Causality between ankylosing spondylitis and urolithiasis in European Populations: A Mendelian randomization analysis

Ankylosing spondylitis (AS) is an inflammatory condition affecting the spine. Observational studies have suggested a heightened risk of urolithiasis in AS patients. However, due to the inherent limitations of observational research, the causal relationship between the two remains to be determined.

Utilizing the Mendelian randomization analysis approach, this study sought to explore the causal link between AS and urolithiasis.

Data from genome-wide association studies were employed for analysis. Mendelian randomization analyses were conducted using the IVW, MR-Egger, Weighted Median, and Weighted Mode methods. Heterogeneity tests, sensitivity analyses, and pleiotropy analyses were also performed.

The causality between AS and urolithiasis was supported by the IVW (P=.02), Weighted Median (P=.006), and Weighted Mode (P=.01) methods. The MR-Egger method (P=.07) did not support this causal relationship, yet its directionality was consistent with the other three methods. None of the four analysis methods supported a reverse causal relationship between AS and urolithiasis.

Our study demonstrates a causal relationship between AS and urolithiasis, with no evidence of reverse causality. Given the increased risk of urolithiasis in AS patients, it is crucial to implement preventive strategies and early detection. Stone composition analysis should also be incorporated into clinical practice for these patients, as it can provide essential insights into the metabolic and genetic factors contributing to stone formation, thus improving diagnostic accuracy and treatment outcomes. Future studies are needed to further validate these findings and explore the detailed mechanisms involved.