Hypertension and frozen shoulder: A bidirectional 2-sample Mendelian randomization study

Observational studies have demonstrated an association between hypertension and frozen shoulder (FS). However, there is still a lack of clarity about their possible causal relationship. This study aimed to explore whether a genetic relationship exists between hypertension and FS bidirectional through 2-sample Mendelian randomization (MR) analysis. In this study, we investigated the following using data from genome-wide association studies. Exposure-related genetic variants that are independent of each other, were rigorously screened for use as instrumental variables (IVs). To investigate the causal connection, we performed the bidirectional 2-sample MR analysis using these IVs. Inverse-variance weighted (IVW) analysis was the primary method used to analyze the data and augmented by 4 additional analyses: MR-Egger, simple model, weighted model, and weighted median. Additionally, sensitivity analyses were performed to evaluate the impact of heterogeneity and pleiotropy on the results of our study, by comparing different models and tests to ensure robustness. The result of IVW analysis indicated a negative association between hypertension and FS (OR: 0.923, 95% confidence area (CI): 0.863-0.986, P-value was .018); Conversely, no significant effect of FS on developing hypertension cloud be observed (OR: 0.867, 95% CI: 0.746-1.008, P-value was .063). The stability of these results was verified through sensitivity analyses. Our research revealed a negative association between hypertension and FS; however, reverse MR analysis did not demonstrate a causal effect of FS on hypertension. There was no reciprocal genetic causation between these 2 conditions.