SYSTEMIC LUPUS-ERYTHEMATOSUS - A CASE-CONTROL EPIDEMIOLOGIC-STUDY IN JAPAN

Background. Systemic lupus erythematosus (SLE) is designated by the Ja panese government as one of the intractable diseases and all patients, who suffer from these diseases, are registered to get financial aid f or treatment. Using newly registered SLE patients, a case-control stud y was conducted to evaluate potential risk factors. Methods. Two-hundr ed and eighty-two women SLE patients, newly registered to receive fina ncial aid for treatment, and 292 randomly selected health examination participants at public health centers (controls) were surveyed from Ap ril 1988 through March 1990. By means of a self-administered questionn aire, data concerning demographic variables, smoking and drinking habi ts, past medical and reproductive history, and family history were col lected. Results. Based on unconditional logistic regression analysis, the risk of SLE was significantly increased for current smokers (age-a djusted odds ratio (OR) = 2.31, 95% confidence interval (cl) 1.34-3.97 ). Alcohol and milk intake were inversely associated with risk. Family histories of asthma and collagen diseases, including SLE, were associ ated with significantly elevated risk of SLE (OR = 2.07, 95% CI 1.14-3 .77; OR = 5.20, 95% CI 1.0-24.95, respectively). Regarding reproductiv e function, women with menarche at age 15 or later had significantly h igher risk than those, who started menstruating before age 12 (OR = 3. 82, 95% CI 1.66-8.81 for menarche at > 15 years and OR = 2.90, 95% CI 1.14-7.39 for menarche at greater than or equal to 16y). Conclusions. Our study suggests several risk factors, including smoking, family his tory, and reproductive history that may increase the risk of SLE.