Table 2. Characteristics of Hip Fracture Cohort Before and After Matching.
| Characteristic | Prior to Matching | After Matching | |||||
|---|---|---|---|---|---|---|---|
| All Patients | Overlapping | Nonoverlapping | P Value | Overlapping | Nonoverlapping | Standardized Difference | |
| Patients, No. | 38 008 | 960 | 37 048 | 855 | 855 | ||
| Demographics | |||||||
| Age, median (IQR), y | 84 (77-89) | 84 (77-89) | 84 (77-89) | >.99 | 84 (77-89) | 84 (78-89) | 0 |
| Female, No. (%) | 27 101 (71.3) | 700 (72.9) | 26 401 (71.3) | .26 | 631 (73.8) | 631 (73.8) | 0 |
| Income quintile, No. (%) | <.001 | ||||||
| Lowest | 8486 (22.3) | 222 (23.1) | 8264 (22.3) | 187 (21.9) | 185 (21.6) | 0.01 | |
| 2 | 7703 (20.3) | 185 (19.3) | 7518 (20.3) | 163 (19.1) | 169 (19.8) | 0.02 | |
| 3 | 7335 (19.3) | 161 (16.8) | 7174 (19.4) | 150 (17.5) | 152 (17.8) | 0.01 | |
| 4 | 7315 (19.2) | 164 (17.1) | 7151 (19.3) | 147 (17.2) | 157 (18.4) | 0.03 | |
| Highest | 6978 (18.4) | 217 (22.6) | 6761 (18.2) | 198 (23.2) | 181 (21.2) | 0.05 | |
| Nursing home, No. (%) | 3923 (10.3) | 89 (9.3) | 3834 (10.3) | .28 | 80 (9.4) | 81 (9.5) | 0 |
| Comorbidities, No. (%) | |||||||
| Previous myocardial infarction | 2995 (7.9) | 52 (5.4) | 2943 (7.9) | .004 | 48 (5.6) | 76 (8.9) | 0.13 |
| Congestive heart failure | 9082 (23.9) | 224 (23.3) | 8858 (23.9) | .68 | 201 (23.5) | 211 (24.7) | 0.03 |
| Cerebrovascular disease | 2837 (7.5) | 68 (7.1) | 2769 (7.5) | .65 | 62 (7.3) | 69 (8.1) | 0.03 |
| COPD | 7575 (19.9) | 180 (18.8) | 7395 (20.0) | .35 | 159 (18.6) | 151 (17.7) | 0.02 |
| Dementia | 11 635 (30.6) | 286 (29.8) | 11 349 (30.6) | .58 | 260 (30.4) | 269 (31.5) | 0.02 |
| Diabetes | 11 389 (30.0) | 286 (29.8) | 11 103 (30.0) | .91 | 252 (29.5) | 236 (27.6) | 0.04 |
| Chronic renal failure | 4901 (12.9) | 119 (12.4) | 4782 (12.9) | .64 | 104 (12.2) | 97 (11.3) | 0.03 |
| Frailty | 6911 (18.2) | 167 (17.4) | 6744 (18.2) | .52 | 151 (17.7) | 160 (18.7) | 0.03 |
| Charlson score, No. (%) | .54 | ||||||
| No prior admission | 16 920 (44.5) | 421 (43.9) | 16 499 (44.5) | 365 (42.7) | 359 (42.0) | 0.01 | |
| 0 | 6160 (16.2) | 162 (16.9) | 5998 (16.2) | 153 (17.9) | 170 (19.9) | 0.05 | |
| 1 | 5564 (14.6) | 135 (14.1) | 5429 (14.7) | 121 (14.2) | 109 (12.7) | 0.04 | |
| 2 | 3582 (9.4) | 104 (10.8) | 3478 (9.4) | 92 (10.8) | 84 (9.8) | 0.03 | |
| ≥3 or more | 5782 (15.2) | 138 (14.4) | 5644 (15.2) | 124 (14.5) | 133 (15.6) | 0.03 | |
| Fracture characteristics, No. (%) | |||||||
| Fracture type | .10 | ||||||
