Sample characteristics (per cent) of osteoarthritis (OA) and non-OA individuals by exposure status
| Characteristics | OA cases (n=40817) | 1:1 matched non-OA (n=40817) | 1:3 matched non-OA (n=109450) |
|---|---|---|---|
| Age | |||
| 20–39 | 4.6 | 4.5 | 5.1 |
| 40–49 | 9.1 | 9.0 | 10.1 |
| 50–59 | 19.4 | 19.6 | 21.8 |
| 60–69 | 25.4 | 25.3 | 26.3 |
| 70–79 | 24.7 | 25.0 | 22.0 |
| ≥80 | 16.9 | 16.6 | 14.8 |
| Women | 71.6 | 71.6 | 68.2 |
| Body mass index | |||
| <18.4 | 1.7 | 1.9 | 1.8 |
| 18.5–24.9 | 30.7 | 35.9 | 36.4 |
| 25–29.9 | 30.5 | 29.7 | 30.8 |
| ≥30 | 20.5 | 14.3 | 14.6 |
| Missing | 16.6 | 18.2 | 16.4 |
| COPD | 3.0 | 2.0 | 2.0 |
| Diabetes | 11.5 | 9.9 | 9.4 |
| Hypertension | 37.6 | 32.1 | 30.4 |
| Physical activity | |||
| Active | 16.9 | 18.6 | 19.0 |
| Moderately active | 22.4 | 22.9 | 23.3 |
| Inactive | 60.6 | 58.5 | 57.7 |
| Pain medication use | 12.9 | 10.5 | 10.5 |
| Smoking | |||
| Currently smoke | 19.7 | 19.0 | 19.8 |
| Former smoker | 49.6 | 46.6 | 47.2 |
| Non-smoker | 30.7 | 34.4 | 33.0 |
| Fruits and vegetables | |||
| 0–3 serving daily | 16.1 | 15.6 | 15.3 |
| 4–6 serving daily | 43.1 | 43.7 | 43.6 |
| 6+ serving daily | 23.7 | 22.3 | 22.6 |
| Not stated | 17.1 | 18.5 | 18.5 |
| Income | |||
| <29999 | 32.4 | 29.1 | 27.4 |
| 30000–49999 | 21.7 | 20.6 | 20.6 |
| 50000–79999 | 17.1 | 16.9 | 17.7 |
| ≥80000 | 11.8 | 13.3 | 14.4 |
| Not stated | 17.0 | 20.2 | 19.9 |
| Education | |||
| Less than secondary | 35.4 | 36.4 | 34.6 |
| Secondary graduate | 15.4 | 15.9 | 16.2 |
| Some postsecondary | 6.1 | 5.3 | 5.5 |
| Postsecondary graduation | 41.4 | 40.0 | 41.3 |
| Not stated | 1.8 | 2.4 | 2.4 |
The distribution of all variables listed was significantly different between OA and non-OA subjects (p<0.01). COPD stands for chronic obstructive pulmonary disease.