Baseline characteristics of patients who underwent outpatient total knee or hip arthroplasty by anesthesia type
| Characteristic | Total | Anesthesia type | P value | |
| Neuraxial | General | |||
| n=11 523 | n=10 003 | n=1520 | ||
| Mean age in years (SD) | 68.0 (8.9) | 68.2 (8.8) | 67.3 (9.2) | <0.01* |
| Sex, n (%) | 0.79 | |||
| Male | 4577 (39.7) | 3978 (39.8) | 599 (39.4) | |
| Female | 6946 (60.3) | 6025 (60.2) | 921 (60.6) | |
| Race/ethnicity, n (%) | <0.01 | |||
| Non-Hispanic White | 7844 (68.1) | 6830 (68.3) | 1014 (66.7) | |
| Asian | 931 (8.1) | 864 (8.6) | 67 (4.4) | |
| Black | 720 (6.3) | 581 (5.8) | 139 (9.1) | |
| Hispanic | 1515 (13.2) | 1280 (12.8) | 235 (15.5) | |
| Other | 513 (4.5) | 448 (4.5) | 65 (4.3) | |
| BMI††, n (%) | <0.01 | |||
| Normal | 1727 (15.0) | 1549 (15.5) | 178 (11.7) | |
| Overweight | 3967 (34.4) | 3488 (34.9) | 479 (31.5) | |
| Obese | 5828 (50.6) | 4965 (49.6) | 863 (56.8) | |
| ASA class, n (%) | <0.01 | |||
| I | 172 (1.5) | 165 (1.7) | 7 (0.5) | |
| II | 6874 (59.7) | 6182 (61.8) | 692 (45.5) | |
| III | 4396 (38.2) | 3608 (36.1) | 788 (51.8) | |
| IV | 81 (0.7) | 48 (0.5) | 33 (2.2) | |
| Surgery type, n (%) | <0.01 | |||
| Knee | 9866 (85.6) | 8638 (86.4) | 1228 (80.8) | |
| Hip | 1657 (14.4) | 1365 (13.7) | 292 (19.2) | |
| Comorbidity score‡‡, n (%) | 0.01 | |||
| 0 | 4412 (38.3) | 3865 (38.6) | 547 (36.0) | |
| 1–2 | 4854 (42.1) | 4223 (42.2) | 631 (41.5) | |
| 3+ | 2257 (19.6) | 1915 (19.1) | 342 (22.5) | |
| Laterality, n (%) | 0.72 | |||
| Left | 5470 (47.5) | 4755 (47.5) | 715 (47.0) | |
| Right | 6053 (52.5) | 5248 (52.5) | 805 (53.0) | |
| Mean hemoglobin before surgery within 3 months of surgery date§§ (SD) | 13.6 (1.4) | 13.7 (1.4) | 13.5 (1.5) | <0.01* |
*P value calculated with Student t-test.
†0.008% missing BMI (one patient).
‡Charlson comorbidity index used as comorbidity score.
§10.5% missing last hemoglobin before surgery (1214 patients).
BMI, body mass index; ASA, American Society of Anesthesiologists.