Dyslipidemia

Earn CME/CE in your profession:


Continuing Education Activity

Dyslipidemia refers to abnormal levels of lipids in the bloodstream, which poses a significant risk factor for cardiovascular (CV) diseases. Dysregulation in these lipid levels, whether due to genetic predispositions or lifestyle factors, can lead to atherosclerosis and other CV complications. Diagnosis often relies on lipid profile tests, with recommended target levels for optimal CV health. Treatment strategies work to mitigate risks by targeting specific lipid abnormalities, emphasizing lifestyle modifications, and considering comorbidities to individualize care. Given the multifaceted nature of dyslipidemia management, a multidisciplinary approach is essential for comprehensive patient care.

This course is designed to provide healthcare professionals with a comprehensive understanding of dyslipidemia, its diagnosis, treatment strategies, and the importance of a multidisciplinary approach in patient care. Throughout this activity, learners explore various aspects of dyslipidemia management. Essential lipids such as cholesterol, low-density lipoprotein, high-density lipoprotein, and triglycerides, evaluating their roles in physiological processes and the implications of dysregulation are discussed. One of the key themes of this course is the vital role of interprofessional collaboration in dyslipidemia management. Learners gain insights into how collaborative efforts among healthcare professionals, including cardiologists, endocrinologists, nurses, pharmacists, dietitians, and educators, contribute to developing tailored treatment plans for managing dyslipidemia.

Objectives:

  • Evaluate the etiology and mechanisms underlying dyslipidemia, including impaired lipoprotein synthesis, secretion, and clearance.

  • Identify the risk factors and clinical presentations indicative of dyslipidemia.

  • Differentiate the management options for dyslipidemia, including lifestyle modifications, pharmacological interventions, and potential benefits or risks of each class of lipid-lowering medications.

  • Implement patient-centered care and shared decision-making in dyslipidemia management to include collaborative efforts between healthcare professionals.

Introduction

Lipids, such as cholesterol or triglycerides, are absorbed from the intestines and carried throughout the body via lipoproteins for energy, steroid production, or bile acid formation. Major contributors to these pathways are cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, and high-density lipoprotein (HDL). An imbalance of any of these factors, either from organic or nonorganic causes, can lead to dyslipidemia.[1] Dyslipidemia results in abnormal levels of lipids (fats) in the blood that can increase the risk of cardiovascular diseases.

Lipids include LDL cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides. Dyslipidemia is classified into 2 types: primary and secondary. Primary dyslipidemia is inherited and caused by genetic mutations that affect lipid metabolism.[2] Secondary dyslipidemia is acquired and caused by lifestyle factors or other medical conditions that alter lipid levels. The most common forms of dyslipidemia are:

  • High LDL cholesterol is considered “bad” cholesterol because it can form plaques in the arteries and reduce blood flow.
  • Low HDL cholesterol is considered “good” cholesterol because it can help remove LDL from the blood and protect against atherosclerosis.
  • High triglycerides are stored in fat cells and released as energy when needed. High triglycerides can also contribute to plaque formation and inflammation in the arteries.
  • High total cholesterol is the sum of LDL, HDL, and half of the triglyceride level. High total cholesterol can indicate an increased risk of heart disease and stroke.[3]

Dyslipidemia usually does not cause any symptoms, but it can be detected by a blood test measuring different lipids levels. The optimal lipid level varies depending on the individual’s age, sex, and other risk factors, but generally, the following ranges are recommended:

  • LDL cholesterol: less than 100 mg/dL
  • HDL cholesterol: more than 40 mg/dL for men and more than 50 mg/dL for women
  • Triglycerides: less than 150 mg/dL
  • Total cholesterol: less than 200 mg/dL

Treating dyslipidemia depends on the type and severity of the condition and the presence of other risk factors such as diabetes, hypertension, obesity, or smoking. The main goals of treatment are to lower LDL cholesterol, raise HDL cholesterol, and reduce triglycerides.

Preventing dyslipidemia is essential to reduce the risk of cardiovascular complications and improve the quality of life. The prevention strategies include:

  • Screening for dyslipidemia regularly, especially for people with a family history or other risk factors. The frequency and type of screening depend on the individual’s age, sex, and health status, but generally, a lipid profile test is recommended every 4 to 6 years for adults and every 2 years for children and adolescents.
  • Adopting a healthy lifestyle by eating a balanced diet with plenty of fruits, vegetables, whole grains, lean proteins, and healthy fats, such as omega-3 fatty acids from fish, nuts, and seeds. Avoid foods high in cholesterol, saturated fats, trans fats, added sugars, and salt. If possible, engage in physical activity for at least 150 minutes weekly. Maintaining a healthy weight and body mass index, quitting smoking, and limiting alcohol intake are all recommended.
  • Comorbidities such as diabetes, hypertension, hypothyroidism, chronic kidney disease, or liver disease can affect lipid levels or increase the risk of cardiovascular disease; therefore, it is important to remain compliant with any medications.[4]

Etiology

Dyslipidemia, characterized by aberrations in lipid metabolism, has multifaceted etiologies influenced by genetic, environmental, and lifestyle factors. Understanding these etiologies is crucial for developing targeted interventions and preventive strategies. Dyslipidemia can be classified into 2 types based on the etiology: 

Primary Dyslipidemia

This type of dyslipidemia is caused by genetic mutations that affect the metabolism of lipids. Primary dyslipidemia can be inherited as an autosomal dominant, autosomal recessive, or X-linked. Some examples of primary dyslipidemia are familial hypercholesterolemia, familial hypertriglyceridemia, familial combined hyperlipidemia, and familial dysbetalipoproteinemia. The estimated prevalence of familial hypercholesterolemia ranges from 1 in 500 to 1 in 250 in most populations. Still, it can be as high as 1 in 67 in some ethnic groups, such as Afrikaners, French Canadians, and Lebanese.[5] The prevalence of familial hypertriglyceridemia is estimated at 1 in 500 in the general population. However, it is higher in certain populations, such as Hispanics and Native Americans.[6] The prevalence of familial combined hyperlipidemia is estimated at 1 in 100 in the general population. However, it can be higher in patients with premature coronary artery disease. The prevalence of familial dysbetalipoproteinemia is estimated at 1 in 10,000 in the general population, but it can be higher in patients with diabetes or obesity. 

