Deck 2: Principles of Epidemiology 

Question 1

Define epidemiology and its relationship to community nutrition. What is meant by the terms distribution and determinants

Answer 1

The branch of medicine that deals with the causes, distribution, and control of disease in a population is called epidemiology. The word epidemiology is derived from Greek language where " epi " means on or upon, " demos "- people, and " logos "- the study of. Thus, the epidemiology is the study upon people. The person who studies about the transmission and control of epidemic diseases is called epidemiologist.
Epidemiology is also defined as the study of the distribution and determinants of disease frequency in man.
Epidemiology is helpful in developing the methodology that is used in clinical research, public health studies, and basic research in biological sciences.
Epidemiology has a specific relationship with community nutrition. Nutritional epidemiology is a part of epidemiology that involves research about role of nutrition in developing the disease and monitors nutritional status of a population. Thus, based on the nutritional problems of a community it develops and evaluates interventions to achieve and maintain healthy eating patterns in a community.
Hence, epidemiology has relationship with community nutrition in preventing the occurrence nutritional deficiency disorders.
The word "distribution" is concerned with the frequency and pattern of events that occur in a population. The word frequency indicates both rate and number of events in a population, while pattern indicates occurrence of health-related events. The pattern is based on three characteristics, which includes time (annual, seasonal, daily, or hourly occurrence of a disease), place (urban-rural, schools, etc.), and personal (age, sex, race, etc.) characteristics.
The word " determinants" is to search for causes and other factors that influence the occurrence of health-related events such as diseases, syndromes, and injuries.

Question 2

Consider the agent, host factors, and environment as contributors to heart disease. Provide an example of a factor to represent each of these, and list an intervention strategy to mitigate risk associated with the factor.

Answer 2

The processing of body and elimination of its waste from the body are very important to prevent the patient from drug toxicity. The main organs that need to be function properly to prevent drug toxicity are liver, kidneys, heart, lungs, digestive system, and glands.
The heart is a muscular organ that is involved in pumping of blood through blood vessels. The heart is surrounded by a two layers of protective sac called pericardium. The pericardium contains a fluid called pericardial fluid.
The normal resting state heart rate ranges between 60 to 100 times per minute. The heart arrest is considered to be physical death of an individual.
The heart diseases are also called cardiovascular diseases. Most of the cardiovascular diseases are non-communicable and are caused due to different factors such as lifestyle, etc. The different diseases include heart failure, cardiomyopathy, coronary artery disease, and heart murmurs.
The likelihood of a person to acquire the disease due to exposure to certain factors is called risk factors.
The different factors associated with coronary heart disease (CHD) are as follows:
• Physical inactivity or sedentary lifestyle
• Obesity
• Intake of high low density lipoproteins (LDL) cholesterol
• Cigarette smoking
• Hypertension
• Diabetes
• Stress
The major agents that contribute to CHD are Chlamydia pneumoniae and Helicobacter pylori.
The host factors that contribute to CHDs are obesity, high blood pressure, high cholesterol levels, smoking, and inactive lifestyle etc.
Environment is the condition in which an individual live such as household, town, and larger communities. It also includes social environment that includes norms and behaviors of families, friends, and others in the community. The environmental factors are not specific for an individual and have similar effect on each and every individual living in a community.
The environmental risk factors that contribute to the CHDs include unhealthy food habits, poor access to appropriate health care, and sedentary lifestyle.
The high intake cholesterol results in heart disease. The cholesterol builds up in the walls of arteries and causes atherosclerosis where the arteries become narrowed and blood flow to the heart decreases or blocked. LDL is the main source of clogging plaque in the arteries.
The obesity and sedentary lifestyle are also associated with CHDs. The other risk factors associated with CHDs are diabetes, hypertension and hypercholesterolemia. The obesity often results in diabetes, hypertension and hypercholesterolemia. The sedentary lifestyle also results in increased blood pressure.

Question 3

Explain hypothesis testing and how data about disease processes are obtained using the epidemiological method.

Answer 3

A hypothesis is a proposed explanation for a phenomenon. In epidemiological studies, the investigator identifies a cause-effect comparison to be tested as the research hypothesis. After formulating the research hypothesis, a study is designed by the investigator to obtain information which provides him with inferences or interpretations. Experimentation is done to collect relevant data; results are analyzed to see if they prove the hypothesis or disprove it.
Epidemiological study collects data initially about individuals, specific agents, and outcomes. The data is then processed to arrange it in a specific way; statistical analyses are done to investigate statistical associations among various groups which may suggest a cause-effect relationship. The cause is then studied again to confirm its effect on the population.

Question 4

Explain how the complexity of our diets creates challenges in studying the relationship of diet to disease.

Question 5

Explain why the day-to-day variation in an individual's nutrient intake can have important implications for nutritional epidemiologic studies.

Question 6

Differentiate among the different types of nutritional epidemiological studies.