The genetic evidence linking instant coffee and carpal tunnel syndrome: A Mendelian randomization study

The causal relationship between instant coffee consumption and carpal tunnel syndrome (CTS) remains unclear. This study aimed to investigate the potential causal association between instant coffee consumption and CTS using data from large-scale genome-wide association studies, thereby providing genetic epidemiological evidence on this association. This study selected single nucleotide polymorphisms strongly associated with instant coffee consumption as instrumental variables. A 2-sample Mendelian randomization (MR) design was used. Three MR analysis methods were used: inverse variance weighted, MR-Egger regression, and weighted median to assess potential causal relationships. Cochran’s Q test was used to evaluate heterogeneity in the data. Summary statistics were derived from 1,80,764 individuals for instant coffee consumption and 4,80,201 individuals for CTS, all of European ancestry, to minimize bias from population stratification. Sensitivity analyses were performed using the leave-one-out method to validate the robustness of the results. The inverse variance weighted results showed that the odds ratio of CTS with respect to instant coffee consumption was 3.41 (95% confidence interval: 1.65–7.04, P = .0009), suggesting a significant positive causal relationship between instant coffee consumption and CTS. Sensitivity analyses did not reveal significant heterogeneity and horizontal pleiotropy ( P > .05). This study suggested a potential positive causal association between instant coffee consumption and CTS using the 2-sample MR approach, although the findings should be considered preliminary and hypothesis-generating.