The mechanisms of primary dyslipidemia involve defects in the synthesis, transport, or degradation of lipoproteins, which are the main carriers of lipids in the blood. These defects result in the accumulation or deficiency of lipoproteins and lipids in the blood, increasing the risk of atherosclerosis and cardiovascular disease. For example, familial hypercholesterolemia is caused by mutations in the LDL receptor gene, impairing LDL cholesterol uptake from the blood and leading to high LDL cholesterol levels and premature atherosclerosis.

Familial hypertriglyceridemia is caused by mutations in the LPL gene or the apo C-II gene, which impair the hydrolysis of triglycerides in chylomicrons and very low-density lipoproteins (VLDL), leading to high triglyceride levels and pancreatitis. Familial combined hyperlipidemia is caused by the overproduction of apo B-containing lipoproteins, such as VLDL and LDL, by the liver, leading to high cholesterol and triglyceride levels and insulin resistance. Familial dysbetalipoproteinemia is caused by mutations in the apo E gene, which impair the clearance of chylomicron and VLDL from the blood, leading to high cholesterol and triglyceride levels and xanthomas.[7][8]

Secondary Dyslipidemia

This type of dyslipidemia is caused by lifestyle factors or other medical conditions that alter the levels of lipids in the blood. Secondary dyslipidemia is reversible or modifiable by addressing the underlying cause. Some examples of secondary dyslipidemia risk factors include physical inactivity, unhealthy nutrition, obesity, diabetes, hypothyroidism, chronic kidney disease, liver disease, alcohol abuse, smoking, and the use of certain drugs.[9] Results from a study in the United States (US) found that 28% of new patients referred to a lipid clinic had 1 or more potential causes of secondary dyslipidemia, with excessive alcohol intake (10%) and uncontrolled diabetes mellitus (8%) as the most prevalent. 

  • For example, obesity is associated with increased production of very low-density lipoprotein and decreased liver clearance of chylomicrons, leading to high triglyceride and low high-density lipoprotein cholesterol levels.
  • Diabetes mellitus is associated with insulin resistance and hyperglycemia, impairing triglyceride lipolysis and the uptake of LDL cholesterol; this leads to high triglyceride and LDL cholesterol levels and low HDL cholesterol levels.
  • Hypothyroidism is associated with decreased expression of LDL receptors and lipoprotein lipase, which impair the clearance of LDL cholesterol and triglycerides from the blood, leading to high LDL cholesterol and triglyceride levels.
  • Chronic kidney disease is associated with impaired catabolism of apo B-containing lipoproteins and reduced activity of lipoprotein lipase and hepatic lipase, which impair the clearance of triglycerides and cholesterol from the blood, leading to high triglyceride and LDL cholesterol levels and low HDL cholesterol levels. 
  • Liver disease is associated with impaired synthesis and secretion of lipoproteins and bile acids, which impair the transport and excretion of cholesterol and triglycerides from the liver, leading to high or low cholesterol and triglyceride levels depending on the type and severity of the liver disease.
  • Alcohol abuse is associated with increased synthesis of VLDL and decreased oxidation of fatty acids by the liver, leading to high triglyceride levels.
  • Smoking is associated with increased oxidative stress and inflammation, which impair the function and synthesis of HDL cholesterol, leading to low HDL cholesterol levels.
  • Use of certain drugs, such as corticosteroids, beta-blockers, oral contraceptives, and antiretroviral agents, can affect the metabolism of lipids and lipoproteins by various mechanisms, leading to high or low cholesterol and triglyceride levels depending on the type and dose of the drug. 

Epidemiology

Dyslipidemia is a global public health problem that affects millions of people and increases the risk of cardiovascular disease, the leading cause of death worldwide. The epidemiology of dyslipidemia varies by region, age, sex, and ethnicity and is influenced by genetic and environmental factors.[10] According to a systematic review protocol, the global prevalence of dyslipidemia in adults is estimated to range from 20% to 80%, depending on the definition and criteria used.[11] However, comprehensive and updated data on the epidemiology of dyslipidemia is currently lacking in different populations and settings. The awareness, treatment, and control of dyslipidemia are also suboptimal in many countries, especially in low- and middle-income countries.[11] From 2005 to 2008, 33.5% of U.S. adults older than 20 had high LDL levels. Of these individuals with elevated LDL levels, only 48.1% received treatment, and 33.2% had LDL control. The prevalence of LDL control was lowest amongst uninsured individuals, Mexican Americans, or those who had income below the poverty level.[12]

The incidence and mortality of dyslipidemia are challenging to measure directly, as dyslipidemia is usually asymptomatic and often coexists with other risk factors, such as hypertension, diabetes, obesity, and smoking. Therefore, most studies use surrogate endpoints, such as cardiovascular events, to assess the impact of dyslipidemia on morbidity and mortality. A large-scale trial showed that lowering LDL cholesterol by 1 mmol/L reduced the risk of major vascular events by about 20%, regardless of the initial LDL level. A meta-analysis of 26 randomized trials found that statin therapy reduced the risk of all-cause mortality by 10%, coronary mortality by 18%, and stroke mortality by 9%. The economic burden of dyslipidemia is also substantial, as it increases the direct and indirect costs of healthcare and productivity losses. Results from a US study showed that the estimated annual cost of dyslipidemia was $34.4 billion in 2006, of which $19.7 billion was attributed to direct medical costs and $14.7 billion to indirect costs.[13] 

The epidemiology of dyslipidemia also reveals gender differences, as women tend to have higher HDL cholesterol and lower LDL cholesterol than men, but this advantage diminishes after menopause. Women are also less likely to receive adequate screening, diagnosis, and treatment for dyslipidemia than men and have worse outcomes after cardiovascular events. The prevalence of dyslipidemia in children and adolescents is increasing, especially in developed countries, due to the rising rates of obesity, sedentary lifestyles, and unhealthy diets.[14] Results from another US study reported that 7% of children and adolescents aged 6 to 19 had high total cholesterol, and 22% had at least one abnormal lipid level. Dyslipidemia in childhood can persist into adulthood and increase the risk of premature cardiovascular disease. Dyslipidemia is a modifiable risk factor for cardiovascular disease, and prevention and management are essential to reduce the global burden of morbidity and mortality. The epidemiology of dyslipidemia provides valuable information for developing and implementing effective strategies to improve dyslipidemia awareness, treatment, and control in different populations and settings.

