Covariate balance (self-reported information from the 45 and Up Study baseline questionnaire) by TKA status and type of matching
| Variable | Unmatched | Propensity score matched | Age, sex, arthritis matched | ||||
|---|---|---|---|---|---|---|---|
| TKA | No TKA | No TKA-TKA (%) | No TKA | No TKA-TKA | No TKA | No TKA-TKA | |
| Age (years) | |||||||
| 45–49 | 20 (0.7%) | 28 985 (14.3%) | −13.6 | 117 (0.8%) | −0.1 | 100 (0.7%) | 0 |
| 50–54 | 60 (2.1%) | 35 560 (17.6%) | −15.5% | 282 (2.0%) | 0.1% | 300 (2.1%) | 0% |
| 55–59 | 168 (5.8%) | 36 796 (18.2%) | −12.4% | 780 (5.4%) | 0.4% | 840 (5.8%) | 0% |
| 60–64 | 362 (12.4%) | 31 346 (15.5%) | −3.1% | 1761 (12.2%) | 0.2% | 1810 (12.4%) | 0% |
| 65–69 | 500 (17.1%) | 24 788 (12.3%) | 4.8% | 2564 (17.7%) | −0.6% | 2500 (17.1%) | 0% |
| 70–74 | 546 (18.7%) | 16 741 (8.3%) | 10.4% | 2776 (19.2%) | −0.5% | 2730 (18.7%) | 0% |
| 75–79 | 493 (16.9%) | 11 443 (5.7%) | 11.2% | 2389 (16.5%) | 0.4% | 2465 (16.9%) | 0% |
| 80–84 | 572 (19.6%) | 11 797 (5.8%) | 13.8% | 2829 (19.6%) | 0% | 2860 (19.6%) | 0% |
| 85+ | 195 (6.7%) | 4,776 (2.4%) | 4.3% | 956 (6.6%) | 0.1% | 975 (6.7%) | 0% |
| Sex | |||||||
| Male | 1468 (50.3%) | 94847 (47.8%) | −0.9% | 7369 (51.0%) | −0.7% | 7340 (50.3%) | 0% |
| Female | 1448 (49.7%) | 107385 (52.2%) | 0.9% | 7085 (49.0%) | 0.7% | 7240 (49.7%) | 0% |
| Education level | |||||||
| Less than high school | 1319 (46.2%) | 64 554 (32.3%) | 13.9% | 6622 (46.8%) | −0.6% | 5964 (41.7%) | 4.5% |
| High school | 243 (8.5%) | 19 970 (10.0%) | −1.5% | 1216 (8.6%) | −0.1% | 1355 (9.5%) | −1% |
| Post high school | 947 (33.2%) | 65 373 (32.7%) | 0.5% | 4616 (32.6%) | 0.6% | 4444 (31.1%) | 2.1% |
| University degree | 347 (12.1%) | 49 741 (24.9%) | −12.8% | 1701 (12.0%) | 0.1% | 2542 (17.8%) | −5.7% |
| Income/year | |||||||
| <$20k | 953 (34.8%) | 36 717 (18.7%) | 16.1% | 4629 (34.0%) | 0.8% | 4470 (32.5%) | 2.3% |
| $20–50k | 814 (29.7%) | 51 051 (26.0%) | 3.7% | 4097 (30.1%) | −0.4% | 4199 (30.5%) | −0.8% |
| $50–70 | 170 (6.2%) | 22 623 (11.5%) | −5.3% | 871 (6.4%) | −0.2% | 1006 (7.3%) | −1.1% |
| $70k+ | 230 (8.4%) | 52 793 (26.9%) | −18.5% | 1114 (8.2%) | 0.2% | 1448 (10.5%) | −2.1% |
| Rather not say | 575 (21.0%) | 33 036 (16.8%) | 4.2% | 2894 (21.3%) | −0.3% | 2646 (19.2%) | 1.8% |
| Self-rated health | |||||||
| Excellent or Good | 2109 (74.3%) | 173391 (87.0%) | −12.7% | 10535 (75.0%) | −0.7% | 11281 (79.4%) | −5.1% |
| Poor or very poor | 729 (25.7%) | 25 834 (13.0%) | 12.7% | 3516 (25.0%) | 0.7% | 2922 (20.6%) | 5.1% |
| Number of chronic | |||||||
| No conditions | 277 (9.5%) | 51 722 (25.6%) | −16.1% | 1481 (10.2%) | −0.7% | 2037 (14.0%) | −4.5% |
| Conditions | |||||||
| 1 health condition | 675 (23.1%) | 61 802 (30.6%) | −7.5% | 3301 (22.8%) | 0.3% | 3746 (25.7%) | −2.6% |
| 2 health conditions | 762 (26.1%) | 45 717 (22.6%) | 3.5% | 3822 (26.4%) | −0.3% | 3747 (25.7%) | 0.4% |
