Association of Serum Bilirubin and Lipid Ratio (Total Cholesterol/(High-Density Lipoprotein + Bilirubin)) in Coronary Artery Disease: A Case-Control Study at a Tertiary Care Hospital

Introduction: Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide, particularly in industrialized societies. The aim of the study was to investigate the potential association between lipid ratios and CAD risk and explore their diagnostic performance compared to traditional lipid profile parameters and total bilirubin levels. Methods: A total of 50 cases with CAD and 50 controls without CAD were recruited. Clinical data, including age, gender, comorbidities, blood pressure, glucose levels, smoking history, cardiovascular examination findings, and electrocardiogram (ECG) results, were collected. Lipid profile parameters (total cholesterol (TC), high-density lipoproteins (HDL), low-density lipoproteins (LDL), and triglycerides) and total bilirubin levels were measured. Lipid ratios, including cholesterol (CHO)/HDL, LDL/HDL, HDL + bilirubin, LDL/(HDL + bilirubin), and TC/(HDL + bilirubin), were calculated. Results: Significant differences were observed between cases and controls for comorbidities, including hypertension, diabetes, and obesity (p = 0.025), and ECG findings (p < 0.001). Lipid profile parameters were significantly different between cases and controls (p < 0.001). Lipid ratios also showed significant differences (p < 0.001) and demonstrated high sensitivity and specificity in identifying CAD. Among the ratios, LDL/HDL had the highest area under the curve (AUC) of 0.977, followed by CHO/HDL (AUC = 0.913), LDL/(HDL + bilirubin) (AUC = 0.903), and TC/(HDL + bilirubin) (AUC = 0.807). Total bilirubin alone did not show a significant association with CAD (AUC = 0.590, p = 0.119). Conclusion: Lipid ratios (CHO/HDL, LDL/HDL, HDL + bilirubin, LDL/(HDL + bilirubin), and TC/(HDL + bilirubin)) showed promising potential as predictors of CAD, outperforming traditional lipid profile parameters and total bilirubin levels. These ratios could serve as valuable diagnostic tools in identifying individuals at higher risk of CAD.