Purpose of review: Conventional methods, comparing the concentration of cholesterol to particle number as indices of cardiovascular risk, have not produced consistent results, in large part, because they treat these variables as independent and unrelated. However, although highly correlated, apolipoprotein B particles may contain a normal mass of cholesterol or may be cholesterol-depleted or cholesterol-enriched. Discordance analysis compares the predictive power of LDL-C and non-HDL-C to apolipoprotein B and LDL particle numbers in patients in whom they differ, that is, in whom they are discordant. The advantage of discordance analysis is that the results are not diluted by concordant data in which risk predictions cannot differ.
Recent findings: The evidence, to date, consistently demonstrates that apolipoprotein B and LDL particle numbers are more accurate indices of cardiovascular risk than LDL-C or non-HDL-C.
Summary: Discordance analysis is a methodological advance that allows the clinical value of closely correlated variables to be determined and demonstrates that cardiovascular risk is more closely related to the number of atherogenic particles than to the total mass of cholesterol within them.