The US Preventative Services Task Force (USPSTF) suggests that low to moderate statin use is beneficial for 40-75 years old individuals with no history of cardiovascular disease, one or more CVD risk factors and a CVD event risk level greater than 10%.
Cardiovascular disease (CVD), a leading cause of mortality and morbidity in North America, is characterized by conditions that affect the heart and blood vessels, such as coronary heart disease and cerebrovascular disease. Many studies have investigated the primary prevention of cardiovascular disease with the use of statins, a class of medications that lower lipid levels, especially cholesterol and low-density lipoprotein.
An article published by the JAMA outlined the recommendations by the USPSTF on the use of statins for the primary prevention of cardiovascular disease based on evidence from previous studies. As mentioned, the USPSTF recommends a low to moderate dose of statins in adults 40-75 years old who have no history of CVD, at least one CVD risk factor, and a calculated 10 year CVD event risk level of greater than 10%. Those who meet the same criteria, but with a 10 year CVD event risk level of 7.5% to 10% can be offered low to moderate statin doses based on professional judgment. However, there is insufficient evidence about the potential harms and benefits of using statins in individuals >75 years old to prevent the onset of CVD.
Identifying the risk factors, other than age and sex, for CVD is commonly used in determining whether statin use would benefit or harm the patient. Dyslipidemia, diabetes, hypertension and smoking are reliable risk factors for CVD, but family history has not been proven. The risk level can also be calculated using a pooled cohort equation that takes into account age, sex, race, cholesterol levels, systolic blood pressure, antihypertension treatment, presence of diabetes, and smoking status, but this tends to result in overestimation.
The USPSTF also reviewed the benefits and harms of screening for and treating of dyslipidemia in younger adults. Dyslipidemia is a risk factor for CVD characterized by elevated amounts of lipids in the blood. The USPSTF recognizes the reasoning that screening for dyslipidemia at an early age will identify those at risk for atherosclerosis, but there is lacking evidence that treating dyslipidemia in adults 21-39 years old has an effect on cardiovascular outcomes.
In terms of potential harms, statin use is associated with an increased risk of developing diabetes and surprisingly, cataract surgery. On the other hand, no sufficient evidence supports that statin use increases the risk of cancer, elevated liver enzymes, and muscle related problems despite previous associations. There are also no clear associations that cognitive function such as Alzheimer’s and Parkinson’s decrease with statin use because evidence is sparse, so further research is necessary.
Overall, incidence of CVD increases with the risk level with no known threshold at which event rates abruptly increase, so whether a small or moderate dosage should be used requires clinical judgment. Also, information pertaining to the use of statins with high dosage has been limited.
There are other limitations to consider, such as the uncertain estimation accuracy of risk calculators, the overall probability of CVD events in the general population, the known and unknown harms of statin use and the patient preferences. Thus, it is important for shared decision-making between clinicians and patients that informatively discusses the harms, benefits, and uncertainty about statin use.
Written By: Kim Gotera, BMSc