Association between Sjögren syndrome and osteoporosis: A bidirectional Mendelian randomization study

This Mendelian randomization (MR) study aimed to investigate the relationships between Sjögren syndrome (SS) and osteoporosis (OP). We selected genetic instruments for predisposition to SS on published genome-wide association studies. Using a two-sample MR approach, we assessed association SS and OP. The random effects inverse variance weighting method was used as the primary analysis method, and the weighted median method, MR-Egger, weighted mode, and simple mode were used as supplementary analytical methods. Sensitivity analysis was performed using the heterogeneity test, the pleiotropy test, and the leave-one-out test. SS was notably associated with the presence of OP (odds ratio: 1.191; 95% confidence interval: 1.084-1.309; P < .005), but OP was not a susceptible factor for SS. This study suggested that from a genetic point of view, the SS was indeed a risk factor for OP. Furthermore, no significant causal effect of OP on SS was observed, indicating the absence of reverse causality between SS and OP.