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(updated July 2010)
In October 2009, the Canadian Cardiovascular Society published a revised guideline for the diagnosis and treatment of dyslipidemia and prevention of cardiovascular disease in adults(1). The table following includes a summary of the updated recommendations for initiation of therapy based on individual patient risk assessment, and primary lipid target values following treatment:
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Risk Level
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10 Year Risk of Cardiovascular Disease (CVD)*
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When to consider initiation of lipid lowering therapy
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Primary Lipid Target
LDL-C and
Apolipoprotein B (Apo B)
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High
(includes patients with diabetes, atherosclerotic disease or renal failure)
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≥ 20%
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Consider in all high risk patients
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LDL-C 2.0 mmol/L or
≥ 50% decrease from baseline or
Apo B < 0.8 g/L
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Moderate
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10% - 19%
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LDL-C > 3.5 mmol/L or
TC: HDL-C ratio > 5.0 or
hsCRP > 2.0 mg/L **
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LDL-C < 2.0 mmol/L or
≥ 50% decrease from baseline or
Apo B < 0.8 g/L
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Low
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< 10%
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LDL-C ≥ 5.0 mmol/L or
TC: HDL-C ratio > 6.0
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LDL-C ≥ 50% decrease from baseline
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* 10 year risk of cardiovascular disease (CVD) as calculated using the Framingham risk study (FRS) calculator tables.
** hsCRP is high sensitive C-reactive protein. Consider treatment when hsCRP is > 2.0 mg/L in men > 50 years or women > 60 years of age or where a family history of CVD exists and hsCRP levels indicate a moderate risk.
Primary Lipid Goals
The inclusion of apolipoprotein B (Apo B) and hsCRP in the lipid assessment is recognition of their roles as independent modifiers of CVD risk.
Apo B is the primary protein component of LDL, VLDL, IDL, and lipoprotein(a) and has been established as a good indicator of CVD risk. It has been included in the treatment target values as a possible substitute for LDL-C. The LDL-C value is routinely determined by calculation from cholesterol, HDL-C and triglycerides and is known to be unreliable in patients where the triglyceride concentration is > 4.52 mmol/L.
High sensitive C reactive protein (hsCRP) has been documented as a risk factor in development of CVD. Increased blood levels of hsCRP demonstrate a synergistic effect on the relative risk of CVD when combined with the individual’s lipid profile. In 2008, the Jupiter study illustrated the patients with hsCRP levels > 2 mg/L, even in the absence of elevated LDL-C may benefit from statin therapy(2). It should be noted that hsCRP measurement is only recommended for patients with LDL-C < 3.5 mmol/L and who are at moderate risk for CVD at ages > 50 for men or > 60 years of age for women(1).
Secondary Lipid Goals
The new recommendations include secondary (optional) lipid targets which may be considered after achieving the LDL-C goal. These include: triglyceride < 1.70 mmol/L, TC: HDL-C ratio < 4.0 and hsCRP < 2 mg/L. Clinical judgment is warranted to before a treatment plan is implemented to address potential secondary goals(1).
Laboratory Testing
Lipid levels should be determined after a 12-hour fast. A routine lipid profile including quantitation of serum total cholesterol (TC), HDL-C, TC: HDL-C ratio, LDL-C and triglycerides is recommended initially and then every 6-12 months. These assays may be ordered by checking “lipid assessment” on the OHIP laboratory requisition. Apo B measurement is available from LifeLabs but is not included on the OHIP schedule and is therefore a direct pay assay.
hsCRP: To obtain a reliable measure of hsCRP it is recommended that testing include 2 measurements taken 2 weeks apart. Patients should be well at the time of blood collection. The lower of the 2 assay values should be considered as the baseline value.
Where drug therapy is indicated, the addition of other markers of toxicity should be also considered. For example, ALT and CK may be requested to monitor potential side effects when statins are prescribed and creatinine levels in the presence of fibrate therapy. Under these circumstances more frequent monitoring may be necessary and when symptoms develop.
For more detailed information, physicians are referred to the detailed description of therapy and monitoring recommendations included in the original article published in the Canadian Journal of Cardiology(1).
References
1. Genest, J. McPherson, R., Frolich, J et. al. 2009 Canadian Cardiovascular Society/ Canadian Guideline for the diagnosis and treatment of dyslipidemia of cardiovascular disease in the adult – 2009 recommendations. Can. J. Cardio. Oct 2009 25: 567-579.
2. Ridker, PM, Danielson, E. Fonsecca, FAH, Genest J et. al. Rosuvastatin to prevent vascular events in men and women with elevated C reactive protein. N. Eng. J. Med. 2008: 359: 2195-2207.
Author:
Sheila Boss, PhD, FCACB is the Laboratory Director at LifeLabs, 100 International Blvd., Toronto.
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