| Cases n (%) | Controls n (%) | OR 95% CI | ||
| Smoked at or before arthritis | 57 (58.8) | 102 (63.0) | 0.68 (0.39 to 1.17) | |
| Drank alcohol >35 units/week at or before arthritis onset | 13 (13.7) | 38 (23.8) | 0.57 (0.27 to 1.20) | |
| Surgery | 26 (27.4) | 43 (27.6) | 0.91 (0.51 to 1.64) | |
| Road traffic accident | 7 (7.3) | 10 (6.3) | 1.15 (0.41 to 3.19) | |
| Fracture | 6 (6.3) | 11 (7.95) | 1.0 (0.34 to 2.96) | |
| Any trauma | 39 (39.8) | 61 (37.9) | 1.10 (0.65 to 1.86) | |
| Trauma leading to medical care | 14 (14.9) | 12 (7.9) | 2.53 (1.1 to 6.0) |