• Overview
• Definition
• Incidence, prevalence and trends
• Risk factors
• Health consequences
• Costs
• Contributors

Risk Factors

Risk factors for cardiovascular disease (CVD) can be fixed, such as age and male sex, or modifiable, such as smoking or diet.

The InterHEART study recently reported that nine factors explain over 90% of heart attacks including smoking, lipids, hypertension, diabetes, obesity, diet, physical activity, alcohol consumption, and psychosocial factors. ¹ Total cholesterol, blood pressure and smoking together explain 80-90% of coronary heart disease in the UK. Although epidemiologists and geneticists are researching new factors, (such as homocysteine, CRP, ACE gene expression etc), these are unlikely to be considered “major” risk factors. ^{2 3}

Fixed risk factors for cardiovascular diseases

Age

Mortality, incidence, and prevalence rates all increase steeply with age, approximately doubling with each decade. CVD is thus increasingly common above the age of 60 and rare below age 30.

Male sex

Men tend to get coronary heart disease (CHD) about ten years younger than women.

Modifiable risk factors for cardiovascular diseases

Cholesterol and dietary saturated fats

Cholesterol is the most powerful and important risk factor for CHD and other forms of atherothrombotic CVD. Cholesterol is necessary for CHD, but not sufficient. ⁴ CHD risk increases logarithmically from about 3.5mmol/l total cholesterol. ⁵ Almost everyone in the UK therefore has a higher than ideal level of total cholesterol. Target levels of “5.0mmol/l”, are thus relatively arbitrary. ⁶ Total cholesterol is made up of lipid sub-fractions: about two-thirds LDL (low density lipoproteins), one-fifth HDL (high density lipoprotein) and one-sixth triglycerides. CHD risk is increased by higher LDL levels, but reduced by higher levels of (protective) HDL.

Total cholesterol levels less than 4 mmol/l were seen in some nomadic and pastoral communities, including rural populations eating a traditional Chinese diet. ⁷ Levels rise, however, with Westernisation of diet and increased consumption of saturated fatty acids. Conversely, vegetable fats and oils and fish provide mono- and polyunsaturated fatty acids which lower total cholesterol and LDL, and increase the HDL/LDL ratio. ^{8 9}

Blood pressure and dietary salt

Coronary heart disease risk increases logarithmically from a diastolic blood pressure of about 70mmHg, systolic blood pressure of about 115 mmHg. Almost everyone in the UK therefore has a higher than ideal level of blood pressure (defining “hypertension” as a blood pressure above 140/95 or 120/80 mmHg is thus relatively arbitrary).

Blood pressure in populations reflects average dietary intake of salt. In traditional communities who consume little salt, low blood pressure remains the norm into old age. Conversely, blood pressure rises with age in all industrialised populations. Furthermore, short term and long term reduction in dietary salt intake reduces blood pressure in individual subjects. ¹⁰ Blood pressure is also increased by dietary saturated fats, but decreased by sustained weight loss or regular physical activity.

Smoking

Compared with non-smokers, CHD rates are about five times higher in young adult smokers, about twice as high in older smokers. This increased CHD risk halves within a year of quitting and becomes minimal after a decade. ^{11 12}

Smoking is also a major risk factor for stroke, and even more so for peripheral vascular disease (PVD).

Diabetes (and glucose intolerance)

About 80% of people with diabetes die from CHD. It is 2-3 times higher in people with diabetes, and increases with the duration of the disease. CVD risk also increases with pre-diabetes/glucose intolerance or insulin resistance. The risk of type 2 diabetes is greatly increased by obesity.

Obesity

Obesity causes most of its cardiovascular damage via increased blood pressure, increased cholesterol and diabetes/glucose intolerance. Today’s UK environment is “obesogenic”, with commercial and social forces marketing bounteous sources of cheap saturated fat; all made worse by multiple barriers to routine physical activity. ¹³

Physical inactivity

The UK environment promotes sedentary lifestyles and generates many barriers to routine activities like walking or cycling. CHD rates are about twice as high in sedentary groups as in those who are physically active. Sedentary people also tend to smoke more and have higher blood pressure, cholesterol, and weight. However, successfully changing from a sedentary to a long term active lifestyle can reduce CHD risk by about 30%. ¹³

Risk factors for hemorrhagic stroke & PVD

Hemorrhagic stroke rates principally reflect levels of blood pressure (systolic more than diastolic). PVD reflects the major CVD risk factors, especially smoking.