ApoB versus non-HDL-C: what to do when they disagree.

The high correlation between apolipoprotein B (apoB) and non-high-density lipoprotein cholesterol (non-HDL-C) is the chief argument employed against introducing apoB into clinical practice. However, high correlation does mean that non-HDL-C and apoB will often yield similar clinical information. Nevertheless, the critical issue is not how often the two tests agree, but how often, and how substantially, they differ. In other words, how often would an apoB result change a clinical decision based on a value for non-HDL-C? This article presents a series of examples from prominent published studies in which apoB and non-HDL-C differ so dramatically that diagnosis and therapy would truly differ depending on which index was used by the physician. These examples establish that apoB and non-HDL-C are not clinical equivalents.