Pathophysiology

Understanding the pathophysiology of dyslipidemia elucidates the role of a spectrum of interconnected metabolic and cardiovascular disturbances. Dyslipidemia can cause inflammation, oxidative stress, cardiovascular diseases, and other metabolic dysfunctions by different mechanisms, such as:

Inflammation

Elevated levels of LDL and triglyceride-rich lipoproteins promote their retention in arterial walls; this can trigger an inflammatory response in the blood vessels, contributing to the development and progression of atherosclerosis.[15] Atherosclerosis is the accumulation of fatty plaques in the arterial walls, which can reduce blood flow and increase the risk of thrombosis. Dyslipidemia can activate inflammatory cells, such as macrophages and T cells, and inflammatory mediators, such as cytokines and chemokines--which can infiltrate and damage the endothelium (the inner lining of the blood vessels). Dyslipidemia can also increase the expression of adhesion molecules, such as intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, which can facilitate the attachment and migration of inflammatory cells into the subendothelial space. Dyslipidemia can also modulate the function of endothelial progenitor cells (EPCs), which are involved in the repair and regeneration of the endothelium. Dyslipidemia can impair the number and activity of EPCs, which compromise endothelial integrity and function.

Oxidative Stress

LDL particles, when retained in arterial walls, undergo oxidative modifications. Oxidized LDL becomes pro-inflammatory and pro-atherogenic; this can increase the production of reactive oxygen species (ROS), unstable molecules that damage cells and tissues by oxidizing components such as lipids, proteins, and deoxyribonucleic acid. Dyslipidemia can also decrease the levels of antioxidants, which can neutralize ROS and protect the cells and tissues from oxidative damage.[16]

Dyslipidemia can induce oxidative stress by various mechanisms, such as:

  • Oxidation of LDL cholesterol: LDL cholesterol is the primary carrier of cholesterol in the blood and the main target of oxidation by ROS. Oxidized LDL (oxLDL) is more atherogenic than native LDL, as it can stimulate cholesterol uptake by macrophages, leading to the formation of foam cells, which are the hallmark of atherosclerotic plaques. OxLDL can also induce the expression of inflammatory mediators, such as tumor necrosis factor-alpha and interleukin-6, and the activation of nuclear factor-kappa B, a transcription factor that regulates the expression of genes involved in inflammation and immunity. OxLDL can also impair the function of endothelial nitric oxide synthase, an enzyme that produces nitric oxide, a vasodilator and anti-inflammatory molecule.
  • Impairment of HDL cholesterol: HDL cholesterol is the main carrier of cholesterol from the peripheral tissues to the liver for excretion, and it has anti-inflammatory and antioxidant properties. Dyslipidemia can impair the function of HDL cholesterol by reducing its levels, altering its composition, or modifying its enzymes and receptors. Dyslipidemia can also increase the transfer of cholesterol esters from HDL to LDL and VLDL by using cholesteryl ester transfer protein, reducing HDL's ability to remove excess cholesterol from blood vessels. Dyslipidemia can impair the activity of paraoxonase-1, an enzyme associated with HDL that protects LDL from oxidation.[15]

Cardiovascular Diseases

Dyslipidemia can increase the risk of cardiovascular diseases, such as coronary artery disease, peripheral artery disease, stroke, and heart failure, by promoting atherosclerosis and its complications. Dyslipidemia can also affect the function of the heart and the blood vessels by impairing the production and availability of nitric oxide, a key regulator of vascular tone, blood pressure, and platelet aggregation. Dyslipidemia can induce endothelial dysfunction, the impairment of the ability of the endothelium to maintain vascular homeostasis and to respond to physiological stimuli. Dyslipidemia can also affect the structure and function of the cardiac muscle, leading to cardiac hypertrophy, fibrosis, and arrhythmias.

Other Metabolic Dysfunctions

Additional effects exist on the metabolism of other organs and systems, such as the liver, the pancreas, the adipose tissue, and the skeletal muscle, by altering lipid and glucose metabolism, insulin sensitivity, and inflammatory status. Dyslipidemia can also interact with other metabolic disorders, such as obesity, diabetes, and metabolic syndrome, and exacerbate complications.[17]

History and Physical

Understanding the signs and symptoms of dyslipidemia is crucial for timely intervention and preventing associated complications. As dyslipidemia often progresses silently, routine lipid screening (especially in high-risk populations) remains a cornerstone for early detection and effective management. Clinicians should consider the broader clinical context, including family history and risk factors, to guide appropriate interventions and reduce the burden of cardiovascular diseases associated with dyslipidemia. Pertinent social history would include tobacco use or specific details about diet. Past medical history is vital in identifying patients needing primary prevention versus secondary prevention if statin therapy requires initiation. Lastly, family history is important to identify familial hypercholesterolemia.

Some patients with severe or untreated dyslipidemia may develop signs and symptoms related to the complications of dyslipidemia, such as atherosclerosis, coronary artery disease, peripheral artery disease, stroke, and heart failure. Some of the possible signs and symptoms of dyslipidemia are: 

  • Xanthomas: These are yellowish fat deposits visible on the skin of the eyelids (xanthelasma), palms, tendons, or other areas. They can form plaques or nodules and indicate high levels of cholesterol or triglycerides in the blood.
  • Arcus senilis: This is a gray or white ring around the eye’s cornea that is caused by cholesterol depositing in the corneal margin and indicates high cholesterol levels in the blood. This is more common in older people but can also occur in younger people with dyslipidemia.
  • Lipemia retinalis: This condition produces a milky appearance in the retinal vessels due to high blood triglyceride levels. Lipemia retinalis is a rare condition that can cause blurred vision and may indicate severe hypertriglyceridemia.
  • Lower limb ischemia: This type of ischemia is a common symptom of peripheral artery disease, caused by the narrowing or blockage of the arteries that supply blood to the legs due to atherosclerosis; this condition is usually characterized by pain or cramping during physical activity (walking or exercising) and improves with rest. Lower limb ischemia may indicate high levels of LDL, cholesterol, or triglycerides in the blood.
  • Angina: This is a common symptom of coronary artery disease, caused by the narrowing or blockage of the arteries that supply blood to the heart due to atherosclerosis. The pain usually occurs when the heart needs more oxygen, such as during physical or emotional stress, and may radiate to the neck, jaw, shoulders, or back. Angina may indicate high levels of LDL cholesterol or triglycerides in the blood.
  • Transient ischemic attacks and strokes: Dyslipidemia increases the risk of atherosclerosis in cerebral arteries, contributing to sudden interruption of blood flow to the brain due to a clot or a bleed in weakened blood vessel walls. Symptoms may include sudden weakness, slurred speech, or visual disturbances.[18][19]

Evaluation

Dyslipidemia, a crucial risk factor for cardiovascular diseases, necessitates comprehensive diagnostic investigations for accurate assessment. The primary evaluation tool for dyslipidemia is a fasting lipid panel comprising total cholesterol, LDL, HDL, and triglycerides. Some debate is prevalent on the age at which dyslipidemia screening should start.

