The causal relationship between uveitis and psoriatic arthritis: A bidirectional Mendelian randomisation study

Background Several traditional observational studies have reported an association between uveitis and psoriatic arthritis (PsA). However, the causal relationship between them remains unclear. Objective To investigate whether genetically predicted uveitis is related to the risk of PsA, and vice versa. Methods A two-sample bidirectional Mendelian randomisation (MR) design was employed, conducting a meta-analysis on data sourced from three distinct origins, followed by sensitivity analyses to ensure the robustness of the findings. Results MR analysis revealed a positive causal effect of uveitis on PsA. Meta-analysis results from three data sources revealed an odds ratio (OR) of 1.63, with a 95% confidence interval (CI) ranging from 1.22 to 2.19, and a statistically significant P-value of 0.001. Inverse MR results indicated a positive causal relationship between PsA and uveitis. Meta-analysis results: OR = 1.55, 95%CI = 1.07-2.24, P-value = 0.02. Limitations This study exclusively included individuals of European ancestry, thereby potentially limiting its generalisability to other populations, such as those of Asian or African descent. Secondly, Uveitis is a collective term for various intraocular inflammations, including anterior uveitis, intermediate uveitis, posterior uveitis, and pan uveitis. Conclusions The outcomes of our study indicate a significant association between uveitis and an elevated risk of PsA. Conversely, PsA is associated with an increased risk of uveitis. These findings add to the understanding of the complex relationship between uveitis and PsA, suggesting the possibility of mutual influence.