Hospital characteristics for patients undergoing THA according to hospital safety net burden category
| Characteristic | Overall, n (%) | Low burden, n (%) | Medium burden, n (%) | High burden, n (%) | P value |
| Hospital volume | <0.0001 | ||||
| First quartile | 125 767 (25.1) | 35 778 (17.8) | 55 816 (26.6) | 34 173 (38.2) | |
| Second quartile | 124 720 (24.9) | 43 196 (21.5) | 54 040 (25.7) | 27 484 (30.7) | |
| Third quartile | 121 942 (24.4) | 49 791 (24.8) | 57 476 (27.4) | 14 675 (16.4) | |
| Fourth quartile | 127 760 (25.5) | 72 091 (35.9) | 42 610 (20.3) | 13 059 (14.6) | |
| CBSA designation | <0.0001 | ||||
| Non-CBSA | 16 492 (3.3) | 3006 (1.5) | 10 160 (4.8) | 3326 (3.7) | |
| Micropolitan statistical Area | 28 745 (5.7) | 5328 (2.7) | 18 298 (8.7) | 5119 (5.7) | |
| Metropolitan statistical Area | 452 520 (90.5) | 191 558 (95.4) | 180 685 (86.1) | 80 277 (89.8) | |
| Missing | 2432 (0.5) | 964 (0.5) | 799 (0.4) | 669 (0.7) |
P values refer to comparisons between hospital burden categories.
Categorical variables analyzed using the χ2 test.
Per cents may not sum to 100 due to rounding and missing values.
CBSA, core-based statistical area.