| 3 health conditions | 617 (21.2%) | 24 922 (12.3%) | 8.9% | 2810 (19.4%) | 1.8% | 2611 (17.9%) | 3.3% |
| 4+ health conditions | 585 (20.1%) | 18 069 (8.9%) | 11.2% | 3040 (21.0%) | −0.9% | 2439 (16.7%) | 3.4% |
| Recent osteoarthritis | |||||||
| No | 2100 (72.0%) | 189 079 (93.5%) | −21.5% | 10711 (74.1%) | −2.1% | 10500 (72.0%) | 0% |
| Treatment | |||||||
| Yes | 816 (28.0%) | 13 153 (6.5%) | 21.5% | 3743 (25.9%) | 2.1% | 4080 (28.0%) | 0% |
| Private health insurance | |||||||
| Private | 1874 (64.3%) | 131 417 (65.0%) | −0.7% | 9250 (64.0%) | 0.3% | 8420 (57.8%) | 6.5% |
| Status | |||||||
| DVA | 140 (4.8%) | 3,002 (1.5%) | 3.3% | 653 (4.5%) | 0.3% | 585 (4.0%) | 0.8% |
| None | 902 (30.9%) | 67 813 (33.5%) | −2.6% | 4551 (31.5%) | −0.6% | 5575 (38.2%) | −7.3% |
| Use paracetamol in | |||||||
| No | 1794 (61.5%) | 155382 (76.8%) | −15.3% | 9038 (62.5%) | −1% | 10369 (71.1%) | −9.6% |
| Last 2 weeks | |||||||
| Yes | 1122 (38.5%) | 46 850 (23.2%) | 15.3% | 5416 (37.5%) | 1% | 4211 (28.9%) | 9.6% |
| Psychological | |||||||
| Low | 2202 (78.2%) | 154867 (78.0%) | 0.2% | 10884 (78.0%) | 0.2% | 11391 (80.6%) | −2.4% |
| Distress | |||||||
| Moderate | 406 (14.4%) | 29 758 (15.0%) | −0.6% | 2068 (14.8%) | −0.4% | 1883 (13.3%) | 1.1% |
| High or very high | 209 (7.4%) | 14 010 (7.1%) | 0.3% | 1009 (7.2%) | 0.2% | 854 (6.0%) | 1.4% |
| BMI categories | |||||||
| Underweight (<18.5) | 17 (0.6%) | 2,499 (1.3%) | −0.7% | 74 (0.6%) | 0% | 235 (1.8%) | −1.2% |
| Healthy (18.5−<25) | 463 (17.5%) | 70 580 (37.5%) | −20% | 2368 (18.2%) | −0.7% | 5264 (39.3%) | −21.8% |
| Overweight (25−<30) | 1040 (39.4%) | 74 754 (39.7%) | −0.3% | 5239 (40.2%) | −0.8% | 5315 (39.6%) | −0.2% |
| Obese (30+) | 1119 (42.4%) | 40 334 (21.4%) | 21% | 5345 (41.0%) | 1.4% | 2595 (19.4%) | 23% |
| Physical activity | |||||||
| 0–3 sessions/week | 642 (22.0%) | 30 842 (15.3%) | 6.7% | 3231 (22.4%) | −0.4% | 2675 (18.3%) | 3.7% |
| Sessions | |||||||
| 4–9 sessions/week | 1053 (36.1%) | 70 002 (34.6%) | 1.5% | 5208 (36.0%) | 0.1% | 5127 (35.2%) | 0.9% |
| 10–17 sessions/week | 830 (28.5%) | 63 373 (31.3%) | −2.8% | 3967 (27.4%) | 1.1% | 4451 (30.5%) | −2% |
| 18+ sessions/week | 391 (13.4%) | 38 015 (18.8%) | −5.4% | 2048 (14.2%) | −0.8% | 2327 (16.0%) | −2.6% |
| Broken bone in last | |||||||
| No | 2457 (86.6%) | 175655 (88.7%) | −2.1% | 12120 (86.4%) | 0.2% | 12132 (86.1%) | 0.5% |
| Year | |||||||
| Yes | 381 (13.4%) | 22,299 (11.3%) | 2.1% | 1905 (13.6%) | −0.2% | 1962 (13.9%) | −0.5% |
| Falls in last 12 | |||||||
| 0 | 1932 (68.8%) | 163172 (83.4%) | −14.6% | 9658 (69.4%) | −0.6% | 10765 (76.6%) | −7.8% |
| Months | |||||||
| 1 or more | 875 (31.2%) | 32 581 (16.6%) | 14.6% | 4264 (30.6%) | 0.6% | 3291 (23.4%) | 7.8% |
| Total | 2916 | 202232 | 14580 | 14580 | |||
BMI, body mass index; TKA, total knee arthroplasty.