Screening Guidelines and Tests:

  • The National Cholesterol Education Program provides the Adult Treatment Panel III—widely acknowledged guidelines for dyslipidemia screening. Guidelines recommend a fasting lipid panel every 5 years for adults 20 years and older.
  • The US Preventive Services Task Force recommends lipid screening in men 35 years and older (as well as men who are high-risk, age 20 to 35) and women 45 years and older (as well as high-risk individuals between 20 and 45 years). Younger adults are advised to undergo screening if they have cardiovascular risk factors. Other recommendations suggest getting fasting lipid panels for all individuals who are between 20 to 78 at least every 5 years if no atherosclerotic disease is present.[20]
  • The American Academy of Pediatrics recommends screening for dyslipidemia in children and adolescents aged 9 to 11 years and 17 to 21 years, regardless of risk factors, and selective screening for those aged 2 to 8 years and 12 to 16 years who have a family history of dyslipidemia or CVD, or other risk factors, such as obesity, diabetes, hypertension, or smoking.[21]
  • The American Heart Association and American College of Cardiology recommendations for Cardiovascular Risk Assessment guidelines use a risk calculator to estimate the 10-year risk of atherosclerotic cardiovascular disease, which includes coronary heart disease, stroke, and peripheral artery disease. The risk calculator takes into account the age, sex, race, total cholesterol, HDL, systolic blood pressure, antihypertensive therapy, diabetes, and smoking status of the individual. The risk categories are: low risk (<5%), borderline risk (5% to 7.4%), intermediate risk (7.5% to 19.9%), and high risk (≥20%). These guidelines suggest routine lipid screening for patients between 40 and 75 years every 4 to 6 years. High-risk individuals, including those with diabetes or a history of cardiovascular disease, may require more frequent assessments.
  • The National Institute of Health and Clinical Excellence provides comprehensive guidelines on lipid modification for cardiovascular risk reduction. The guideline uses the QRISK3 tool, which estimates the 10-year risk of cardiovascular disease, including coronary heart disease, stroke, and transient ischemic attack. The QRISK3 tool considers the age, sex, ethnicity, postcode, smoking status, body mass index, systolic blood pressure, cholesterol ratio, atrial fibrillation, diabetes, chronic kidney disease, rheumatoid arthritis, and family history of the individual. The risk categories are: low risk (<10%), moderate risk (10%-19%), and high risk (≥20%).

Classification of Lipid Levels

Total cholesterol

  • Desirable: <200 mg/dL
  • Borderline high: 200 mg/dL to 239 mg/dL
  • High: ≥240 mg/dL

Low-density lipoprotein cholesterol

  • Optimal: <100 mg/dL 
  • Near optimal/above optimal: 100 mg/dL to 129 mg/dL
  • Borderline high: 130 mg/dL to 159 mg/dL
  • High: 160 mg/dL to 189 mg/dL
  • Very high: ≥190 mg/dL

High-density lipoprotein cholesterol

  • Low: <40 mg/dL (men), <50 mg/dL (women)
  • High: ≥60 mg/dL

Triglycerides

  • Normal: <150 mg/dL
  • Borderline high: 150 mg/dL to 199 mg/dL
  • High: 200 mg/dL to 499 mg/dL
  • Very high: ≥500 mg/dL

Classification of dyslipidemia is subdivided into 5 different categories, according to Frederickson phenotype:

  • Phenotype I is an abnormality of chylomicrons and will result in triglycerides greater than 99 percentiles. 
  • Phenotype IIa consists mainly of LDL cholesterol abnormality and will have a total cholesterol concentration greater than 90 percentile and possibly apolipoprotein B greater than 90 percentile. 
  • Phenotype IIb consists of abnormality in LDL and VLDL cholesterol. This type will result in total cholesterol or triglycerides greater than the 90 percentile and apolipoprotein greater than the 90 percentile. 
  • Phenotype III is an abnormality in VLDL remnants and chylomicrons, which results in elevated total cholesterol and triglycerides greater than 90 percentile. 
  • Phenotype IV is mainly when VLDL is abnormal and results in total cholesterol greater than 90 percentile. This type can also present with triglycerides greater than 90 percentile and low HDL. 
  • Phenotype V is when chylomicrons and VLDL are abnormal, and triglycerides are greater than 99 percentiles.[6][22]

Treatment / Management

Managing dyslipidemia initially involves lifestyle modifications, including those listed below.

Dietary Modification

Dietary changes include reducing the intake of saturated and trans fats, cholesterol, and refined carbohydrates and increasing the intake of unsaturated fats, fiber, plant sterols, and antioxidants. A healthy diet for dyslipidemia management should follow the principles of the Mediterranean diet, the Dietary Approaches to Stop Hypertension diet or the Therapeutic Lifestyle Changes diet. These diets lower the LDL, triglyceride, and non-HDL levels, increase the HDL levels, and reduce blood pressure, inflammation, and oxidative stress.[23]

Physical Activity

Physical activity is an important component of lifestyle modification, as it can improve the lipid profile, lower blood pressure, enhance insulin sensitivity, and promote weight loss. Physical activity can also reduce cardiovascular risk by improving endothelial function, reducing inflammation, and preventing thrombosis. The recommended amount and intensity of physical activity for dyslipidemia management vary depending on the patient’s age, health status, and goals. The American Heart (AHA) Association suggests that adults should aim for at least 150 minutes of moderate-intensity aerobic exercise, 75 minutes of vigorous-intensity aerobic exercise per week, or a combination of both. Moderate-intensity aerobic exercise includes brisk walking, cycling, swimming, or dancing. Vigorous-intensity aerobic exercise includes running, jumping rope, or playing sports. In addition, the AHA recommends that adults should also perform muscle-strengthening exercises at least twice a week, involving all major muscle groups. Examples of muscle-strengthening exercises include lifting weights, doing push-ups, or using resistance bands. Patients with dyslipidemia should consult their clinician before starting or increasing physical activity and follow the appropriate safety precautions and guidelines.[24]

Weight Management

Weight management is another key aspect of lifestyle modification, as it can improve the lipid profile, lower blood pressure, and reduce the risk of diabetes and metabolic syndrome. Weight management involves achieving and maintaining a healthy body weight, defined as a body mass index of 18.5 to 24.9 kg/m2. Patients with dyslipidemia who are overweight or obese should aim for a gradual and sustained weight loss of 5% to 10% of their initial body weight over 6 to 12 months, which can be achieved by reducing calorie intake and increasing physical activity.

