Baseline characteristics of the study population
| Baseline characteristics | Total (n=697) | Subgroup 1 (n=330) ‘good outcome’ | Subgroup 2 (n=257) ‘moderate outcome’ | Subgroup 3 (n=110) ‘poor outcome’ |
|---|---|---|---|---|
| Demographics | ||||
| Age (years) | 56.0±5.1 | 56.2±5.2 | 55.8±5.2 | 55.6±4.8 |
| Female, no. (%) | 567 (81.3) | 262 (79.4) | 213 (82.9) | 92 (83.6) |
| Body mass index (kg/m2) | 26.6±4.3 | 25.5±3.6 | 27.4±4.4 | 28.0±4.9 |
| Clinical signs and symptoms | ||||
| NRS for knee pain (range 0–10) | 3.7±2.1 | 2.9±1.9 | 4.0±1.8 | 5.4±1.8 |
| Bilateral knee pain, no. (%) | 399 (57.2) | 184 (55.8) | 141 (54.9) | 74 (67.3) |
| Clinical knee OA, no. (%) | 606 (86.9) | 279 (84.5) | 223 (86.8) | 104 (94.5) |
| Morning stiffness knee, no. (%) | 497 (71.3) | 218 (66.1) | 187 (72.8) | 92 (83.6) |
| Bony tenderness, no. (%) | 365 (52.4) | 145 (43.9) | 146 (56.8) | 74 (67.3) |
| Crepitus, no. (%) | 367 (52.7) | 178 (53.9) | 126 (49.0) | 63 (57.3) |
| Active knee flexion range (degrees) | 133.3±10.0 | 135.2±9.0 | 132.4±9.7 | 130.0±12.3 |
| Total knee replacement after 5-year follow-up, no. (%) | 12 (1.7) | 2 (0.6) | 5 (1.9) | 5 (4.5) |
| Hip pain, no. (%) | 348 (49.9) | 133 (40.3) | 144 (56.0) | 71 (64.5) |
| Total hip replacement after 5-year follow-up, no. (%) | 10 (1.4) | 1 (0.3) | 4 (1.6) | 5 (4.5) |
| Radiographic features | ||||
| KL grade=0, no. (%) | 295 (42.3) | 155 (47.0) | 94 (36.6) | 46 (41.8) |
| KL grade=1, no. (%) | 321 (46.1) | 150 (45.5) | 117 (45.5) | 54 (49.1) |
| Osteophytosis, no. (%) | 122 (17.5) | 51 (15.5) | 44 (17.1) | 27 (24.5) |
| Joint space narrowing, no. (%) | 107 (15.4) | 40 (12.1) | 42 (16.3) | 25 (22.7) |
| Comorbidity count, no. (%) | ||||
| 0 | 166 (23.8) | 100 (30.3) | 52 (20.2) | 14 (12.7) |
| 1 | 205 (29.4) | 107 (32.4) | 73 (28.4) | 25 (22.7) |
| 2 | 151 (21.7) | 76 (23.0) | 57 (22.2) | 18 (16.4) |
| ≥ 3 | 162 (23.2) | 44 (13.3) | 70 (27.2) | 48 (43.6) |
| WOMAC data | ||||
| WOMAC pain (range 0–20) | 5.3±3.4 | 3.5±2.7 | 6.0±2.7 | 9.0±2.9 |
| WOMAC stiffness (range 0–8) | 2.8±1.6 | 2.1±1.4 | 3.1±1.4 | 4.4±1.5 |
| WOMAC function (range 0–68) | 16.8±11.6 | 9.8±7.4 | 19.5±8.5 | 32.7±10.2 |
| Psychological factors | ||||
| SF-36 vitality (range 0–100) | 63.4±16.8 | 68.5±14.5 | 61.6±16.5 | 51.9±17.3 |
| PCI resting (range 5–20) | 9.3±2.5 | 8.7±2.4 | 9.4±2.4 | 10.9±2.7 |
Values are presented as mean±SD unless otherwise indicated.
KL grade, Kellgren and Lawrence grade; NRS, numeric rating scale; OA, osteoarthritis; PCI, Pain Coping Inventory; SF-36, Short-Form 36 Health Survey; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.