Framingham Risk Calculator
Using Canadian Lipid Guidelines

An Evidence-Based Alternative:

The Canadian guidelines are complex, more inclusive, and, because they create a lot of work for both physician and patient, it is likely that compliance with statin use will be influenced adversely.  The most important factor in pharmacologic treatment and primary prevention is that the patient be given a statin.  If dosing is simpler and cheaper using a generic fixed dose statin, and if lab tests are minimized by not utilizing hs-CRP and LDL targets, compliance may improve.  Evidence for this approach is discussed in a Canadian Family Physician article April of 2011, and is available online at http://www.cfp.ca/content/57/4/417.full.pdf+html

Statins actually produce a similar benefit in preventing CVS end points across all levels of risk, with approximately 20% reduction in major vascular events for each 1 mmol/L reduction in LDL (1,2).  The most individual benefit is seen in those with the highest Framingham risk score (FRS), as they are at highest risk.  On a population basis, however, most events still happen to patients with a low FRS.  Treating low risk patients requires treating large numbers of people to prevent one event.  Numbers needed to treat for each calculation are included assuming that the patient will be given 40 mg. of simvastatin and achieve a 27% reduction in vascular events.  The statin used is of less importance than actually getting the patient to take the medication (1).  The Heart Protection Study (3) currently gives us the best evidence for this approach.  Although this was a secondary prevention study, relative benefit is actually similar for primary prevention, even though absolute numbers benefiting are smaller.  The physician and patient can better decide individual threshold for lipid lowering therapy based on NNT if they are not comfortable with guideline recommendations.

The alternative approach would be to calculate risk without the JUPITER criteria.  This would skip the hs-CRP input and avoid using LDL levels as a trigger for treatment.  All patients at high risk would be treated.  A threshold for treatment of moderate risk patients could be selected based on guideline recommendations and NNT.  Patients opting for treatment would simply be given 40 mg. of generic simvastatin (half the 80 mg. tablet to reduce cost).  Lab followup would depend on the physician’s perception of need for liver enzymes, as LDL would not be followed.  40 mg. of atorvastatin could be used alternatively for those at higher risk.  Although there is no consistent evidence, one presumes that NNT for atorvastatin would be lower.

1. Mills EJ, et al.  Primary prevention of cardiovascular mortality and events with statin treatment. J American Coll Cardiol 2008; 52(22): 1769-81.

2. Pignone M. Treatment of lipids (including hypercholesterolemia) in primary prevention. In: Freeman MW, Rind DM, eds. UpToDate. 19.1; 28 February 2011.

3. Heart Protection Study Collaborative Group.  C-reactive protein concentration and the vascular benefits of statin therapy: an analysis of 20 536 patients in the Heart Protection Study.