Smoking Cessation

Smoking cessation can improve the lipid profile, lower blood pressure, and reduce the risk of CVD and other chronic diseases. Smoking can adversely affect the lipid profile by increasing the LDL, triglyceride, and non-HDL levels and decreasing the HDL level. Smoking can also increase the CVD risk by damaging the endothelium, increasing inflammation, promoting LDL oxidation, enhancing platelet aggregation, and inducing vasoconstriction. Quitting smoking can reverse these effects and improve the lipid profile and the CVD risk within weeks to months. 

Treatment Strategies

The first-line treatment for dyslipidemia is statins that inhibit 3-hydroxy-3methylglutaryl-coenzyme A reductase. Patients with clinically significant atherosclerotic cardiovascular disease (ASCVD) (acute coronary syndromes, history of myocardial infarction, stable or unstable angina, arterial revascularization, and stroke) and are aged less than 75 should be prescribed a high-intensity statin. Patients 75 years or older with clinical ASCVD should be prescribed a moderate-intensity statin.

High-intensity statin therapy should start if the patient is aged 40 to 75, has LDL greater than or equal to 190 mg/dL, or has a history of diabetes and LDL between 70 to 189 mg/dL. Patients should be on a moderate or high-intensity statin if they are 40 to 75 years, have LDL between 70 to 189 mg/dL, and have a 10-year ASCVD greater than or equal to 7.5%. The clinician-patient discussion should be undertaken to discuss the introduction of high or moderate-intensity statin in situations such as less than 5% to 7.5% 10-year ASCVD risk.[25] 

For primary prevention, statin therapy should lower LDL by approximately 30% to less than 50% with a moderate-intensity statin and greater than or equal to 50% with a high-intensity statin. High-intensity statins are atorvastatin, 40 or 80 mg, and rosuvastatin, 20 mg. Some moderate-intensity statins are atorvastatin 10 mg, rosuvastatin 10 mg, simvastatin 20 or 40 mg, and pravastatin 10 mg.[26]

For secondary prevention, as defined by a patient with coronary artery disease, a target goal is set for LDL less than 70 mg/dL after being placed on a high-intensity statin for 6 weeks. If this goal is not met and LDL is significantly greater than 70, then combination therapy should be started in addition to high-intensity statin. The LDL goal should remain less than 70 mg/dL if the patient is not high-risk. If the patient is high risk (eg, had acute coronary syndrome in the last year, familial hypercholesterolemia, diabetes, chronic kidney disease stage 3 or 4, atherosclerotic cardiovascular disease event, or the need for revascularization while on a statin), the LDL goal is less than 50 mg/dL, and another agent is added. 

Currently, 2 classes of medications are recommended with statin therapy because they decrease cardiovascular outcomes. One of these is ezetimibe, which inhibits the absorption of cholesterol. Combined with statin therapy, this drug can lower LDL by 25%. Another category targets proprotein convertase subtilisin/kexin type 9 (PCSK9), which regulates the LDL receptor. An increase in PSCK9 decreases LDL receptors and increases LDL levels in the blood. PCSK9 inhibitors are monoclonal antibodies that bind PCSK9 and decrease LDL levels. The new agent, inclisiran, is an interfering ribonucleic acid drug that stops the production of PCSK9 with twice-yearly dosing.[27] This agent is beneficial in patients who are intolerant of LDL-lowering medications. Icosapent ethyl is a Food and Drug Administration-approved medication that reduces cardiovascular risk in patients with elevated triglycerides in addition to maximal statin therapy. Bempedoic acid is another drug that is an option for people intolerant to statins in combination with ezetimibe. This drug works by inhibiting adenosine triphosphate citrate lyase, which increases cholesterol in the liver and decreases levels. Many new medications are being researched to help lower cholesterol levels and prevent cardiovascular events.

Other categories of treatment not shown to reduce cardiovascular events but have been useful in dyslipidemia therapy are bile acid sequestrants such as cholestyramine, colestipol, and colesevelam, which decrease bile acid reabsorption, therefore increasing clearance of LDL. Fibric acid derivatives (fibrates) are peroxisome proliferator-activated receptor agonists. These increase HDL and reduce triglycerides. However, in combination with statins, they can increase the risk of myopathy and rhabdomyolysis, which can cause generalized muscle pain. Current guidelines recommend against the use of statins and gemfibrozil. Niacin increases HDL and reduces VLDL, decreasing LDL but with a significant side effect profile. Aspirin can decrease the occurrence of this side effect.[28][29][30][31][32][33]

Different guidelines are available that provide recommendations and targets for the pharmacological treatment of dyslipidemia, such as the US Department of Veterans Affairs and Department of Defense, the European Society of Cardiology and European Atherosclerosis Society, the Canadian Cardiovascular Society, and the American College of Cardiology and American Heart Association.[34]

Different guidelines have been developed to provide recommendations and targets for the pharmacological treatment of dyslipidemia (see Table. Recommendations and Targets for Pharmacologically Treating Dyslipidemia), such as the U.S. Department of Veterans Affairs and Department of Defense (VA/DoD), the European Society of Cardiology (ESC) and European Atherosclerosis Society (EAS), the Canadian Cardiovascular Society (CCS), and the American College of Cardiology (ACC) and American Heart Association (AHA).[34]

Table. Recommendations and Targets for Pharmacologically Treating Dyslipidemia 

  LDL Target (mg/dL) Non-HDL Target (mg/dL) First-line Treatment Add-on Treatment
VA/DoD

