Table 3.
Comparison of demographic characteristic of recipients of total hip arthroplasty before and after matching by surgeon volume
| Before matching | After matching | ||||||
|---|---|---|---|---|---|---|---|
| ≤35 procedures (9494 patients) | >35 procedures (28 387 patients) | Standardized difference | ≤35 procedures (6716 patients) | >35 procedures (6716 patients) | Standardized difference | ||
| Median (IQR) age (years) | 70 (61-76) | 67 (58-75) | 0.20 | 69 (61-76) | 70 (61-76) | 0.03 | |
| No (%) of women | 5290 (55.9) | 15 082 (53.2) | 0.05 | 3730 (55.7) | 3716 (55.4) | 0.00 | |
| No (%) of men | 4170 (44.1) | 13 253 (46.8) | 2965 (44.3) | 2989 (44.6) | |||
| Mean (SD) rurality index | 14.77 (18.79) | 13.01 (18.38) | 0.10 | 12.28 (17.22) | 12.08 (16.81) | 0.01 | |
| No (%) by fifth of income: | |||||||
| Lowest | 1674 (17.7) | 4440 (15.7) | 0.10 | 1106 (16.5) | 1122 (16.7) | 0.01 | |
| 2 | 1966 (20.8) | 5291 (18.7) | 1385 (20.6) | 1394 (20.8) | |||
| 3 | 1898 (20.0) | 5477 (19.4) | 1341 (20.0) | 1346 (20.0) | |||
| 4 | 1924 (20.3) | 5985 (21.2) | 1413 (21.0) | 1416 (21.1) | |||
| Highest | 2011 (21.2) | 7094 (25.1) | 1471 (21.9) | 1438 (21.4) | |||
| Median (IQR) income fifth | 3 (2-4) | 3(2-5) | 0.10 | 3 (2-4) | 3 (2-4) | 0.01 | |
| No (%) by fifth of ethnic concentration: | |||||||
| Lowest | 1595 (19.8) | 4981 (19.2) | 0.05 | 1269 (18.9) | 1221 (18.2) | 0.04 | |
| 2 | 1613 (20.1) | 5717 (22.0) | 1356 (20.2) | 1279 (19.0) | |||
| 3 | 1669 (20.8) | 5619 (21.6) | 1412 (21.0) | 1408 (21.0) | |||
| 4 | 1481 (18.4) | 5248 (20.2) | 1278 (19.0) | 1290 (19.2) | |||
| Highest | 1682 (20.9) | 4413 (17.0) | 1401 (20.9) | 1518 (22.6) | |||
| Median (IQR) ethnic concentration | 3 (2-4) | 3 (2-4) | 0.05 | 3 (2-4) | 3 (2-4) | 0.04 | |
| No (%) by fifth of instability index: | |||||||
| Lowest | 1570 (19.5) | 5503 (21.2) | 0.01 | 1338 (19.9) | 1365 (20.3) | 0.01 | |
| 2 | 1813 (22.5) | 5682 (21.9) | 1514 (22.5) | 1508 (22.5) | |||
| 3 | 1612 (20.0) | 5030 (19.4) | 1313 (19.6) | 1314 (19.6) | |||
| 4 | 1581 (19.7) | 4738 (18.2) | 1303 (19.4) | 1313 (19.6) | |||
| Highest | 1464 (18.2) | 5025 (19.3) | 1248 (18.6) | 1216 (18.1) | |||
| Median (IQR) instability index | 3 (2-4) | 3 (2-4) | 0.01 | 3 (2-4) | 3 (2-4) | 0.01 | |
| No (%) by fifth of dependency index: | |||||||
| Lowest | 893 (11.1) | 3331 (12.8) | 0.07 | 773 (11.5) | 772 (11.5) | 0.01 | |
| 2 | 1381 (17.2) | 4631 (17.8) | 1163 (17.3) | 1193 (17.8) | |||
| 3 | 1560 (19.4) | 5219 (20.1) | 1302 (19.4) | 1330 (19.8) | |||
| 4 | 1697 (21.1) | 5430 (20.9) | 1390 (20.7) | 1353 (20.1) | |||
| Highest | 2509 (31.2) | 7367 (28.4) | 2088 (31.1) | 2068 (30.8) | |||
| Median (IQR) dependency index | 4 (2-5) | 3 (2-5) | 0.07 | 4 (2-5) | 4 (2-5) | 0.01 | |
| No (%) by fifth of deprivation index: | |||||||
| Lowest | 1747 (21.7) | 7225 (27.8) | 0.15 | 1499 (22.3) | 1468 (21.9) | 0.02 | |
| 2 | 1904 (23.7) | 6289 (24.2) | 1604 (23.9) | 1557 (23.2) | |||
| 3 | 1847 (23.0) | 5426 (20.9) | 1537 (22.9) | 1548 (23.0) | |||
| 4 | 1434 (17.8) | 4205 (16.2) | 1192 (17.7) | 1228 (18.3) | |||
| Highest | 1108 (13.8) | 2833 (10.9) | 884 (13.2) | 915 (13.6) | |||
| Median (IQR) deprivation index | 3 (2-4) | 2 (1-4) | 0.15 | 3 (2-4) | 3 (2-4) | 0.02 | |