Characteristics of eligible total knee arthroplasty recipients
| Characteristic | No. (%) of patients* | Standardized difference | ||
|---|---|---|---|---|
| All patients n = 70 725 | Emergency department visit n = 11 224 | No emergency department visit n = 59 501 | ||
| Age, yr, median (IQR) | 67 (61–74) | 68 (61–75) | 67 (61–74) | 0.09 |
| Sex | ||||
| Female | 43 915 (62.1) | 6543 (58.3) | 37 372 (62.8) | 0.09 |
| Male | 26 810 (37.9) | 4681 (41.7) | 22 129 (37.2) | 0.09 |
| Rural residence | 11 505 (16.3) | 2563 (22.8) | 8942 (15.0) | 0.20 |
| Ethnic concentration quintile†‡ | ||||
| 1 (lowest) | 17 345 (24.7) | 3331 (30.0) | 14 014 (23.7) | 0.14 |
| 2 | 15 976 (22.7) | 2561 (23.1) | 13 415 (22.7) | 0.01 |
| 3 | 13 634 (19.4) | 2036 (18.3) | 11 598 (19.6) | 0.03 |
| 4 | 11 789 (16.8) | 1616 (14.5) | 10 173 (17.2) | 0.07 |
| 5 (highest) | 11 559 (16.4) | 1564 (14.1) | 9995 (16.9) | 0.08 |
| Instability quintile†‡ | ||||
| 1 (lowest) | 12 143 (17.3) | 1700 (15.3) | 10 443 (17.6) | 0.06 |
| 2 | 14 062 (20.0) | 2149 (19.3) | 11 913 (20.1) | 0.02 |
| 3 | 14 783 (21.0) | 2372 (21.4) | 12 411 (21.0) | 0.01 |
| 4 | 14 605 (20.8) | 2526 (22.7) | 12 079 (20.4) | 0.06 |
| 5 (highest) | 14 710 (20.9) | 2361 (21.3) | 12 349 (20.9) | 0.01 |
| Dependency quintile†‡ | ||||
| Lowest | 10 123 (14.4) | 1407 (12.7) | 8716 (14.7) | 0.06 |
| 2 | 11 831 (16.8) | 1702 (15.3) | 10 129 (17.1) | 0.05 |
| 3 | 13 216 (18.8) | 1975 (17.8) | 11 241 (19.0) | 0.03 |
| 4 | 14 776 (21.0) | 2466 (22.2) | 12 310 (20.8) | 0.03 |
| 5 (highest) | 20 357 (29.0) | 3558 (32.0) | 16 799 (28.4) | 0.08 |
| Deprivation quintile†‡ | ||||
| 1 (lowest) | 14 270 (20.3) | 2118 (19.1) | 12 152 (20.5) | 0.04 |
| 2 | 14 722 (20.9) | 2187 (19.7) | 12 535 (21.2) | 0.04 |
| 3 | 14 300 (20.3) | 2339 (21.1) | 11 961 (20.2) | 0.02 |
| 4 | 14 267 (20.3) | 2328 (21.0) | 11 939 (20.2) | 0.02 |
| 5 (highest) | 12 744 (18.1) | 2136 (19.2) | 10 608 (17.9) | 0.03 |
| Income quintile‡ | ||||
| 1 (lowest) | 12 129 (17.2) | 2152 (19.2) | 9977 (16.8) | 0.06 |
| 2 | 14 566 (20.6) | 2359 (21.1) | 12 207 (20.6) | 0.01 |
| 3 | 14 652 (20.8) | 2221 (19.8) | 12 431 (20.9) | 0.03 |
| 4 | 14 458 (20.5) | 2235 (20.0) | 12 223 (20.6) | 0.02 |
| 5 (highest) | 14 773 (20.9) | 2235 (20.0) | 12 538 (21.1) | 0.03 |
| Comorbidities | ||||
| Asthma | 3268 (4.6) | 630 (5.6) | 2638 (4.4) | 0.05 |
| Coronary artery disease | 2186 (3.1) | 425 (3.8) | 1761 (3.0) | 0.05 |
| Congestive heart failure | 3271 (4.6) | 701 (6.2) | 2570 (4.3) | 0.09 |
| Chronic obstructive pulmonary disease | 13 148 (18.6) | 2521 (22.5) | 10 627 (17.9) | 0.11 |
| Counselled about smoking cessation | 3352 (4.7) | 595 (5.3) | 2757 (4.6) | 0.03 |
| Diabetes | 20 508 (29.0) | 3409 (30.4) | 17 099 (28.7) | 0.04 |
| Complicated diabetes | 3650 (5.2) | 743 (6.6) | 2907 (4.9) | 0.07 |
| Hypertension | 51 267 (72.5) | 8358 (74.5) | 42 909 (72.1) | 0.05 |
| Frailty | 3407 (4.8) | 635 (5.7) | 2772 (4.7) | 0.05 |
| Charlson Comorbidity Index score | ||||
| 0 | 50 204 (71.0) | 7596 (67.7) | 42 608 (71.6) | 0.09 |
| 1 | 13 274 (18.8) | 2252 (20.1) | 11 022 (18.5) | 0.04 |
| 2 | 4799 (6.8) | 863 (7.7) | 3936 (6.6) | 0.04 |
| ≥ 3 | 2448 (3.5) | 513 (4.6) | 1935 (3.2) | 0.07 |
| Admission characteristics | ||||
| Hospital volume, median (IQR) | 429 (315–607) | 427 (311–597) | 429 (315–609) | 0.04 |
| Surgeon volume, median (IQR) | 104 (72–138) | 104 (71–137) | 104 (72–138) | 0.01 |
| General anesthesia | 11 470 (16.2) | 1859 (16.6) | 9611 (16.2) | 0.01 |
| Change in annual health care costs, 2013 dollars, median (IQR) | −586 (−2356 to 5248) | 682 (−1673 to 8227) | −771 (−2449 to 4330) | 0.30 |
| Readmission within 30 d | 156 (0.2) | 70 (0.6) | 86 (0.1) | 0.08 |