<100 for patients with CVD or diabetes, <130 for patients without CVD or diabetes

<130 for patients with CVD or diabetes or <160 for patients without CVD or diabetes Moderate-dose statins for all patients High-dose statins, ezetimibe, or PCSK9 inhibitors for higher-risk patients
ESC/EAS <55 for patients at very high risk, <70 for patients at high risk, <100 for patients at moderate risk, <115 for patients at low risk <80 for patients at very high risk, <100 for patients at high risk, <130 for patients at moderate risk, <145 for patients at low risk High-intensity statins for patients at very high or high risk or Moderate-intensity statins for patients at moderate or low risk Ezetimibe or PCSK9 inhibitors for patients who have not achieved their LDL target or are intolerant to statins or fibrates, niacin, or omega-3 fatty acids for specific indications
CCS <50% reduction in LDL-C from baseline in patients at high risk or <30% reduction in LDL from baseline in patients at intermediate risk <50% reduction in non-HDL-C from baseline in patients at high risk or < 30% reduction in non-HDL from baseline in patients at intermediate risk Moderate- or high-intensity statins for patients at high or intermediate risk, depending on the baseline LDL level and the presence of risk-enhancing factors Ezetimibe or PCSK9 inhibitors for patients who have not achieved their LDL target or are intolerant to statins or fibrates, niacin, or omega-3 fatty acids for specific indications
ACC/AHA <70 for patients with CVD or diabetes or <100 for patients without CVD or diabetes <100 for patients with CVD or diabetes or <130 for patients without CVD or diabetes Moderate-intensity statins for all patients High-intensity statins, ezetimibe, or PCSK9 inhibitors for higher-risk patients or those with risk-enhancing factors

Differential Diagnosis

The differential diagnosis should include the following:

  • Nephrotic syndrome [35]
  • Biliary obstruction
  • Hypothyroidism
  • Pregnancy
  • Drugs (oral estrogens, glucocorticoids, tamoxifen, thiazides)[29]

Prognosis

The prognosis of dyslipidemia depends on several factors, such as the type and severity of the lipid disorder, the presence of other cardiovascular risk factors, adherence to lifestyle modification and pharmacotherapy, and the occurrence of complications. Some types of dyslipidemia are more serious and require more aggressive intervention than others. For example, familial hypercholesterolemia is a genetic form of dyslipidemia that causes very high levels of LDL cholesterol and increases the risk of early and severe cardiovascular events. Patients with this condition need to start pharmacotherapy, usually with statins, ezetimibe, or PCSK9 inhibitors, as early as possible and may also require other treatments, such as apheresis or gene therapy.

Environmental or behavioral factors, such as diet, obesity, physical inactivity, smoking, alcohol consumption, or the use of certain medications, influence other types of dyslipidemia. These types of dyslipidemia are improved by modifying these factors and adopting a healthier lifestyle. Some types of dyslipidemia are associated with other medical conditions, such as diabetes, hypothyroidism, chronic kidney disease, liver disease, or pancreatitis. These types of dyslipidemia are improved by treating the underlying condition and managing complications.[36]

Complications

The most significant complication of dyslipidemia is cardiovascular disease. Complications include sudden cardiac death, acute myocardial infarction, or stroke. Multiple studies have demonstrated that statin and appropriate dyslipidemia treatment has significantly reduced the risk of all-cause mortality, cardiovascular events, and cardiovascular mortality.[37]

Deterrence and Patient Education

As discussed above, patients must recognize and adhere to specific health behaviors that can maintain and lower lipid levels. These include but are not limited to, weight control, which consists of a heart-healthy diet and exercise, as well as avoidance of tobacco. As stated above, patients should also talk with their primary care clinicians about when to start getting screened or initiate treatment. Herbs, red yeast extract, turmeric and curcumin, garlic, and other herbs are some of the natural supplements that may benefit the lipid profile and cardiovascular risk. However, the evidence for their efficacy and safety is inconclusive, and they may interact with some medications or cause adverse effects. 

Enhancing Healthcare Team Outcomes

Enhancing healthcare outcomes for patients with dyslipidemia requires a multidisciplinary treatment team, including cardiologists or endocrinologists, nurses, pharmacists, dietitians, and educators. A multidisciplinary team approach can offer several benefits in managing dyslipidemia, such as improving the diagnosis of lipid conditions like familial hypercholesterolemia, hypertriglyceridemia, and mixed dyslipidemia through appropriate screening and testing methods. Providing individualized and evidence-based treatment plans, including lifestyle modifications and pharmacological interventions, based on the patient’s cardiovascular risk profile, comorbidities, preferences, and goals, is imperative. Enhancing adherence to lipid-lowering therapies and evaluating the outcomes and effectiveness of dyslipidemia management are both essential. Clinicians must know up-to-date guidelines on lipid screening, treatment indications, and LDL level goals. 


Details

Author

Nikos Pappan

Editor:

Anis Rehman

Updated:

3/4/2024 6:34:36 PM

References


[1]

Rader DJ, Hoeg JM, Brewer HB Jr. Quantitation of plasma apolipoproteins in the primary and secondary prevention of coronary artery disease. Annals of internal medicine. 1994 Jun 15:120(12):1012-25     [PubMed PMID: 8185133]


[2]

Berberich AJ, Hegele RA. A Modern Approach to Dyslipidemia. Endocrine reviews. 2022 Jul 13:43(4):611-653. doi: 10.1210/endrev/bnab037. Epub     [PubMed PMID: 34676866]


[3]

Blasco M, Ascaso JF, en representación del grupo de Dislipidemia Aterogénica de la SEA. Control of the overall lipid profile. Clinica e investigacion en arteriosclerosis : publicacion oficial de la Sociedad Espanola de Arteriosclerosis. 2019 Dec:31 Suppl 2():34-41. doi: 10.1016/j.arteri.2019.10.002. Epub 2019 Nov 27     [PubMed PMID: 31785850]


[4]

Hunter PM, Hegele RA. Functional foods and dietary supplements for the management of dyslipidaemia. Nature reviews. Endocrinology. 2017 May:13(5):278-288. doi: 10.1038/nrendo.2016.210. Epub 2017 Jan 30     [PubMed PMID: 28133369]


[5]

