Association of total bilirubin and indirect bilirubin content with metabolic syndrome among Kazakhs in Xinjiang

Background Some studies have shown that a high level of bilirubin is a protective factor against metabolic syndrome (MS), while a high level of transaminase is a risk factor for MS. However, the existing results are inconsistent and few cohort studies have been published. Methods Using an ambispective cohort study, 565 Kazakhs from Xinjiang, China were selected as the study subjects. The baseline serum bilirubin and transaminase levels of the subjects were divided into quartiles and the relationship between these values and the incidence of MS was analyzed. The definition of MS was based on the Joint Interim Statement (JIS) diagnostic criteria. Results The average follow-up time for the subjects was 5.72 years. The cumulative incidence of MS was 36.11% (204 of the 565 subjects), and the incidence density was 63.10/1000 person-years. Multivariate Cox regression analysis showed that the levels of total bilirubin (TBIL) and indirect bilirubin (IBIL) were negatively correlated with the occurrence of MS, Compared to the lowest quartile level (Q1), the hazard ratios of MS the TBIL levels at the Q2-Q4 quartiles were: 0.47 (0.31-0.71), 0.53 (0.35-0.79), and 0.48 (0.32-0.72), respectively, while IBIL levels at the Q2-Q4 quartiles showed an MS hazard ratio of 0.48 (0.32-0.72), 0.54(0.36-0.81), and 0.52 (0.35-0.77), respectively, all at a 95% confidence level. However, no relationship was found between transaminase levels and the incidence of MS. Conclusion Serum TBIL and IBIL levels were negatively correlated with the incidence of MS in a Kazakh population in China.