Liver enzymes and risk of ocular motor cranial nerve palsy: a nationwide population-based study

This study aimed to assess the associations between liver enzymes including γ-glutamyl transferase (GGT) and the development of ocular motor cranial nerve palsy (CNP) using the National Sample Cohort database from Korea's National Health Insurance Service. We analyzed data from 4,233,273 medical screening examinees aged 20 years or more in 2009. Study participants were followed up until December 31, 2018. A Cox proportional hazard regression analysis was performed for quartiles of liver enzymes to determine the linkage between each value and ocular motor CNP using quartile 1 as a reference after adjusting for potential confounders. A total of 5,807 (0.14%) patients developed ocular motor CNP during the follow-up period of 8.22 ± 0.94 years. The incidence of ocular motor CNP gradually increased as the GGT levels increased. The highest quartile of the GGT group had hazard ratio (HR) of 1.245 (95% confidence interval [CI], 1.136-1.365). Regarding alanine aminotransferase (ALT), the highest quartile of the ALT group had HR of 1.141 (95% CI, 1.049-1.241). However, the incidence of ocular motor CNP did not gradually increase as the ALT levels increased. The coexistence of the increased level of GGT, metabolic syndrome, and obesity showed a stronger association with ocular motor CNP development (HR, 1.331; 95% CI, 1.173, 1.511) compared to having a single factor or two factors. In conclusion, our population-based cohort study demonstrated a significant association between serum GGT level and the incidence of ocular motor CNP, suggesting that GGT could be a new clinical marker for predicting the occurrence of ocular motor CNP.