Assessing the causal relationship between psoriasis vulgaris and urolithiasis: A two-sample Mendelian randomization study

Psoriasis has been suggested to be associated with urolithiasis. However, the existing literature is based on observational studies, which provide limited evidence for the causal relationship between these two conditions. This research aims to evaluate the causal association between psoriasis vulgaris and urolithiasis using 2-sample Mendelian Randomization (MR) analysis. Exposures and outcomes were sourced from genome-wide association study data. The psoriasis vulgaris dataset included 5072 patients and 4,78,102 controls. The urolithiasis dataset included 5347 patients and 2,13,445 controls. We used the inverse-variance weighted (IVW) method as our primary analytical strategy, augmented by MR-Egger regression and the weighted median method. Cochran Q test, MR-Egger regression, leave-one-out analysis and Steiger filtering were also conducted to evaluated the stability and credibility of the results. The IVW analysis showed a significant association between psoriasis vulgaris and urolithiasis (odds ratio [OR] = 1.073, 95% confidence interval [CI] = 1.017-1.131, P = .010). The results of weighted median analysis (OR = 1.071, 95% CI = 1.013-1.133, P = .017) and MR-Egger regression (OR = 1.072, 95% CI = 0.992-1.158, P = .12) indicated a consistent directional causality with the IVW analysis. There was no significant horizontal pleiotropy or heterogeneity in the analysis. Steiger filtering further confirmed the accuracy of the directional causality. In conclusion, this MR study supports a causal association between psoriasis vulgaris and urolithiasis.