Risk factors for development of systemic lupus erythematosus among Japanese 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 Japanese 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 (CIs). 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 Japanese females.