Table 1. Characteristics of Study Population (N = 41 537).
| Variable | Population, No. (%) (N = 41 537) | None, No./Total No. (%) (N = 668) | Aspirin Only, No./Total No. (N = 12 831) | Anticoagulant Only, No./Total No. (N = 22 620) | Both, No./Total No. (N = 5418) | P Value of Statistical Tests |
|---|---|---|---|---|---|---|
| Continuous variables | ||||||
| Age, y, No. (mean [SD]) | 41 537 (65.8 [9.8]) | 668 (65.7 [10.2]) | 12 831 (65.6 [9.8]) | 22 620 (65.5 [9.8]) | 5418 (67.4 [9.4]) | <.001a |
| BMI, No. (mean [SD]) | 41 369 (33.1 [6.9]) | 664 (32.6 [6.6]) | 12 783 (32.7 [6.7]) | 22 523 (33.4 [7.1]) | 5399 (33.1 [6.8]) | <.001a |
| Categorical variables | ||||||
| African American race | 3230 (7.8) | 54/668 (8.1) | 855/12 831 (6.7) | 1840/22 620 (8.1) | 481/5418 (8.9) | <.001b |
| Male | 14 966 (36.1) | 261/668 (39.1) | 4882/12 822 (38.1) | 7499/22 605 (33.2) | 2324/5418 (42.9) | <.001b |
| Marital status (married) | 27 462 (66.2) | 453/667 (67.9) | 8658/12 795 (67.7) | 14 652/22 595 (64.8) | 3699/5415 (68.3) | <.001b |
| Surgical approach | ||||||
| Medial parapatellar | 34 185 (82.3) | 542/668 (81.1) | 10 424/12 831 (81.2) | 19 158/22 620 (84.7) | 4061/5418 (75.0) | <.001b |
| Lateral parapatellar | 181 (0.4) | <10c | 96/12 831 (0.8) | 52/22 620 (0.2) | 27/5418 (0.5) | |
| Midvastus | 5814 (14.0) | 90/668 (13.5) | 1774/12 831 (13.8) | 2800/22 620 (12.4) | 1150/5418 (21.2) | |
| Subvastus | 1016 (2.5) | 15/668 (2.3) | 420/12 831 (3.3) | 479/22 620 (2.1) | 102/5418 (1.9) | |
| Other | 341 (0.8) | 15/668 (2.3) | 117/12 831 (0.9) | 131/22 620 (0.6) | 78/5418 (1.4) | |
| General anesthesia | 13 383 (32.2) | 265/667 (39.7) | 4211/12 819 (32.8) | 7021/22 617 (31.0) | 1886/5418 (34.8) | <.001b |
| ASA status | ||||||
| I | 702 (1.7) | <10c | 250/12 806 (2.0) | 338/22 599 (1.5) | 107/5416 (2.0) | <.001b |
| II | 21 837 (52.6) | 322/667 (48.3) | 6986/12 806 (54.6) | 11 873/22 599 (52.5) | 2656/5416 (49.0) | |
| III | 18 480 (44.5) | 323/667 (48.4) | 5438/12 806 (42.5) | 10 130/22 599 (44.8) | 2589/5416 (47.8) | |
| IV | 469 (1.1) | 15/667 (2.3) | 132/12 806 (1.0) | 258/22 599 (1.1) | 64/5416 (1.2) | |
| Bleeding disorder | 472 (1.1) | 36/667 (5.4) | 136/12 799 (1.1) | 232/22 596 (1.0) | 68/5414 (1.3) | <.001b |
| VTE | 2320 (5.6) | 39/667 (5.9) | 399/12 803 (3.1) | 1532/22 589 (6.8) | 350/5409 (6.5) | <.001b |
| Tranexamic acid given | 25 698 (61.9) | 381/668 (57.0) | 9135/12 831 (71.2) | 12 678/22 620 (56.0) | 3504/5418 (64.7) | <.001b |
| Intermittent pneumatic compression | 36 113 (86.9) | 607/668 (90.9) | 11 755/12 831 (91.6) | 19 670/22 620 (87.0) | 4081/5418 (75.3) | <.001b |
Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); VTE, venous thromboembolism.
a
Kruskal-Wallis Test: nonparametric testing of continuous variables for comparing independent group.
b
Pearson χ2 tests of homogeneity/independence for categorical variables with prophylaxis groups.
c
Actual numbers for cell size less than 10 are not shown.