Baseline characteristics and perioperative factors of study patients with or without postoperative anti-PF4/heparin antibody seroconversion based on univariate analysis
| . | Seroconversion (+), n = 262 (12.7%) . | Seroconversion (−), n = 1807 (87.3%) . | P . | Missing data . |
|---|---|---|---|---|
| Demographic variables, n (%) | ||||
| Age ≥75 y | 117 (44.7) | 784 (43.4) | .698 | 0 |
| Female gender | 245 (93.5) | 1488 (82.3) | <.001 | 0 |
| Body mass index ≥30 kg/m2 | 21 (8.0) | 175 (9.7) | .382 | 5 |
| Preoperative laboratory data, n (%) | ||||
| Red cell count ≥6 × 1012/L (male) or ≥5.5 × 1012/L (female) | 0 (0) | 4 (0.2) | 1.000 | 0 |
| White cell count ≥10 × 109/L | 7 (2.7) | 54 (3.0) | 1.000 | 0 |
| Platelet count ≥400 × 109/L or <100 × 109/L | 9 (3.4) | 82 (4.5) | .519 | 0 |
| Serum albumin <3.5 g/dL | 30 (11.5) | 269 (14.9) | .139 | 0 |
| e-GFR <60 mL/min/1.73m2 | 62 (23.7) | 369 (20.5) | .232 | 3 |
| Preoperative anti-PF4/heparin antibodies: positive | 1 (0.4) | 22 (1.2) | .347 | 9 |
| Medical history, n (%) | ||||
| Hypertension | 117 (54.7) | 859 (58.0) | .351 | 373 |
| Diabetes mellitus | 29 (11.8) | 221 (13.1) | .591 | 113 |
| Dyslipidemia | 42 (17.2) | 246 (14.6) | .277 | 136 |
| Atrial fibrillation | 3 (1.4) | 34 (2.3) | .615 | 377 |
| Malignancy | 3 (1.1) | 27 (1.5) | 1.000 | 0 |
| Rheumatoid arthritis | 21 (8.0) | 217 (12.0) | .058 | 0 |
| Venous thromboembolism | 6 (2.3) | 13 (0.6) | .025 | 0 |
| Operative variables, n (%) | ||||
| Type of surgery: TKA | 187 (71.4) | 1057 (58.5) | <.001 | 0 |
| Operation time ≥120 min | 128 (48.9) | 944 (52.2) | .305 | 0 |
| Type of anesthesia | ||||
| General | 80 (30.5) | 545 (30.2) | .902 | 0 |
| Combination of epidural and general | 107 (40.8) | 858 (47.5) | .044 | 0 |
| Epidural | 5 (1.9) | 65 (3.6) | .200 | 0 |
| Spinal | 70 (26.7) | 339 (18.8) | .003 | 0 |
| Postoperative thromboprophylaxis, n (%) | ||||
| Drugs | ||||
| UFH | 17 (6.5) | 85 (4.7) | .212 | 0 |
| LMWH | 40 (15.3) | 320 (17.7) | .330 | 0 |
| Fondaparinux | 96 (36.6) | 479 (26.5) | .001 | 0 |
| Antiplatelet drug | 12 (4.6) | 76 (4.2) | .779 | 0 |
| DMT (foot pump or IPCD) | 230 (87.8) | 1352 (74.8) | <.001 | 0 |
| GCSs | 198 (75.6) | 1616 (89.4) | <.001 | 0 |
| . | Seroconversion (+), n = 262 (12.7%) . | Seroconversion (−), n = 1807 (87.3%) . | P . | Missing data . |
|---|---|---|---|---|
| Demographic variables, n (%) | ||||
| Age ≥75 y | 117 (44.7) | 784 (43.4) | .698 | 0 |
| Female gender | 245 (93.5) | 1488 (82.3) | <.001 | 0 |
| Body mass index ≥30 kg/m2 | 21 (8.0) | 175 (9.7) | .382 | 5 |
| Preoperative laboratory data, n (%) | ||||
| Red cell count ≥6 × 1012/L (male) or ≥5.5 × 1012/L (female) | 0 (0) | 4 (0.2) | 1.000 | 0 |
| White cell count ≥10 × 109/L | 7 (2.7) | 54 (3.0) | 1.000 | 0 |
| Platelet count ≥400 × 109/L or <100 × 109/L | 9 (3.4) | 82 (4.5) | .519 | 0 |
| Serum albumin <3.5 g/dL | 30 (11.5) | 269 (14.9) | .139 | 0 |
| e-GFR <60 mL/min/1.73m2 | 62 (23.7) | 369 (20.5) | .232 | 3 |
| Preoperative anti-PF4/heparin antibodies: positive | 1 (0.4) | 22 (1.2) | .347 | 9 |
| Medical history, n (%) | ||||
| Hypertension | 117 (54.7) | 859 (58.0) | .351 | 373 |
| Diabetes mellitus | 29 (11.8) | 221 (13.1) | .591 | 113 |
| Dyslipidemia | 42 (17.2) | 246 (14.6) | .277 | 136 |
| Atrial fibrillation | 3 (1.4) | 34 (2.3) | .615 | 377 |
| Malignancy | 3 (1.1) | 27 (1.5) | 1.000 | 0 |
| Rheumatoid arthritis | 21 (8.0) | 217 (12.0) | .058 | 0 |
| Venous thromboembolism | 6 (2.3) | 13 (0.6) | .025 | 0 |
| Operative variables, n (%) | ||||
| Type of surgery: TKA | 187 (71.4) | 1057 (58.5) | <.001 | 0 |
| Operation time ≥120 min | 128 (48.9) | 944 (52.2) | .305 | 0 |
| Type of anesthesia | ||||
| General | 80 (30.5) | 545 (30.2) | .902 | 0 |
| Combination of epidural and general | 107 (40.8) | 858 (47.5) | .044 | 0 |
| Epidural | 5 (1.9) | 65 (3.6) | .200 | 0 |
| Spinal | 70 (26.7) | 339 (18.8) | .003 | 0 |
| Postoperative thromboprophylaxis, n (%) | ||||
| Drugs | ||||
| UFH | 17 (6.5) | 85 (4.7) | .212 | 0 |
| LMWH | 40 (15.3) | 320 (17.7) | .330 | 0 |
| Fondaparinux | 96 (36.6) | 479 (26.5) | .001 | 0 |
| Antiplatelet drug | 12 (4.6) | 76 (4.2) | .779 | 0 |
| DMT (foot pump or IPCD) | 230 (87.8) | 1352 (74.8) | <.001 | 0 |
| GCSs | 198 (75.6) | 1616 (89.4) | <.001 | 0 |
This table shows the differences in baseline characteristics and perioperative factors between the patients who developed anti-PF4/heparin IgG/A/M antibody seroconversion (+; n = 262, 12.7%), assessed by an immunoassay, and those who did not (−; n = 1807, 87.3%) in major orthopedic surgery (TKA or THA). Seroconversion was defined as a positive test result on POD 10 corresponding to a negative result before surgery. In addition, patients who tested positive before surgery were considered seroconverters if their blood sample on POD 10 was positive and had a twofold-or-more increase in OD value. Statistical analysis was performed with the χ2 test. When the sample size of a cell in a 2-by-2 table was <10, Fisher’s exact test was used. The number of the patients who lacked a variable is listed in the “Missing data” column.
e-GFR, estimated glomerular filtration rate.