Smoking, Alcohol Consumption, Physical Activity and Risk of Inflammatory Bowel Disease in Psoriasis: a Nationwide, Population-based Study

We aimed to assess the effect of health-related behaviors on the risk of developing inflammatory bowel disease (IBD) in patients with psoriasis. A nationwide, population-based cohort study was performed using the Korean National Healthcare Insurance database. A total of 4,586,524 individuals aged over 20 years undergoing national health screening in 2009 were enrolled. Individuals who developed Crohn's disease (CD) or ulcerative colitis (UC) were identified. The adjusted hazard ratio (aHR) was calculated to define the combined effect of psoriasis and health-related behaviors, including smoking, alcohol consumption, and physical activity on the development of IBD. Patients with psoriasis had a significantly higher risk of developing CD (aHR, 1.89; 95% confidence interval [CI], 1.22-2.91) and UC (aHR, 1.39; 95% CI, 1.11-1.74) compared to the general population. Former smokers with psoriasis had a 2.43-fold increased risk of developing UC compared to non-smokers without psoriasis (95% CI, 1.59-3.72). Current smokers with psoriasis had the highest risk of developing CD (aHR, 2.53; 95 CI, 1.25-5.14) compared to non-smokers without psoriasis. The preventive effects of alcohol consumption and regular physical activity on the development of IBD were diminished among patients with psoriasis. Smoking behaviors heightened the impact of psoriasis on the development of psoriasis. Conversely, psoriasis might attenuate the protective effects of alcohol consumption and physical activity on IBD risk.