A total of 481,414 Korean participants aged 40-79 years at enrollment were examined. The hazard ratios for all-cause, all-cancer, and head and neck cancer mortality were analyzed using Cox proportional hazards models, which were adjusted for potential confounding factors. In the overall study population, the highest AST/ALT ratio level was significantly associated with risk of all-cause, all-cancer, and head and neck cancer mortality (p < 0.01). After excluding participants who died of all-cause, all-cancer, and head and neck cancer within five years of enrollment, the main results remained similar to those of the analysis of all deaths in the study population. These findings indicate that serum AST/ALT ratio is positively associated with an increased mortality risk in all-cause, all-cancer, and head and neck cancer.

Background: The purpose of this study was to determine the bidirectional association between burning mouth syndrome (BMS) and depression disorders. Methods: A total of 854 pairs of BMS and 58 999 pairs of depression disorders matched 1:1 for age and sex were analyzed using conditional logistic regression models, which were adjusted for potential confounding factors. Results: Bidirectional analysis found that BMS was associated with depression disorders (odds ratio=4.64, P < 0.001) and depression disorders was also significantly associated with BMS (odds ratio=2.97, P < 0.001). Conclusion: These findings indicate a significant bidirectional association between BMS and depression disorders. The odds ratios suggest that BMS is a stronger predictor for incidence of depression disorders than depression disorders predicting incidence of BMS. Given this retrospective cohort design, the mechanisms underlying the association between BMS and depression disorders are not directly analyzed. Therefore, further investigation are needed to analyze the causality between BMS and depression disorders.