Objective-To investigate the eVect of smoking on the development of systemic lupus erythematosus (SLE), and the association between alcohol consumption and the disease. Methods-450 subjects (150 SLE patients and 300 controls) from Nottingham, UK were interviewed in a case-control study. Controls were matched to cases for age and sex. All patients met at least four of the American Rheumatology Association criteria for SLE. Controls were randomly selected from the Nottingham Family Health Services Authority register. Information was collected by interview administered questionnaire concerning demographic variables, smoking histories, and drinking habits. Results-Analysis of the data by conditional logistic regression revealed current smokers to have a significantly increased risk of development of SLE compared with never smokers (odds ratio (OR) 1.95, 95% confidence intervals (CI) 1.14, 3.31), although ex-smokers were not at increased risk. There was also suggestion of a marked, highly significant negative association between SLE and alcohol consumption, the magnitude of which increased with units consumed. Conclusions-This study suggests that current smokers are at increased risk of developing SLE compared with nonsmokers and ex-smokers. In contrast, alcohol consumption seems to be negatively associated with the disease. (Ann Rheum Dis 1998;57:451-455) Although certain genetic factors and sex hormones are known to influence the development of systemic lupus erythematosus (SLE), environmental factors may be paramount.

We confirm that lupus women who have, or later develop, SLE are at greater risk of pregnancy loss by spontaneous or surgical means. We have also shown that race, and the inherent differences in social and cultural influences, appears to be an important determinant of ultimate family size; White women with SLE have fewer children than controls, whilst non-White lupus women tend to have larger families.

Of the variables studied, the UPA(8) score was the strongest predictor of variations in referral rates. This association is most likely to be through a link with morbidity, although it could reflect differences in patients' perceptions, doctors' behaviour, or the use and provision of services.

Hair treatment or duration of hair treatment usage is not significant in the aetiology of SLE. Although patients with SLE were less likely in this study to have highlights than controls, for all other hair treatments no differences were observed.