Tokgozoglu L, Kayikcioglu M. Familial Hypercholesterolemia: Global Burden and Approaches. Current cardiology reports. 2021 Sep 4:23(10):151. doi: 10.1007/s11886-021-01565-5. Epub 2021 Sep 4     [PubMed PMID: 34480646]


[6]

Goyal A, Cusick AS, Reilly E. Familial Hypertriglyceridemia. StatPearls. 2024 Jan:():     [PubMed PMID: 32310484]


[7]

Writing Group Members, Mozaffarian D, Benjamin EJ, Go AS, Arnett DK, Blaha MJ, Cushman M, Das SR, de Ferranti S, Després JP, Fullerton HJ, Howard VJ, Huffman MD, Isasi CR, Jiménez MC, Judd SE, Kissela BM, Lichtman JH, Lisabeth LD, Liu S, Mackey RH, Magid DJ, McGuire DK, Mohler ER 3rd, Moy CS, Muntner P, Mussolino ME, Nasir K, Neumar RW, Nichol G, Palaniappan L, Pandey DK, Reeves MJ, Rodriguez CJ, Rosamond W, Sorlie PD, Stein J, Towfighi A, Turan TN, Virani SS, Woo D, Yeh RW, Turner MB, American Heart Association Statistics Committee, Stroke Statistics Subcommittee. Heart Disease and Stroke Statistics-2016 Update: A Report From the American Heart Association. Circulation. 2016 Jan 26:133(4):e38-360. doi: 10.1161/CIR.0000000000000350. Epub 2015 Dec 16     [PubMed PMID: 26673558]


[8]

Defesche JC, Gidding SS, Harada-Shiba M, Hegele RA, Santos RD, Wierzbicki AS. Familial hypercholesterolaemia. Nature reviews. Disease primers. 2017 Dec 7:3():17093. doi: 10.1038/nrdp.2017.93. Epub 2017 Dec 7     [PubMed PMID: 29219151]


[9]

Saavedra A, Rodrigues E, Carvalho D. [Dyslipidemia Secondary to Hypothyroidism and Cholestasis]. Acta medica portuguesa. 2020 Mar 2:33(3):204-207. doi: 10.20344/amp.9944. Epub 2020 Mar 2     [PubMed PMID: 32130100]


[10]

Pirillo A, Casula M, Olmastroni E, Norata GD, Catapano AL. Global epidemiology of dyslipidaemias. Nature reviews. Cardiology. 2021 Oct:18(10):689-700. doi: 10.1038/s41569-021-00541-4. Epub 2021 Apr 8     [PubMed PMID: 33833450]


[11]

Mohamed-Yassin MS, Baharudin N, Abdul-Razak S, Ramli AS, Lai NM. Global prevalence of dyslipidaemia in adult populations: a systematic review protocol. BMJ open. 2021 Dec 3:11(12):e049662. doi: 10.1136/bmjopen-2021-049662. Epub 2021 Dec 3     [PubMed PMID: 34862282]

Level 1 (high-level) evidence

[12]

Centers for Disease Control and Prevention (CDC). Vital signs: prevalence, treatment, and control of high levels of low-density lipoprotein cholesterol--United States, 1999-2002 and 2005-200. MMWR. Morbidity and mortality weekly report. 2011 Feb 4:60(4):109-14     [PubMed PMID: 21293326]


[13]

Smith DG. Epidemiology of dyslipidemia and economic burden on the healthcare system. The American journal of managed care. 2007 Jun:13 Suppl 3():S68-71     [PubMed PMID: 17596114]


[14]

Xia Q, Chen Y, Yu Z, Huang Z, Yang Y, Mao A, Qiu W. Prevalence, awareness, treatment, and control of dyslipidemia in Chinese adults: a systematic review and meta-analysis. Frontiers in cardiovascular medicine. 2023:10():1186330. doi: 10.3389/fcvm.2023.1186330. Epub 2023 Jul 5     [PubMed PMID: 37476570]

Level 1 (high-level) evidence

[15]

Zhang T, Chen J, Tang X, Luo Q, Xu D, Yu B. Interaction between adipocytes and high-density lipoprotein:new insights into the mechanism of obesity-induced dyslipidemia and atherosclerosis. Lipids in health and disease. 2019 Dec 16:18(1):223. doi: 10.1186/s12944-019-1170-9. Epub 2019 Dec 16     [PubMed PMID: 31842884]


[16]

Gau GT, Wright RS. Pathophysiology, diagnosis, and management of dyslipidemia. Current problems in cardiology. 2006 Jul:31(7):445-86     [PubMed PMID: 16824902]


[17]

Iqbal J, Al Qarni A, Hawwari A, Alghanem AF, Ahmed G. Metabolic Syndrome, Dyslipidemia and Regulation of Lipoprotein Metabolism. Current diabetes reviews. 2018:14(5):427-433. doi: 10.2174/1573399813666170705161039. Epub     [PubMed PMID: 28677496]


[18]

Lugo-Somolinos A, Sánchez JE. Xanthomas: a marker for hyperlipidemias. Boletin de la Asociacion Medica de Puerto Rico. 2003 Jul-Aug:95(4):12-6     [PubMed PMID: 15032023]


[19]

Karantas ID, Okur ME, Okur NÜ, Siafaka PI. Dyslipidemia Management in 2020: An Update on Diagnosis and Therapeutic Perspectives. Endocrine, metabolic & immune disorders drug targets. 2021:21(5):815-834. doi: 10.2174/1871530320666200810144004. Epub     [PubMed PMID: 32778041]

Level 3 (low-level) evidence

[20]

Kopin L, Lowenstein C. Dyslipidemia. Annals of internal medicine. 2017 Dec 5:167(11):ITC81-ITC96. doi: 10.7326/AITC201712050. Epub     [PubMed PMID: 29204622]


[21]

Burlutskaya AV, Tril VE, Polischuk LV, Pokrovskii VM. Dyslipidemia in pediatrician's practice. Reviews in cardiovascular medicine. 2021 Sep 24:22(3):817-834. doi: 10.31083/j.rcm2203088. Epub     [PubMed PMID: 34565080]


[22]

Fredrickson DS. An international classification of hyperlipidemias and hyperlipoproteinemias. Annals of internal medicine. 1971 Sep:75(3):471-2     [PubMed PMID: 5568160]


[23]

