Assessing the causal relationship between obesity and ankylosing spondylitis: A two-sample Mendelian randomization study

This study aims to explore the potential causal relationship between obesity and ankylosing spondylitis (AS) using the Mendelian randomization (MR) approach. Data were derived from a comprehensive genome-wide association study dataset. Genetic loci that demonstrated significant, independent associations with both obesity and AS in populations of European ancestry were selected as instrumental variables. Multiple MR analyses, including MR-Egger, weighted median, and inverse variance weighting, were employed to assess the causal impact of obesity on AS risk. To ensure reliability, heterogeneity, and multiplicity tests were conducted, and the robustness of the findings was evaluated through sensitivity analyses using the "leave-one-out" method. The inverse variance weighting analysis revealed an odds ratio (OR) of 0.95 with a 95% confidence interval of 0.76 to 1.19 and a P value of .653. These results indicated no significant causal link between obesity and AS development. Additionally, the heterogeneity and multiplicity tests showed no significant findings, while sensitivity analyses reinforced the consistency and robustness of the conclusions. This research did not find evidence of a causal relationship between obesity and the development of AS based on two-sample MR analysis and genetic data evaluation. However, the current study's limitations, including sample size and study design, highlight the need for future research with larger cohorts to further explore the intricate relationship between obesity and AS.