Diagnosis and Assessment of Disease
Step 2: Establish Goals or Therapy (values relate to the degree of risk present)
ÎLDL is the primary target of therapy (Table 3).
• Historically, the cholesterol content of LDL particles—LDL-C—has been the laboratory test used to estimate the number of LDL particles present.
• Recent data have demonstrated that the amount of cholesterol carried in LDL particles is highly variable between individuals. As a result, LDL particle number may vary substantially at a given LDL-C value.
• Recent recommendations advocate managing high-risk and moderate-high risk patients to both LDL-C and LDL particle number (apoB3, 20
• Target values for LDL-C and LDL particle number are advocated that correspond to a population equivalent level (ie, the 20th
targets appropriate for the CHD risk category present. Because CV risk tracks with particle number, measures of LDL particle number, not cholesterol, are the best indicators of the adequacy of LDL lowering therapy.
or NMR LDL-P3 ) and 50th percentile).3, 5, 21
ÎNon-HDL-C (total cholesterol minus HDL cholesterol) is a secondary target of therapy.
• Non-HDL-C is a superior predictor of risk versus LDL-C independent of the TG level.25
Table 4. Alternate Measures of LDL Quantity (Cholesterol and Particle Number as Targets of Therapy)
Characteristics Biomarker
Analytic and Clinical Issues
Cholesterol Related LDL Targets
Cholesterol measures estimate LDL particle number based on cholesterol carried by lipoproteins.
Due to variability in the cholesterol content of LDL particles, alternate LDL quantity measures (LDL-C or non-HDL-C versus LDL particle number) are frequently discordant.
Expert Recommendations
Public policy guidelines (such as Adult Treatment Panel [ATP] III) advise initial management to LDL-C and non-HDL-C targets to lower relative cardiovascular risk in the general population.
a
LDL Particle Number Targetsa
Particle number tests measure the number of circulating LDL particles regardless of cholesterol carried by lipoproteins.
When alternate LDL measures (LDL-C or non-HDL-C versus LDL particle number) are discordant CV risk tracks with LDL-P rather than LDL-C or non-HDL-C.
Recent expert panels advise treating to LDL particle number targets (either NMR LDL-P or measured Apo B), in addition to LDL-C and non-HDL-C, to optimize management of moderate and high risk individuals.
NOTE: When LDL particle number is elevated, CHD events are increased. When LDL particle number is low, CHD events are decreased. If cholesterol (LDL-C and non-HDL-C) and LDL particle number measures are discordant, risk tracks with LDL particle number. Hence, LDL particle number is the final target of therapy for all patients.
10
• Direct measures of LDL particle number, such as apolipoprotein B100 (apoB) or LDL-P measured by NMR, have been shown to be more strongly associated with CHD risk than LDL-C.1, 3
