Table 1.
Baseline characteristics
| Characteristic | Control (N = 117,455) | Intervention (N = 121,431) |
|---|---|---|
| Site, n (%) | ||
| A | 6,950 (6) | 7,388 (6) |
| B | 96,275 (82) | 100,729 (83) |
| C | 7,846 (7) | 7,726 (6) |
| D | 6,384 (5) | 5,588 (5) |
| Age in years, n (%) | ||
| 18–39 | 21,237 (18) | 22,105 (18) |
| 40–60 | 45,032 (38) | 44,995 (37) |
| >60 | 51,186 (44) | 54,331 (45) |
| Sex,* n (%) | ||
| Female | 67,915 (58) | 69,458 (57) |
| Male | 49,534 (42) | 51,965 (43) |
| Charlson Comorbidity Index, n (%) | ||
| 0 | 75,106 (64) | 77,973 (64) |
| 1 | 20,675 (18) | 21,193 (17) |
| 2 | 11,451 (10) | 11,760 (10) |
| 3+ | 10,223 (9) | 10,505 (9) |
| Primary insurance at index, n (%) | ||
| Medicare | 44,362 (38) | 46,479 (38) |
| Medicaid/state-subsidized | 5,546 (5) | 6,510 (5) |
| Commercial | 65,375 (56) | 66,368 (55) |
| VA | 117 (0) | 131 (0) |
| Self-pay | 731 (1) | 570 (0) |
| Unknown or not reported | 1,324 (1) | 1,373 (1) |
| Socioeconomic index,† mean±SD | 57±6 | 57±7 |
| Prior injection, n (%) | 1,399 (1) | 966 (1) |
| Prior surgery, n (%) | 90 (0.1) | 89 (0.1) |
*
Does not include 14 patients with other or unknown sex.
†
Does not include 6,810 (3%) patients with unknown socioeconomic index.