Table 4

 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

Ca/CoRR95% CICa/CoRR95% CICa/CoRR95% 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”).
Unskilled manual workers96/1601.71.0 to 2.751/1600.70.4 to 1.3147/1601.20.8 to 1.8
Skilled manual workers36/711.70.9 to 3.223/711.00.5 to 2.059/711.30.8 to 2.2
Assistant non-manual employees88/1392.21.3 to 3.636/1390.70.4 to 1.2124/1391.40.9 to 2.1
Intermediate non-manual employees78/1591.40.8 to 2.445/1590.80.5 to 1.4123/1591.10.7 to 1.7
Higher non-manual employees†35/991.034/991.069/991.0
Unskilled manual workers34/551.30.6 to 2.511/550.90.4 to 2.245/551.10.6 to 2.0
Skilled manual workers46/571.80.9 to 3.320/571.10.5 to 2.766/571.60.9 to 2.8
Assistant non-manual employees13/320.60.2 to 1.511/321.70.7 to 4.624/321.00.5 to 2.0
Intermediate non-manual employees27/631.10.6 to 2.211/630.80.3 to 2.038/631.00.6 to 1.8
Higher non-manual employees†34/731.020/731.054/731.0
Unskilled manual workers130/2151.51.0 to 2.362/2150.70.5 to 1.2192/2151.20.8 to 1.6
Skilled manual workers82/1281.71.1 to 2.743/1281.00.6 to 1.8125/1281.41.0 to 2.1
Assistant non-manual employees101/1711.61.0 to 2.547/1710.90.5 to 1.4148/1711.30.9 to 1.8
Intermediate non-manual employees105/2221.30.8 to 1.956/2220.80.5 to 1.3161/2221.10.8 to 1.5
Higher non-manual employees†69/1721.054/1721.0123/1721.0