Epidemiology Flashcards
What is epidemiology?
The study of the distribution and determinants of disease and health in specific populations in order to understand and improve health
Compare and contrast descriptive vs. analytic epidemiology
Descriptive epidemiology is the use of distribution to describe patterns or trends of diseases in populations
Analytic epidemiology is the method that uses determinants to measure the causes or etiology of diseases.
Describe surveillance
An ongoing systematic collection, analysis and interpretation of health data by portraying ongoing patterns of disease and occurrence to help guide public health decision making & action.
It usually involves the systematic collection of mortality and morbidity reports & the dissemination as well as interpretation of these
What are the applications of epidemiology?
In public health: when high risk groups are identified, public health will determine prevention strategies (primary and secondary)
In Clinical Practice: observational studies of epidemiology (John Snow’s method, cross-sectional, case-control and cohort studies) are used to
- diagnose and;
- choose appropriate treatment
In Disease Management: figures out how to deliver integrated care to patients & REDUCE COSTS
What is the “distribution” that epidemiology studies?
Distribution refers to the people (who), place (where), time (when) [patterns] and frequency (number of health events and cases) within or between a defined population
Why is epidemiology often described as the “basic science of public health”?
How is distribution measured?
Distribution is measured by describing patterns and trends of health events using 5 W’s:
- Who (person/race/ethnicity)
- Where (location/place)
- When (time/frequency)
- What (diagnosis/health event)
- Why (causes, risk factors and modes of transmission)
Explain how epidemiology may be applied in measuring the distribution of TB?
Who (There has been a decline in the incidences of Tuberculosis in ALL races; Asians have the highest incidence rate among all)
Where (Canada)
When (in 1996, incidences of TB was the highest but has been declining ever since; Native Americans have shown more incidences since 2006)
- Frequency (Canada has had an average of 265.8 cases per 100, 000 people)
Contrast: sporadic vs. endemic vs. epidemic vs. pandemic
Sporadic disease has the fewest number of cases over time
Endemic: a disease that regularly occurs within a community or particular location/geographic area
Epidemic: widespread condition from a common etiology (set of causes or the cause) affecting a large or wide population/area
Pandemic: epidemic that becomes more widespread and affects a larger proportion of the population (country or the entire world)
What are determinants?
The causes or factors that influence the disease’s occurrence
Contrast risk vs risk factor
Risk is the probability that an event will occur while risk factors are exposures typically associated with an outcome
What are examples of risk factors?
Disease
Adverse health event
Mortality
Quality of life (poor housing, poor diet, lack physical activity)
“Why” are persons suffering with tetanus?
Older populations (60 years old and over) have the highest incidences of tetanus. Therefore, age is the cause or determinant of being diagnosed with tetanus.
Define disease vs health:
Disease or health-related state and event is anything that affects the wellbeing of a population like endemic communicable diseases, non-communicable infectious diseases and behaviours (poor diet or seat belt usage)
Health is the absence of disease
What are “specific populations” in epidemiology?
Action of epidemiologists is directed at the health of an entire population or subpopulation.
What do epidemiologists need to understand in order to facilitate control of the disease spread?
Health of specific populations (who, when and where)
What is an example of “specified population” that is related to cancer?
“30 people developed Leukemia”
Describe the sequence of epidemiological investigations:
- Suspect that a certain exposure influences the occurrence of a particular disease
- Form a hypothesis about the exposure-disease association
- Measure the exposure-disease association by conducting epidemiological studies
- Determine (judge) if the association is valid and causal (whether or not the exposure is a cause of the outcome)
- Evaluate preventions & treatment
What is the major epidemiologic milestone for cholera?
In the 19th century, it was found that contaminated water (exposure) is associated with an increase in the incidences of cholera cases
What is the major epidemiologic milestone for TB?
It was found that streptomycin (an antibiotic and exposure) is associated with a decrease in the incidences of TB cases
What is the major epidemiologic milestone for Toxic Shock Syndrome?
It was found that tampon use (exposure) is associated with more incidences of Toxic Shock syndrome
What is the major epidemiologic milestone for Pellagra?
It was found that niacin (B3) deficiency (exposure) is associated with more incidences of Pellagra
What is the major epidemiologic milestone for lead?
In the 21st century, it was found that lead (exposure) is associated with a decrease in children’s IQ
Explain the aim of epidemiology using an example?
