Risk Factors for Lichen Sclerosus: A Case-Control Study of 43,000 Finnish Women.

OBJECTIVES:Lichen sclerosus (LS) is an inflammatory skin disease probably arising from an interplay of genetics, local irritation, and autoimmune processes. We identified potential risk factors for the disease using data from nationwide Finnish registries. METHODS:We identified all women diagnosed with LS within specialized health care during 1998-2016 (n = 10,692) and selected 3 age-matched population control women for each case. We calculated odds ratios (ORs) for possible risk factors using conditional logistic regression. RESULTS:Dermatological autoimmune conditions were strongly associated with LS (OR = 15.1, 95% confidence interval [CI] = 13.6-16.7 for morphea; OR = 10.3, 95% CI = 5.02-19.0 for lichen planus; OR = 6.86, 95% CI = 5.65-8.33 for alopecia; OR = 2.20, 95% CI = 1.88-2.56 for vitiligo). A diagnosis of Crohn or celiac disease increased the odds of LS (OR = 1.80, 95% CI = 1.71-1.89; OR = 1.49, 95% CI = 1.28-1.73, respectively) as did urge and stress incontinence (OR = 1.79, 95% CI = 1.71-1.87; OR = 1.28, 95% CI = 1.22-1.35, respectively).The odds of LS were lower in women after a diagnosis of type 1 diabetes (OR = 0.43, 95% CI = 0.41-0.45), coronary artery disease (OR = 0.41, 95% CI = 0.38-0.43), and rheumatoid arthritis (OR = 0.38, 95% CI = 0.36-0.41).Parous women had higher odds of LS (OR = 1.11, 95% CI = 1.04-1.17) than nulliparous ones, but increasing number of births decreased the risk. Lichen sclerosus was not associated with socioeconomic status nor the urbanicity level of the place of residence. CONCLUSIONS:Certain autoimmune diseases and urinary incontinence were associated with LS.