High level of gamma-glutamyltransferase is a possible risk factor for psoriasis: A nationwide population-based cohort study

Background: Gamma-glutamyl transferase (GGT) has been associated with coronary heart disease, diabetes mellitus, and hypertension, but its association with psoriasis has not yet been elucidated. Aims: We conducted this study to determine the association between the risk of psoriasis and the serum GGT. Methods: We conducted a nationwide population-based study. A total of 9,939,350 people met the enrolment criteria. The study population was classified into four groups based on GGT levels and the risk of psoriasis was calculated for each group. Results: The incidence rates of psoriasis per 1,000 person-years were 2.96105 and 3.68577 in the lowest and highest GGT groups, respectively. After adjusting for age, sex, income, diabetes mellitus, hypertension, dyslipidemia, smoking, alcohol intake, exercise, and body mass index, the highest GGT group showed a significantly increased risk of developing psoriasis (hazard ratio: 1.057, 95% confidence interval: 1.044-1.07). This risk of psoriasis was significantly higher among the old age group (hazard ratio: 1.162, 95% confidence interval: 1.128-1.197) and women (hazard ratio: 1.14, 95% confidence interval: 1.117-1.164). Limitations: The limitations of this study included the retrospective design, International Classification of Diseases code-based diagnosis, small hazard ratio, and non-availability of data on covariates. Conclusion: The GGT level was found to be an independent risk factor for developing psoriasis.