Table 2.
Cohort description by pain group
| Low pain (OKS-PS > 14) | High pain (OKS-PS ≤ 14) | |
|---|---|---|
| Observations: n (%) | 107,542 (85.3%) | 18,522 (14.7%) |
| Gender: n (%) | ||
| Female | 57,771 (54%) | 10,343 (56%) |
| Male | 42,683 (40%) | 6623 (36%) |
| Not specified | 98 (0%) | 8 (0%) |
| Missing | 6990 (7%) | 1548 (8%) |
| Age band: n (%) | ||
| 40–49 years of age | 167 (0%) | 91 (0%) |
| 50–59 years of age | 8668 (8%) | 2712 (15%) |
| 60–69 years of age | 37,112 (35%) | 6471 (35%) |
| 70–79 years of age | 42,070 (39%) | 6003 (32%) |
| 80–89 years of age | 12,529 (12%) | 1697 (9%) |
| 90+ years of age | 6 (0%) | 0 (0%) |
| Missing | 6990 (7%) | 1548 (8%) |
| Pre-op OKS score1 | ||
| Mean (SD) | 19.8 (8) | 14.4 (8) |
| Median (IQR) | 20 (11) | 14 (10) |
| Missing | 1229 (1%) | 244 (1%) |
| Standardised pre-op OKS-Pain score 2 | ||
| Mean (SD) | 36.5 (16) | 25.6 (15) |
| Median (IQR) | 35.7 (21.42) | 25.0 (21.42) |
| Missing | 1227 (1%) | 243 (1%) |
| Standardised pre-op OKS-Function score 3 | ||
| Mean (SD) | 48.0 (18) | 36.4 (17) |
| Median (IQR) | 45 (25) | 35 (20) |
| Missing | 1185 (1%) | 240 (1%) |
| Pre-op EQ-5D index4 | ||
| Mean (SD) | 0.442 (0.30) | 0.249 (0.32) |
| Median (IQR) | 0.620 (0.532) | 0.159 (0.603) |
| Missing | 5887 (5%) | 1990 (11%) |
| Pre-op EQ-5D VAS5 “Your own health state today” | ||
| Mean (SD) | 69.6 (19) | 59.8 (22) |
| Median (IQR) | 74 (25) | 60 (35) |
| Missing | 10,807 (10%) | 2304 (12%) |
| “How would you describe the results of your operation?” n (%) | ||
| Excellent | 31,212 (29%) | 615 (3%) |
| Very good | 42,716 (40%) | 1756 (9%) |
| Good | 25,755 (24%) | 4915 (27%) |
| Fair | 6740 (6%) | 7273 (39%) |
| Poor | 602 (1%) | 3740 (20%) |
| Missing | 517 (0%) | 223 (1%) |
| “Overall, how are your problems now, compared to before your operation?” n (%) | ||
| Much better | 89,210 (83%) | 2954 (16%) |
| A little better | 14,271 (13%) | 6005 (32%) |
| About the same | 2286 (2%) | 3489 (19%) |
| A little worse | 1237 (1%) | 3227 (18%) |
| Much worse | 227 (0%) | 2647 (14%) |
| Missing | 331 (0%) | 150 (1%) |
| Post-op OKS scorea | ||
| Mean (SD) | 38.2 (7) | 17.8 (6) |
| Median (IQR) | 39 (11) | 19 (8) |
| Missing | 44 (0%) | 2 (0%) |
| Standardised post-op OKS-Pain scoreb | ||
| Mean (SD) | 82.4 (14) | 36.0 (12) |
| Median (IQR) | 85.7 (25.0) | 39.3 (17.9) |
| Missing | 0 (0%) | 0 (0%) |
| Standardised post-op OKS-Function scorec | ||
| Mean (SD) | 75.4 (8) | 38.8 (8) |
| Median (IQR) | 80 (25) | 40 (20) |
| Missing | 44 (0%) | 2 (0%) |
| Post-op EQ-5D indexd | ||
| Mean (SD) | 0.792 (0.19) | 0.395 (0.30) |
| Median (IQR) | 0.796 (0.309) | 0.516 (0.532) |
| Missing | 4934 (5%) | 1150 (6%) |
| Post-op EQ-5D VASe “Your own health state today” | ||
| Mean (SD) | 76.9 (16) | 55.1 (20) |
| Median (IQR) | 80 (20) | 55 (30) |
| Missing | 5413 (5%) | 1333 (7%) |
acaptures knee pain and function, scored from 0 to 48 where 0 indicates most and 48 least pain and functional limitations
bOKS Pain subscale as captured by seven questions, scored 0–100 where 0 indicates most and 100 least pain
cOKS Function subscale as captured by five questions, scored 0–100 where 0 indicates most and 100 least functional limitations
da health-related quality of life measure where 0 represents death and 1 refers to perfect health
ea Visual Analogue Scale ranging from 0 to 100, where 0 represents the worst and 100 the best imaginable health state