Smoking is a Risk Factor for Autoimmune Hepatitis: An English Registry-Based Case-Control Study

Smoking is a risk factor for some autoimmune diseases, but its association with autoimmune hepatitis remains unknown. We conducted a population-based matched case-control study to examine the association between tobacco smoking and the risk of autoimmune hepatitis in England.

From the Clinical Practice Research Datalink and linked Hospital Episode Statistics, 2005-2017, we included 987 cases diagnosed with autoimmune hepatitis after age 18 years and up to 10 frequency-matched population controls per case. We used multiple logistic regression to estimate the odds ratio of autoimmune hepatitis in ever-smokers vs never-smokers, adjusting for sex, age, general practice, calendar time of registration with the general practice, and socioeconomic status.

The autoimmune hepatitis cases were more likely to be ever-smokers than the controls (44% vs 37%). The ever-smokers had an increased risk of autoimmune hepatitis compared with the never-smokers (adjusted odds ratio = 1.20, 95% confidence interval 1.03-1.39).

Smoking was associated with an increased risk of autoimmune hepatitis.