A case control study of female systemic lupus erythematosus in Japan

In a multi-institutional case-control study, we investigated risk factors for systemic lupus erythematosus (SLE) in 151 Japanese women treated for SLE during the period September 1988 to August 1990. We used two control groups: sisters of SLE patients and sisters of female patients with another disease. Information was obtained by a self-administered questionnaire. Our findings suggest that having a history of operations and blood transfusions and working in a cold environment may be risk factors for SLE. Viral infections, psychological stress, and pet ownership were not risk factors for SLE in our study. In addition, smoking was not protective for SLE. Skin sensitivity to sunlight and cold feet, which may be symptoms of SLE that occurred before the diagnosis, were also positively associated with SLE.