Risk factors for development of systemic lupus erythematosus among J apanese females: medical history and reproductive factors

Aim The aim of the present study was to examine the influence of medical history and reproductive factors on the development of systemic lupus erythematosus ( SLE ) among J apanese females. Methods One hundred and sixty female SLE patients and 660 female volunteers were studied in a case–control study. Unconditional logistic regression was used to compute odds ratios ( OR ) and 95% confidence intervals ( CI s). Results The present study demonstrated that medical histories of operations without blood transfusion ( OR  = 1.64, 95% CI  = 1.10–2.44) and operations with blood transfusion ( OR  = 4.44, 95% CI  = 1.93–10.23) increased the risk of SLE with adjustment for age, region, smoking and alcohol drinking. Among 91 SLE patients and 284 control subjects who had the experience of married life, nulliparity ( OR  = 2.29, 95% CI  = 1.05–5.17), increased the risk of SLE , while the risk decreased according to the number of children (one to two vs . none, OR  = 0.27, 95% CI  = 0.10–0.73; three or more vs . none, OR  = 0.14, 95% CI  = 0.04–0.51; P for trend < 0.01). Conclusions Several factors are suggested to be associated with the development of SLE among J apanese females.