Serum Apo A-1 and Its Role as a Biomarker of Coronary Artery Disease

OBJECTIVES: To evaluate the role of apolipoprotein(Apo A-1) as a biomarker of coronary artery disease (CAD) and its comparison with the traditional marker high-density lipoprotein (HDL). METHODOLOGY: One hundred patients proven to have coronary artery disease by angiography were recruited and their serum biomarkers were compared with 100 normal individuals adjusted for age and sex. RESULT: The mean +/-standard deviation (SD) value of plasma Apo A-1 levels in the normal individuals were observed to be 207.42 +/- 41.35 (mg/dL) against 90.69 +/- 20.77 (mg/dL) in the cardiac patients. On the other hand the serum HDL levels were 52.93 +/-33.58 (mg/dL) in the normal individuals and 37.86 +/- 23.19 (mg/dL) in the cardiac patients. Both of these differences were statistically significant (p < 0.001). For Apo A-1, a large proportion of patients (85%) were found to be in the abnormal range when compared to the control group in which only 7% had an abnormal value. For HDL, a majority (70%) of the cardiac patients had abnormal values while 40% of the normal individuals also had abnormal values. The sensitivity of Apo A-1 for detecting CAD was 85%, while for HDL, it was only 69%. Similarly, the specificity of Apo A-1 for detecting CAD was 93%, while for HDL, it was 60%. When plotted on a receiver operating characteristic (ROC) curve, Apo A-1 had a much larger area under the curve when compared to HDL. CONCLUSION: This study suggests that Apo A-1 may, in fact, be more sensitive than HDL as a predictor of CAD. However, to completely elucidate its role as a biomarker, to set target serum levels and to increase its clinical use, further studies are required.