Table 1.
Demographics, clinical, and laboratory variables between study groups before and after propensity-score matching.
| Variables | Pre-Matching Cohort n = 1682 |
Post-Matching Cohort (1:4) n = 495 |
||||
|---|---|---|---|---|---|---|
| VAP n = 99 |
Non-VAP n = 1583 |
p-Value | VAP n = 99 |
Non-VAP n = 396 |
p-Value | |
| Demographics | ||||||
| Age, mean (SD) (years) | 67.1 (15.1) | 66.9 (15.8) | 0.893 | 67.1 (15.1) | 66.9 (16.3) | 0.909 |
| Age ≥ 65 years, n (%) | 62 (60.6) | 968 (61.2) | 0.914 | 60 (60.6) | 248 (62.6) | 0.711 |
| Male, n (%) | 73 (73.7) | 911 (57.6) | 0.002 | 73 (73.7) | 292 (73.7) | 1.000 |
| Smoking, n (%) | 27 (27.3) | 397 (25.1) | 0.626 | 27 (27.3) | 121 (30.6) | 0.523 |
| BMI, mean (SD) (kg/m2) | 24.1 ± 5.6 | 24.0 ± 6.0 | 0.953 | 24.1 ± 5.6 | 24.0 ± 5.1 | 0.600 |
| Patient referred from ER, n (%) | 19 (19.2) | 389 (24.6) | 0.226 | 19 (19.2) | 102 (25.8) | 0.174 |
| Pre-ICU stay, mean (SD) (days) | 6.2 (8.6) | 7.0 (15.7) | 0.356 | 6.2 (8.6) | 6.8 (16.2) | 0.568 |
| SOFA score, mean (SD) * | 6.8 (3.5) | 6.0 (3.7) | 0.026 | 6.8 (3.5) | 6.0 (3.6) | 0.039 |
| Comorbidities | ||||||
| Charlson score, mean (SD) | 2.0 (2.1) | 2.1 (2.0) | 0.545 | 2.0 (2.1) | 2.0 (2.0) | 0.892 |
| Charlson score ≥ 3, n (%) | 34 (34.3) | 586 (37.0) | 0.593 | 34 (34.3) | 136 (34.3) | 1.000 |
| Myocardial infarction, n (%) | 3 (3.0) | 66 (4.2) | 0.786 | 3 (3.0) | 15 (3.8) | 0.734 |
| Congestive heart failure, n (%) | 5 (5.1) | 171 (10.8) | 0.07 | 5 (5.1) | 25 (6.3) | 0.638 |
| Cerebrovascular disease, n (%) | 11 (11.1) | 253 (16.0) | 0.197 | 11 (11.1) | 67 (16.9) | 0.156 |
| Chronic pulmonary disease, n (%) | 23 (23.2) | 248 (15.7) | 0.047 | 23 (23.2) | 66 (16.7) | 0.128 |
| Diabetes Mellitus, n (%) | 21 (21.2) | 407 (25.7) | 0.319 | 21 (21.2) | 96 (24.2) | 0.526 |
| Liver disease, n (%) | 20 (20.2) | 313 (19.8) | 0.917 | 20 (20.2) | 74 (18.7) | 0.731 |
| Cancer, n (%) | 34 (34.3) | 569 (35.9) | 0.747 | 34 (34.3) | 133 (33.6) | 0.887 |
| Interventions | ||||||
| MV > 7 days, n (%) | 61 (61.6) | 438 (27.7) | <0.001 | 61 (61.6) | 112 (28.3) | <0.001 |
| Tracheostomy, n (%) | 6 (6.1) | 75 (4.7) | 0.341 | 6 (6.1) | 23 (5.8) | 0.924 |
| Repeat intubation < 14 days, n (%) | 28 (28.3) | 247 (15.6) | <0.001 | 28 (28.3) | 68 (17.2) | 0.012 |
| Hemodialysis, n (%) | 15 (15.2) | 257 (16.2) | 0.776 | 15 (15.2) | 64 (16.2) | 0.806 |
| ECMO, n (%) | 4 (4.0) | 20 (1.3) | 0.048 | 4 (4.0) | 7 (1.8) | 0.242 |
| Central venous catheter, n (%) | 77 (77.8) | 1324 (83.6) | 0.129 | 77 (77.8) | 330 (83.3) | 0.196 |
| Total parenteral nutrition, n (%) | 43 (43.4) | 501 (31.7) | 0.015 | 43 (43.4) | 120 (30.3) | 0.013 |
| Double lumen, n (%) | 9 (9.1) | 150 (9.5) | 0.899 | 9 (9.1) | 37 (9.3) | 0.938 |
| Urinary catheter, n (%) | 93 (93.9) | 1512 (95.5) | 0.467 | 93 (93.9) | 377 (95.2) | 0.608 |
| Drainage catheter, n (%) | 87 (87.9) | 1385 (87.5) | 0.910 | 87 (87.9) | 337 (85.1) | 0.481 |
| Blood transfusion, n (%) | 87 (87.9) | 1426 (90.1) | 0.479 | 87 (87.9) | 360 (90.9) | 0.362 |
| ICU readmission, n (%) | 20 (20.2) | 280 (17.7) | 0.526 | 20 (20.2) | 65 (16.4) | 0.371 |
| Pre-exposed Rx | ||||||
| Antibiotics a (≥2 days) | 68 (68.7) | 973 (61.5) | 0.151 | 68 (68.7) | 256 (64.7) | 0.450 |
