The Epidemiology and History of Cardiovascular Disease

First post for PHAR3303! This is basically a "background information" type lecture- or at least I hope it is because I'll admit that I didn't pay close attention to all of the details :P

Be able to define the term "epidemiology" and appreciate its value in studying causes of human disease on a population scale

"Epidemiology" is the study of health and disease in populations, as opposed to just studying the mechanisms of disease in some cells, organs or individuals. It is useful in letting us know the prevalence of a disease, as well as in coming up with approaches to tackle them on a wider scale (e.g. policy measures to combat tobacco consumption).

Identify the major types of cardiovascular disease (CVD), and demonstrate awareness for how epidemiological approaches help us address the toll CVD takes on the health of human societies

Many cardiovascular diseases occur due to atherosclerosis. These include ischaemic heart disease, coronary artery disease, cerebrovascular disease, hypertension and peripheral vascular disease. Other heart diseases include congenital heart disease, rheumatic heart disease, cardiomyopathies and arrhythmias. If you want more details, I wrote a few posts on cardiovascular diseases for PHGY350 (a unit I took while on exchange).

Be able to describe the significance and contributions large scale multi-generational, community-based observational studies such as the Framingham Study have made to our ability to diagnose, treat and prevent CVD

Following the death of President Roosevelt from a cerebral haemorrhage related to high blood pressure, there was increased interest in risk factors for CVD. A long-term cohort study, called the Framingham Study (after the town that the original cohort came from), was conducted. The large number of participants and the length of time of the study allowed researchers to identify many different risk factors for CVD, such as hypertension, diabetes and so on. This is knowledge that we take for granted now, but in the past it did help dispel many myths, as well as open up new therapeutic approaches (e.g. working to lower blood pressure).

Identify the major insights that have emerged from descriptive, analytical and interventional studies of CVD

Descriptive epidemiology describes the distribution of cardiovascular disease in terms of characteristics such as age, gender, place and so on. Some of the major insights from descriptive epidemiology studies of CVD include the following:

• Global distribution patterns: CVD accounts for ~1/3 of global deaths, but the majority of these deaths take place in low- and middle-income countries (due to less access to medical care, less expenditure on public health campaigns and so on).
• Age: The percentage of deaths attributable to CVD increases as age increases.
• Sex: Contrary to popular belief, CVD affects nearly as many women as men, though usually women are affected at an older age. There are also sex-specific risk factors for CVD, such as oral contraceptives, hormone replacement therapy and so on.
• Global changes in CVD mortality: In many developed countries, CVD deaths have declined due to increased awareness of risk factors and improved medical care. However, in many developing countries, there are opposing trends due to increased longevity, as well as the wider availability of fatty foods etc.

Analytic epidemiology examines risk factors for CVD. Many risk factors have been identified, but only a handful are attributed to the majority of cases. Some of these risk factors are modifiable, such as obesity, physical inactivity and tobacco use, whereas others are not modifiable such as age or ethnicity.

Experimental epidemiology looks at interventions that can be used to prevent CVD. There are several different levels of prevention:

• Primordial prevention tends to look at legal and other widespread interventions. An example of primordial prevention would be banning smoking in many public areas so as to prevent CVD, lung cancer and other issues.
• Primary prevention also involves widespread interventions (though maybe less widespread than the legal interventions in primordial prevention). These interventions include health education programs, sports programs, regular blood pressure checks, and so on.
• Secondary prevention involves taking care of patients who are showing some symptoms of CVD. Screening and treatment of these patients are done.
• Tertiary prevention involves taking care of patients who have already had a heart attack or some other complication of CVD. The aim of tertiary prevention is to prevent recurrence of such events.