Swedish researchers surveyed over 400 patients with rheumatoid arthritis who had been treated at a University Hospital clinic between 1980 and 1995. Over 800 randomly selected healthy people were also surveyed. The questionnaires included requests for information on lifestyle factors, reproductive history, illness, stress, and exposure to a range of potential allergens.
Just over two thirds of the patients and 59 per cent of the healthy people responded. The results showed that women who had insulin-dependent diabetes were 10 times more likely to have the disease, and those who started their periods late and entered menopause early were over twice as likely to have rheumatoid arthritis. Prolonged use of hair dyes also doubled the risk.
Being an ex or current smoker significantly increased the risk of developing rheumatoid arthritis for both sexes. And in men this rose according to the number of cigarettes smoked every day, with those smoking more than a pack a day almost three times as likely to have the disease.
A history of allergies did not increase risk; if anything, it seemed to do the opposite. But men who had been repeatedly exposed to mould in their homes were over four times as likely to have the disease, while those living or working with farm animals were over three times as likely to be affected.
[Comorbidity and lifestyle, reproductive factors, and environmental exposures associated with rheumatoid arthritis 2001; 60: 934-9]
Annals of the Rheumatic Diseases