pre-operative values | ||||||||||||
 SpO2, %, median (IQR) | 97 (96; 99) | 97 (96; 98) | 97 (96; 99) | 0.230 | 97 (96; 99) | 97 (95; 98) | 98 (96; 99) | 0.002 | 98 (96; 99) | 96 (94; 98) | 97 (96; 99) | 0.000 |
 Hb, (g/dL), mean (SD) | 13.8 (1.8) | 13.8 (1.8) | 13.9 (1.8) | 0.540 | 13.8 (1.8) | 13.7 (2.0) | 13.8 (1.8) | 0.442 | 14.0 (1.6) | 13.3 (2.1) | 13.8 (1.8) | 0.000 |
 WBC, (cell/mm3), mean (SD) | 7879 (3497) | 8199 (3097) | 7568 (3825) | 0.019 | 7891 (3503) | 9261 (6168) | 7721 (2978) | 0.000 | 7696 (3362) | 8438 (3845) | 7905 (3518) | 0.015 |
 Creatinine, (mg/dL), mean (SD) | 0.89 (0.69) | 0.90 (0.86) | 0.88 (0.49) | 0.758 | 0.89 (0.69) | 0.87 (0.28) | 0.90 (0.73) | 0.722 | 0.87 (0.59) | 0.95 (0.91) | 0.89 (0.70) | 0.192 |
Surgical characteristics | ||||||||||||
Condition, n (%) | 0.318 | Â | 0.140 | Â | 0.000 | |||||||
 Elective | 717 (91.5) | 338 (89.9) | 379 (92.9) |  | 712 (91.6) | 73 (90.1) | 639 (91.8) |  | 513 (93.6) | 172 (86.0) | 685 (91.6) |  |
 Urgency | 50 (6.4) | 28 (7.4) | 22 (5.4) |  | 49 (6.3) | 4 (4.9) | 45 (6.5) |  | 31 (5.7) | 16 (8.0) | 47 (6.3) |  |
 Emergency | 17 (2.2) | 10 (2.7) | 7 (1.7) |  | 16 (2.1) | 4 (4.9) | 12 (1.7) |  | 4 (0.7) | 12 (6.0) | 16 (2.1) |  |
Planned duration, hours, n (%) | 0.000 | Â | 0.000 | Â | 0.000 | |||||||
 0 | 1 (0.1) | 1 (0.3) | 0 (0.0) |  | 1 (0.1) | 0 (0.0) | 1 (0.1) |  |  |  |  |  |
 ≤ 2 | 432 (55.1) | 186 (49.5) | 246 (60.3) |  | 426 (54.8) | 36 (44.4) | 390 (56.0) |  | 378 (69.0) | 25 (12.5) | 403 (53.9) |  |
 2–3 | 201 (25.6) | 90 (23.9) | 111 (27.2) |  | 201 (25.9) | 15 (18.5) | 186 (26.7) |  | 124 (22.6) | 73 (36.5) | 197 (26.3) |  |
 > 3 | 150 (19.1) | 99 (26.3) | 51 (12.5) |  | 149 (19.2) | 30 (37.0) | 119 (17.1) |  | 46 (8.4) | 102 (51.0) | 148 (19.8) |  |
Antibiotic prophylaxis, n (%) | 711 (90.9) | 338 (90.1) | 373 (91.6) | 0.462 | 705 (91.0) | 74 (91.4) | 631 (90.9) | 0.897 | 500 (91.4) | 184 (92.0) | 684 (91.6) | 0.796 |