Forget LDL and HDL Cholesterol – Welcome the Apolipoproteins

After all these years learning the difference between the ‘good’ cholesterol (HDL-C or high-density lipoprotein cholesterol) and the ‘bad’ (LDL-C or low-density lipoprotein cholesterol), we can now turn our attention to two apolipoproteins – A1 and B. These apolipoproteins bind to fats, producing lipoproteins, and are the major constituents of LDL and HDL cholesterol, respectively.

In an international study reported in the journal Lancet, some 12,500 patients with an acute heart attack were compared with 15,000 age- and sex-matched controls to assess the usefulness of different of various cardiovascular risk factors. Non-fasting cholesterol fractions and apolipoproteins were measured, in order to determine their predictive values.

Ratios – such as the LDL-C/HDL-C ratio - were stronger predictors of heart attack than either of the individual components, and apolipoproteins were better predictors than the cholesterols (total, LDL, or HDL). The Apo-B/Apo-A1 ratio was the strongest predictor, with a population-attributable risk of 54%, compared with risks of 37% for LDL/HDL and 32% for total cholesterol/HDL. ( The ‘population attributable risk’ is a term used in epidemiology – here it means the percent of the frequency of heart attack in the population that is associated with a particular risk factor.) The results were similar for both sexes, all ethnic groups, and all age groups.

Other studies have shown that the apolipoproteins yield better results in predicting heart attacks than the cholesterol levels can. The consistent results from this very large, international sample should help to settle any remaining controversies. It won’t be long before Apo-B and Apo-A1 are used in clinical practice worldwide for cardiovascular risk assessment.

Do you sometimes have the feeling that doctors ‘discover’ new tests, diagnoses, and syndromes, just to keep a jump ahead of their patients with respect to medical jargon? Apolipoproteins present an apparent example – but in this case, the ‘discovery’ represents a true step forward towards better medical care. The American Diabetes Association and the American College of Cardiology have recently made recommendations in favor of the use of apolipoprotein levels to monitor response to statin therapy in patients at high risk for diabetes, cardiovascular disease, or both.