Epidemiology, Chp. 2 - Practical Applications of Epidemiology

Changes in disease frequency over time. They're used in historical use of epidemiology health and illness.

1. Aging of the general population: because of improved medical care, the impact of mortality from diseases reduces. There may be greater uncertainty about the precise cause of death.

2. Changes in diagnostic criteria/reporting: criteria changes over time due to increased knowledge about a disease, some categories of diseases used earlier in time may be omitted altogether.

3. Changes in disease treatment and cure: disappearing disorders, residual disorders, persisting disorders, new epidemics.

4. Changes in population dynamics (migration): a) births, b) deaths, c) migration. When these factors don't contribute to net increases or decreases, the population is in equilibrium.

Fixed population: adds no new members --> decreases in size due to only having deaths.

Dynamic population: adds new members through migration and births or loses through emigration or death.

Steady population: in a steady state when the number of members exiting equals the number entering.

In a community that has primarily elderly, health problems related to aging would tend to predominate. Because of the longer life expectancy of women, an older population would tend to have a majority of elderly women, who might have unique health needs. Point is, age and sex of the population have specific needs that the community will need to cater to create a healthy one.

People who have inadequate income and job opportunities lack health insurance and access to health care. This also includes people who have low educational attainment, meaning the population will be less aware of dietary and exercise practices that promote health.

Some health outcomes are just more common in one racial or ethnic group. Ex. diabetes and latinos and sickle cell anemia and african americans. Members of some religions may adopt specific lifestyles. Ex. abstaining from alcohol.

To eliminate health disparities among segments of the population, including differences that occur by gender, race or ethnicity or income.

Differences in health outcomes that are closely linked with social, economic and environmental disadvantage.

True; p. 228.

True; p. 240.

Showing the relationship and identifying the etiologic (causal) associations between an exposure and an outcome.

An event, condition or characteristic that preceded the disease and without the disease event either wouldn't have occurred or wouldn't have occurred until some other time.

1. The agent is always found in every case of the disease.

2.The organism is not with any other disease; one agent-one disease.

3. The organism isolated from someone who has the disease, and cultured through several generations produces the disease in a healthy animal.

The stronger the association, the more likely of a causal relationship. It's less likely to be the result of errors.

False; weak associations do not disprove causation.

This refers to whether the association between an agent and health effect has been observed by different persons, in different places, circumstances and times.

The causal factor should lead to only one disease and that the disease should result from this single cause. However, lack of specificity is not reason to refute causation.

The exposure to the causal factor must precede the onset of disease. This can be hard to prove.

This shows an evidence of a dose-response curve. Meaning that an increase in level, intensity and duration to an agent leads to progressive increases in risk.

The association needs to be plausible with known biological facts about the disease (e.g. chemicals in cigarettes harm lung tissue). Common sense and known biology must take precedence over statistical relationships.

The association must no seriously conflict with what's already known about the natural history and biology of the disease.

Experiment has to be randomized as it's the only way that can claim causality.

That if one agent can cause "outcome X", so might others. Not as strong as the other criteria.

True.

A risk factor is an exposure that is associated with a disease or health outcome.

- case control

- cohort study

Design that compares persons with a disease (cases) against those without it (controls). This is an observational study.

Design where a group of people free from a disease is assembled according to a variety of exposure that are hypothesized to increase/decrease the chance of getting a disease.