| Femoral neck | 19 300 (50.8) | 516 (53.8) | 18 784 (50.7) | 475 (55.6) | 454 (53.1) | 0.05 | |
| Intertrochanteric | 16 950 (44.6) | 409 (42.6) | 16 541 (44.6) | 357 (41.8) | 373 (43.6) | 0.04 | |
| Subtrochanteric | 1758 (4.6) | 35 (3.6) | 1723 (4.7) | 23 (2.7) | 28 (3.3) | 0.03 | |
| Fixation | .01 | ||||||
| Hemiarthroplasty | 15 245 (40.1) | 424 (44.2) | 14 821 (40.0) | 388 (45.4) | 388 (45.4) | 0 | |
| Screw | 17 373 (45.7) | 395 (41.1) | 16 978 (45.8) | 360 (42.1) | 360 (42.1) | 0 | |
| Intramedullary nail | 5390 (14.2) | 141 (14.7) | 5249 (14.2) | 107 (12.5) | 107 (12.5) | 0 | |
| Admission characteristic | |||||||
| Hours from ED to OR median (IQR) | 31 (21-50) | 36 (22-51) | 31 (21-50) | .01 | 35 (22-51) | 35 (23-51) | 0.04 |
| Teaching hospital, No. (%) | 10 442 (27.5) | 690 (71.9) | 9752 (26.3) | <.001 | 601 (70.3) | 601 (70.3) | 0 |
| Surgical assistant, No. (%) | 22 278 (58.6) | 526 (54.8) | 21 752 (58.7) | .02 | 458 (53.6) | 441 (51.6) | 0.04 |
| Family physician, No. (%) | 15 698 (41.3) | 171 (17.8) | 15 527 (41.9) | <.001 | 161 (18.8) | 178 (20.8) | 0.05 |
| Nonorthopedic surgeon, No. (%) | 2820 (7.4) | 21 (2.2) | 2799 (7.6) | <.001 | 18 (2.1) | 24 (2.8) | 0.05 |
| Orthopedic surgeon, No. (%) | 3960 (10.4) | 337 (35.1) | 3623 (9.8) | <.001 | 282 (33.0) | 244 (28.5) | 0.10 |
| Years in practice median (IQR) | 5 (0-27) | 0 (0-5) | 6 (0-27) | <.001 | 0 (0-4) | 0 (0-4) | 0.03 |
| Surgeon volume median (IQR) | 36 (25-49) | 39 (24-55) | 36 (25-49) | <.001 | 40 (27-56) | 39 (28-55) | 0.01 |
| Hospital volume median (IQR) | 206 (157-262) | 264 (187-320) | 204 (157-261) | <.001 | 268 (195-339) | 263 (195-342) | 0.02 |
| Characteristic | Total | Overlapping | Nonoverlapping | P Value | Overlapping | Nonoverlapping | P Value |
| Surgical complication, No. (%) | 2360 (6.2) | 80 (8.3) | 2280 (6.2) | .006 | 87 (10.2) | 53 (6.2) | .001 |
| Dislocation, No. (%) | 188 (0.5) | NA | 184 (0.5) | .73 | NA | NA | .74 |
| Infection, No. (%) | 1643 (4.3) | 60 (6.3) | 1583 (4.3) | .003 | 57 (6.7) | 36 (4.2) | .001 |
| Revision, No. (%) | 1802 (4.7) | 65 (6.8) | 1737 (4.7) | .003 | 61 (7.1) | 40 (4.7) | .02 |
| Duration of surgery, median (IQR), min | 95 (76-120) | 117 (93-140) | 95 (76-119) | <.001 | 116 (92-139) | 110 (90-131) | .003 |
| Death within 90 d, No. (%) | 5336 (14.0) | 138 (14.4) | 5198 (14.0) | .76 | 127 (15.0) | 107 (12.6) | .15 |
Abbreviations: ED, emergency department; IQR, interquartile range; NA, not applicable (<5 events); OR operating room.