Causal relationship between asthma and chronic rhinosinusitis: A Mendelian randomization study

Observational studies have shown an association between asthma and chronic rhinosinusitis (CRS), but the exact causal relationship has not been clarified. This study aimed to deeply explore the causal relationship between asthma and CRS by using a 2-sample bidirectional Mendelian randomization (MR) method. This study used a 2-sample MR method, utilizing genome-wide association study data on asthma from the UKB database with a sample of 56,167 asthma patients and 3,52,255 controls, and CRS genome-wide association study data from the FinnGen database with a total of 8524 CRS patients and 1,67,849 controls. We conducted causal analyses through the inverse-variance weighting method, MR-Egger method, weighted median method, and weighted mode method, applied Cochrane's Q test for heterogeneity, and the MR-Egger intercept test for horizontal pleiotropy. At the same time, we implemented the MR-PRESSO and "leave-one-out" tests to verify the stability of the results. The analysis results showed a positive correlation between asthma and CRS, with an odds ratio of 1.320 (95% confidence interval = 1.206-1.444, P < .001). The results did not show heterogeneity or horizontal bias (P > .05), and the "leave-one-out" test also confirmed the reliability of this association. In the reverse MR analysis, no causal association was observed between CRS and asthma, with an odds ratio of 1.030 (95% confidence interval = 0.998-1.062, P = .065). Similarly, no horizontal bias or heterogeneity was found (P > .05), and the "leave-one-out" test also verified the reliability of this result. The results indicate that asthma may increase the risk of developing CRS, while CRS does not seem to increase the risk of developing asthma. This finding provides new insights into the complex causal relationship between the 2 and offers important evidence for the prevention and treatment of related diseases in the future.