Associations of combined lifestyle and genetic risks with incident psoriasis: A prospective cohort study among UK Biobank participants of European ancestry

Background: Whether the lifestyle is associated with the risk of psoriasis in the presence of different genetic risk levels remains unknown. Objective: To examine the gene-behavior interaction in association with incident psoriasis. Methods: This study is based on the data from the UK Biobank, which recruited 500,000 participants. Genetic risk was categorized into low, intermediate, and high groups. The lifestyle score comprised the body mass index, smoking, physical activity, and diet and was also categorized into the ideal, intermediate, and poor groups. Within each genetic risk group, the risks of incident psoriasis associated with each lifestyle level were investigated and compared with the low genetic risk and ideal lifestyle group. Results: Compared with the low genetic risk and ideal lifestyle group, the poor lifestyle and high genetic risk group was associated with a hazard ratio of up to 4.625 (95% confidence interval [CI], 2.920-7.348) for psoriasis. There was no interaction between genetic risk and lifestyle. The population attributable fractions of lifestyle and genetic risk were 32.2% (95% CI, 25.1%-38.6%) and 13.0% (95% CI, 3.2%-21.8%), respectively. Limitations: No verification in other independently ascertained populations. Conclusion: Lifestyle factors are predictive of the risk of incident psoriasis independent of genetic risk, and the relative impact of lifestyle factors was greater than that of genetic risk.