Effect of Low Serum Total Bilirubin Levels (≤0.32 mg/dl) on Risk of Coronary Artery Disease in Patients With Metabolic Syndrome

The objective of this study was to investigate the effects of low serum bilirubin levels on the risk for future coronary artery disease (CAD) in a prospective cohort. CAD events were examined according to baseline serum bilirubin levels in a prospective large-scale, community-based Korean cohort in 2 subsequent prospective biennial surveys. A total of 8,593 subjects were included, 0.9% of whom reported newly developed CAD events during the 4 years of follow-up. Cox regression analyses showed that the lowest serum total bilirubin level category (bilirubin ≤0.32 mg/dl) was an independent risk factor for future CAD events (adjusted hazard ratio [HR] 1.890, 95% confidence interval [CI] 1.088 to 3.284; p = 0.024). Subjects with metabolic syndrome had a higher risk for future CAD events than those without metabolic syndrome (HR 3.366, 95% CI 2.079 to 5.448, p <0.001). Low bilirubin levels increased the CAD risk in subjects with metabolic syndrome further (HR 2.016, 95% CI 1.069 to 3.800; p = 0.030), with these subjects showing a >6 times higher risk for CAD than subjects with bilirubin levels >0.32 mg/dl and no metabolic syndrome (HR 6.228, 95% CI 3.118 to 12.437; p <0.001). In conclusion, the addition of low serum bilirubin levels to the traditional risk factors for CAD, such as metabolic syndrome, may yield an improvement of risk prediction.