Relationship between bilirubin, apolipoprotein B, and coronary artery disease.

Lipoprotein lipids and apo B from 254 male patients were compared with bilirubin as a risk factor for coronary artery disease (CAD). Patients were classified as: 1, Normal, all vessels < 20% stenosis, n = 83; or 2, CAD, at least one vessel > 70%, n = 171. Diagnostic accuracy was assessed by receiver operator characteristic curves (ROC). Corrections were made for possible confounding variables in the multivariate analysis. Upon ROC analysis, bilirubin showed an inverse relationship with risk of CAD, with areas under the ROC curve comparable to lipoprotein: however, bilirubin showed no discrimination below false positive frequencies of approximately 0.3. Logistic regression indicated that bilirubin was a weaker global marker than the lipoproteins and interacted with apo B. A highly significant correlation was found between bilirubin and apo B (p = 0.0025), but not with cholesterol, triglycerides, or high density lipoprotein cholesterol. Compared to lipoprotein markers, bilirubin provides little practical power of discrimination for CAD. Further studies of the affect of bilirubin on CAD must take its interaction with apo B into consideration.