How to decide when to start lipid-modifying therapy

The decision to start lipid-modifying therapy should primarily be based on a patient’s ASCVD risk estimate. The patient’s results of a full lipid assessment and lifetime risk of cardiovascular events should also be considered.

Initiating therapy based on the patient’s ASCVD risk estimate is preferred to using lipid levels alone, because the Aus CVD risk calculator takes multiple interacting risk factors into account to estimate a patient’s risk. It thereby identifies people who might otherwise not be recognised as being at high risk (eg a patient whose lipid levels are not markedly elevated but who has other significant risk factors), as well as those at low risk who might otherwise be unnecessarily treated (eg a patient with moderate dyslipidaemia but no other risk factors). See Lipid-modifying therapy according to ASCVD risk estimate.

Also consider a patient’s lipid profile when deciding whether to start lipid-modifying therapy. The risk of atherosclerotic cardiovascular disease (ASCVD) increases with elevated low-density lipoprotein cholesterol (LDL-C) concentrations and/or triglyceride concentrations, particularly if associated with reduced high-density lipoprotein cholesterol (HDL-C) concentrations. Therapy is warranted if a patient has significantly elevated cholesterol (eg total cholesterol above 7.5 mmol/L), irrespective of their ASCVD risk estimate.

If a young person has elevated cholesterol levels, consideration should be given to their lifetime risk of cardiovascular events, which is related to cumulative exposure to elevated cholesterol levels. This is not sufficiently captured using ASCVD risk estimation tools alone. Extrapolating from cohort studies of patients with familial hypercholesterolaemia (who have elevated cholesterol concentrations at an early age), it is hypothesised that early control of elevated cholesterol concentrations in young patients will reduce lifetime risk. Patients may prefer to take lipid-lowering therapy to reduce this lifetime risk despite having an intermediate or low risk of a cardiovascular event in the next 5 years. It is therefore important to discuss the likely benefits versus harms of drug therapy with the patient; even a small reduction in risk may be considered worthwhile by some patients. If a decision is made to use lipid-modifying therapy in a patient at intermediate or low ASCVD risk, less aggressive treatment targets compared to those at very high or high risk are appropriate; see Target lipid concentrations according to ASCVD risk estimate for patients taking lipid-modifying therapy.

Secondary causes of dyslipidaemia should also be identified and managed. Lipid-modifying therapy is often required despite management of an underlying cause.

All patients with dyslipidaemia should be encouraged to adopt lifestyle modification measures to improve both their lipid profile and their ASCVD risk; see Nondrug therapy for lipid modification. If considering drug therapy, discuss the likely benefits and harms with the patient and consider patient preference.