Relative risk of developing rheumatoid factor (RF) positive rheumatoid arthritis, RF negative rheumatoid arthritis, and rheumatoid arthritis overall for subjects in different occupational classes compared with higher non-manual employees, by sex
| RF+ RA | RF− RA | Total RA | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Ca/Co | RR | 95% CI | Ca/Co | RR | 95% CI | Ca/Co | RR | 95% CI | |
| †Reference group. | |||||||||
| Ca/Co, number of exposed cases/number of exposed controls; CI, confidence interval; RF, rheumatoid factor; RR, relative risk adjusted for age and residential area or for age, residential area, and sex (category “All”). | |||||||||
| Women | |||||||||
| Unskilled manual workers | 96/160 | 1.7 | 1.0 to 2.7 | 51/160 | 0.7 | 0.4 to 1.3 | 147/160 | 1.2 | 0.8 to 1.8 |
| Skilled manual workers | 36/71 | 1.7 | 0.9 to 3.2 | 23/71 | 1.0 | 0.5 to 2.0 | 59/71 | 1.3 | 0.8 to 2.2 |
| Assistant non-manual employees | 88/139 | 2.2 | 1.3 to 3.6 | 36/139 | 0.7 | 0.4 to 1.2 | 124/139 | 1.4 | 0.9 to 2.1 |
| Intermediate non-manual employees | 78/159 | 1.4 | 0.8 to 2.4 | 45/159 | 0.8 | 0.5 to 1.4 | 123/159 | 1.1 | 0.7 to 1.7 |
| Higher non-manual employees† | 35/99 | 1.0 | – | 34/99 | 1.0 | – | 69/99 | 1.0 | – |
| Men | |||||||||
| Unskilled manual workers | 34/55 | 1.3 | 0.6 to 2.5 | 11/55 | 0.9 | 0.4 to 2.2 | 45/55 | 1.1 | 0.6 to 2.0 |
| Skilled manual workers | 46/57 | 1.8 | 0.9 to 3.3 | 20/57 | 1.1 | 0.5 to 2.7 | 66/57 | 1.6 | 0.9 to 2.8 |
| Assistant non-manual employees | 13/32 | 0.6 | 0.2 to 1.5 | 11/32 | 1.7 | 0.7 to 4.6 | 24/32 | 1.0 | 0.5 to 2.0 |
| Intermediate non-manual employees | 27/63 | 1.1 | 0.6 to 2.2 | 11/63 | 0.8 | 0.3 to 2.0 | 38/63 | 1.0 | 0.6 to 1.8 |
| Higher non-manual employees† | 34/73 | 1.0 | – | 20/73 | 1.0 | – | 54/73 | 1.0 | – |
| All | |||||||||
| Unskilled manual workers | 130/215 | 1.5 | 1.0 to 2.3 | 62/215 | 0.7 | 0.5 to 1.2 | 192/215 | 1.2 | 0.8 to 1.6 |
| Skilled manual workers | 82/128 | 1.7 | 1.1 to 2.7 | 43/128 | 1.0 | 0.6 to 1.8 | 125/128 | 1.4 | 1.0 to 2.1 |
| Assistant non-manual employees | 101/171 | 1.6 | 1.0 to 2.5 | 47/171 | 0.9 | 0.5 to 1.4 | 148/171 | 1.3 | 0.9 to 1.8 |
| Intermediate non-manual employees | 105/222 | 1.3 | 0.8 to 1.9 | 56/222 | 0.8 | 0.5 to 1.3 | 161/222 | 1.1 | 0.8 to 1.5 |
| Higher non-manual employees† | 69/172 | 1.0 | – | 54/172 | 1.0 | – | 123/172 | 1.0 | – |