| Carbapenem a, n (%) | 38 (38.4) | 634 (40.1) | 0.743 | 38 (38.4) | 170 (42.9) | 0.413 |
| APP or APC a, n (%) | 36 (36.4) | 568 (35.9) | 0.923 | 36 (36.4) | 145 (36.6) | 0.963 |
| Fluoroquinolone a, n (%) | 17 (17.2) | 264 (16.7) | 0.898 | 17 (17.2) | 78 (19.7) | 0.568 |
| Chemotherapy b, n (%) | 7 (7.1) | 94 (5.9) | 0.645 | 7 (7.1) | 21 (5.3) | 0.496 |
| IMS b or Steroid b,c, n (%) | 17 (17.2) | 151 (9.5) | 0.014 | 17 (17.2) | 4 (10.6) | 0.071 |
| Surgical details | ||||||
| Critical condition, n (%) ** | 59 (59.6) | 744 (47.0) | 0.015 | 59 (59.6) | 183 (46.2) | 0.017 |
| Wound class ≥ 3, n(%) | 60 (60.6) | 929 (58.7) | 0.707 | 60 (60.6) | 227 (57.3) | 0.554 |
| ASA ≥ 3, n (%) | 91 (91.9) | 1370 (86.5) | 0.127 | 91 (91.9) | 345 (87.1) | 0.188 |
| ASA ≥ 4, n (%) | 28 (28.3) | 375 (23.7) | 0.299 | 28 (28.3) | 102 (25.8) | 0.610 |
| Op duration, mean (SD) minutes | 281.6(171.7) | 281.9 (192.1) | 0.987 | 281.6 (171.7) | 272.7(177.0) | 0.653 |
| Repeat Op before VAP, n (%) | 36 (36.4) | 535 (33.8) | 0.601 | 36 (36.4) | 153 (38.6) | 0.677 |
| Surgical site | ||||||
| -Gastrointestinal surgery, n (%) | 77 (77.8) | 1097 (69.3) | 0.075 | 77 (77.8) | 267 (67.4) | 0.045 |
| -Gastrointestinal tract, n (%) | 68 (68.7) | 956 (60.4) | 0.101 | 68 (68.7) | 234 (59.1) | 0.080 |
| -HPB, n (%) | 22 (22.2) | 257 (16.2) | 0.120 | 22 (22.2) | 57 (14.4) | 0.057 |
| -Abdominal wall, n (%) | 15 (15.2) | 251 (15.9) | 0.852 | 15 (15.2) | 60 (15.2) | 1.000 |
| -Urology (including kidney), n (%) | 8 (8.1) | 227 (14.3) | 0.081 | 8 (8.1) | 53 (13.4) | 0.151 |
| -Chest, n (%) | 3 (3.0) | 83 (5.2) | 0.332 | 3 (3.0) | 19 (4.8) | 0.591 |
| -Limbs, n (%) | 13 (13.1) | 246 (15.5) | 0.519 | 13 (13.1) | 66 (16.7) | 0.390 |
| -Others, n (%) | 1 (1.0) | 9 (0.6) | 0.458 | 1 (1.0) | 3 (0.8) | 1.000 |
| Lab data | ||||||
| PaO2/FiO2 mmHg, mean (SD) * | 280.3(116.6) | 338.5 (130.6) | <0.001 | 280.3 (116.6) | 348.6 (153.6) | <0.001 |
| Albumin < 3.5 mg/dL, n (%) * | 64 (64.7) | 958 (60.5) | 0.414 | 64 (64.7) | 244 (61.6) | 0.578 |
| ALT > 80 U/L, n (%) * | 12 (12.1) | 149 (9.4) | 0.374 | 12 (12.1) | 43 (10.9) | 0.721 |
| Creatinine > 1.2 mg/dL, n (%) * | 47 (47.5) | 649 (41.0) | 0.204 | 47 (47.5) | 179 (45.2) | 0.685 |
| Hemoglobin < 8 g/dL, n (%) * | 8 (8.1) | 97 (6.1) | 0.436 | 8 (8.1) | 28 (7.1) | 0.729 |
| Platelet < 150 1000/μL, n (%) * | 32 (32.3) | 408 (25.8) | 0.150 | 32 (32.3) | 110 (27.8) | 0.371 |
| Total bilirubin > 1.4 mg/dL, n (%) * | 26 (26.3) | 322 (20.3) | 0.158 | 26 (26.3) | 87 (22.0) | 0.363 |
VAP, ventilator-associated pneumonia; SD, standard deviation; BMI, body mass index; ER, emergency room; ICU, intensive care unit; SOFA, Sequential Organ Failure Assessment; MV, mechanical ventilation; ECMO, extracorporeal membrane oxygenation; Rx, treatment and medications; APP, antipseudomonal penicillin; APC, antipseudomonal cephalosporin; IMS; immunosuppressive agents; ASA, American Society of Anesthesiologists; HPB, Hepato-biliary-pancrease; PaO2/FiO2, partial pressure of oxygen in arterial blood/fraction of inspired oxygen; ALT, Alanine transaminase. * Upon ICU admission. ** Referred to unstable vital signs during operation. a Exposed within last 14 day. b Used within the last 30 days. c Dose ≥ 10 mg/day prednisolone-equivalent and ≥7 days.