Smoking and use of hair treatments in relation to risk of developing systemic lupus erythematosus

Objective. To examine the association between smoking and hair treatments ( dyes, permanents) and risk of developing systemic lupus erythematosus (SLE) . Methods. Patients (n = 265) diagnosed between January 1, 1995, and July 31, 1999, were recruited through 4 university based and 30 community based rhe umatology practices in eastern North Carolina and South Carolina. Controls (n = 355) were identified through driver's license records and were frequen cy matched to patients by age, sex, and state. Data collection included a 6 0 min in-person interview. Analyses were limited to experiences that occurr ed before age at diagnosis (patients) or reference age (controls). Because the prevalence of use of hair treatments among men was very low, the analys es of those exposures were limited to women. Results. There was no association with smoking history and risk of developi ng SLE when analyzed as status (current, former, or never-smoker) or measur es of dose (duration or pack-years). Use of permanent hair dyes in women wa s associated with a small increased risk of developing SLE (OR 1.5, 95% CI 1.0, 2.2). This association increased with longer duration of use (compared with nonusers, OR 1.7, 95% CI 1.0, 2.7 for 6 or more years). There was lit tle evidence of an association between SLE and use of temporary dyes or of permanents and straighteners. Conclusion. These results suggest at most a weak association between SLE ri sk and permanent hair dyes or smoking. Genetic variability in the metabolis m of these products may be important to assess in future studies.