Kirkpatrick CF, Sikand G, Petersen KS, Anderson CAM, Aspry KE, Bolick JP, Kris-Etherton PM, Maki KC. Nutrition interventions for adults with dyslipidemia: A Clinical Perspective from the National Lipid Association. Journal of clinical lipidology. 2023 Jul-Aug:17(4):428-451. doi: 10.1016/j.jacl.2023.05.099. Epub 2023 Jun 2     [PubMed PMID: 37271600]

Level 3 (low-level) evidence

[24]

Wang Y, Xu D. Effects of aerobic exercise on lipids and lipoproteins. Lipids in health and disease. 2017 Jul 5:16(1):132. doi: 10.1186/s12944-017-0515-5. Epub 2017 Jul 5     [PubMed PMID: 28679436]


[25]

Cicero AFG, Landolfo M, Ventura F, Borghi C. Current pharmacotherapeutic options for primary dyslipidemia in adults. Expert opinion on pharmacotherapy. 2019 Jul:20(10):1277-1288. doi: 10.1080/14656566.2019.1604687. Epub 2019 May 6     [PubMed PMID: 31059312]

Level 3 (low-level) evidence

[26]

Chang Y, Robidoux J. Dyslipidemia management update. Current opinion in pharmacology. 2017 Apr:33():47-55. doi: 10.1016/j.coph.2017.04.005. Epub 2017 May 17     [PubMed PMID: 28527325]

Level 3 (low-level) evidence

[27]

Nishikido T, Ray KK. Inclisiran for the treatment of dyslipidemia. Expert opinion on investigational drugs. 2018 Mar:27(3):287-294. doi: 10.1080/13543784.2018.1442435. Epub 2018 Feb 22     [PubMed PMID: 29451410]

Level 3 (low-level) evidence

[28]

Eckel RH, Jakicic JM, Ard JD, de Jesus JM, Houston Miller N, Hubbard VS, Lee IM, Lichtenstein AH, Loria CM, Millen BE, Nonas CA, Sacks FM, Smith SC Jr, Svetkey LP, Wadden TA, Yanovski SZ, American College of Cardiology/American Heart Association Task Force on Practice Guidelines. 2013 AHA/ACC guideline on lifestyle management to reduce cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Journal of the American College of Cardiology. 2014 Jul 1:63(25 Pt B):2960-84. doi: 10.1016/j.jacc.2013.11.003. Epub 2013 Nov 12     [PubMed PMID: 24239922]

Level 1 (high-level) evidence

[29]

Stone NJ, Robinson JG, Lichtenstein AH, Bairey Merz CN, Blum CB, Eckel RH, Goldberg AC, Gordon D, Levy D, Lloyd-Jones DM, McBride P, Schwartz JS, Shero ST, Smith SC Jr, Watson K, Wilson PW, American College of Cardiology/American Heart Association Task Force on Practice Guidelines. 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Journal of the American College of Cardiology. 2014 Jul 1:63(25 Pt B):2889-934. doi: 10.1016/j.jacc.2013.11.002. Epub 2013 Nov 12     [PubMed PMID: 24239923]

Level 1 (high-level) evidence

[30]

Vavlukis M, Vavlukis A. Adding ezetimibe to statin therapy: latest evidence and clinical implications. Drugs in context. 2018:7():212534. doi: 10.7573/dic.212534. Epub 2018 Jul 9     [PubMed PMID: 30023003]


[31]

Karr S. Epidemiology and management of hyperlipidemia. The American journal of managed care. 2017 Jun:23(9 Suppl):S139-S148     [PubMed PMID: 28978219]


[32]

Mills EJ, O'Regan C, Eyawo O, Wu P, Mills F, Berwanger O, Briel M. Intensive statin therapy compared with moderate dosing for prevention of cardiovascular events: a meta-analysis of }40 000 patients. European heart journal. 2011 Jun:32(11):1409-15. doi: 10.1093/eurheartj/ehr035. Epub 2011 Mar 8     [PubMed PMID: 21385791]

Level 1 (high-level) evidence

[33]

Ray KK, Bays HE, Catapano AL, Lalwani ND, Bloedon LT, Sterling LR, Robinson PL, Ballantyne CM, CLEAR Harmony Trial. Safety and Efficacy of Bempedoic Acid to Reduce LDL Cholesterol. The New England journal of medicine. 2019 Mar 14:380(11):1022-1032. doi: 10.1056/NEJMoa1803917. Epub     [PubMed PMID: 30865796]


[34]

European Association for Cardiovascular Prevention & Rehabilitation, Reiner Z, Catapano AL, De Backer G, Graham I, Taskinen MR, Wiklund O, Agewall S, Alegria E, Chapman MJ, Durrington P, Erdine S, Halcox J, Hobbs R, Kjekshus J, Filardi PP, Riccardi G, Storey RF, Wood D, ESC Committee for Practice Guidelines (CPG) 2008-2010 and 2010-2012 Committees. ESC/EAS Guidelines for the management of dyslipidaemias: the Task Force for the management of dyslipidaemias of the European Society of Cardiology (ESC) and the European Atherosclerosis Society (EAS). European heart journal. 2011 Jul:32(14):1769-818. doi: 10.1093/eurheartj/ehr158. Epub 2011 Jun 28     [PubMed PMID: 21712404]

Level 1 (high-level) evidence

[35]

Politano SA, Colbert GB, Hamiduzzaman N. Nephrotic Syndrome. Primary care. 2020 Dec:47(4):597-613. doi: 10.1016/j.pop.2020.08.002. Epub 2020 Sep 26     [PubMed PMID: 33121631]


[36]

Muntner P, Colantonio LD, Cushman M, Goff DC Jr, Howard G, Howard VJ, Kissela B, Levitan EB, Lloyd-Jones DM, Safford MM. Validation of the atherosclerotic cardiovascular disease Pooled Cohort risk equations. JAMA. 2014 Apr 9:311(14):1406-15. doi: 10.1001/jama.2014.2630. Epub     [PubMed PMID: 24682252]

Level 1 (high-level) evidence

[37]

Chou R, Dana T, Blazina I, Daeges M, Jeanne TL. Statins for Prevention of Cardiovascular Disease in Adults: Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA. 2016 Nov 15:316(19):2008-2024. doi: 10.1001/jama.2015.15629. Epub     [PubMed PMID: 27838722]

Level 1 (high-level) evidence