Epidemiology aims at identifying and understanding the causes of disease.
For example, smoking (exposure) is associated with lung cancer (disease) which will affect the population’s quality of life (outcome)
What are the objectives of epidemiology?
- Identify risk factors
- Determine the extent of the disease in the community
- Study the disease’s natural history
- Evaluate methods of healthcare delivery and;
- Create public policies
State the elements/aims of descriptive epidemiology.
- Describes the frequency and distribution of risk factors in populations
- Allows us to assess the extent of the disease
- Helps us to develop hypothesis of etiologic or cause-related research
A graph showing the percentage distribution of estimated new cases and deaths for selected cancers in males in Canada (2010) is an example of which type of epidemiology? Why?
This is descriptive epidemiology because it describes the frequency of new cases for males (who) with cancer (exposure) in Canada (where) in 2010 (time/when).
What did John Snow observe that would change the way we view diseases and how they propogate?
John Snow observed that cases of cholera were in concentrated clusters around a water pump on Broad Street
Why is John Snow regarded as the “father of epidemiology”?
He created an approach of assessing disease through patterns and environmental factors.
What did Snow recognize was an essential part of treating diseases effectively?
Snow realized that it is also important to see patients as the community/population or a part of their larger environment.
How was surveillance applied in analyzing “childbed fever” or puerperal fever, a major cause of mortality in mothers during childbirth?
Vienna Hospital had two obstetrics clinics:
One had physicians and med students performing autopsies;
the other clinic did not involve midwives performing autopsies
What mortality rates were observed in the obstetric clinic for childbed fever or puerperal fever?
The second clinic (midwives not performing autopsies on the deceased women) had lower mortality rates
What were the study’s questions for childbed fever?
Was the disease-carrying organisms being transmitted from dead women being autopsied to live expectant women?
&
Was this the reason for the higher number of cases of childbed fever in Clinic 1?
How did Dr. Ignaz Semmelweis experimentally intervene in the study/surveillance of mortality from childbed fever?
Dr. Ignaz Semmelweis got the physicians and med students to wash their hands and under their nails after autopsy & before observing the expectant women
What did Dr. Ignaz Semmelweis find after his experimental intervention?
Dr. Ignaz Semmelweis found that a culture of Streptococcus pyogenes were present in a large number BEFORE HANDWASHING. The population of this bacterial culture became lesser after washing hands & nonexistent after an ALCOHOL WASH.
What other findings, similar to Dr. Ignaz Semmelweis, were initially rejected and then accepted years later?
HPV —> cervical cancer
Helicobacter pylori —-> stomach cancer
What is important for surveillance measures and what do these indicate?
- Indicates associations between exposure and disease
- Analysis of ongoing PATTERNS in IMPORTANT
Contrast passive vs active surveillance
Health department passively receives reports of suspected illness or exposure-disease associations
A staff dedicated to pursuing identification of cases
What is the cycle of surveillance?
- Collect data
- Integration
- Analysis + interpretation
- Surveillance products produced
- Dissemination to all who “need” to know
Which diseases are on the Canadian Chronic Disease Surveillance System?
Cardiovascular;
Diabetes;
Chronic respiratory;
Mental illnesses;
Musculoskeletal and;
neurological conditions
What was the message of Hans Rosling in the video, “200 Countries, 200 years, 4 minutes - The Joy of Stats”?
Hans Rosling was communicating that the countries have converged and emerged to increasingly healthier and wealthier nations as industrialization boomed.
Major health events (World Wars and Spanish Flu) contributed to some sudden falls and fluctuations in the lifespan of populations.
Economic challenges also affected the health of many nations.
What type of scientific evidence is strongest vs weakest on the hierarchy of scientific evidence?
Meta-analyses and systematic/peer reviews are strongest
Case reports, opinions and letters are weakest
Describe why cross sectional, case-control, cohort studies and randomized trials are in order of weakest to strongest on the hierarchy of scientific evidence?
Cross-sectional studies view and determine the exposure and outcome at once at a certain time (quick overview of the population)
Case-control studies look at determining if the cases and controls are exposed or not
Cohort studies select participants with or without exposure and OVER TIME determine whether these participants develop the disease
Randomized trials assign participants to INTERVENTION & CONTROL groups to determine whether these groups develop the OUTCOME or not.
What is an example of disease management?
Caring for multiple patients with related or unrelated chronic conditions (chronic illness are usually expensive to treat)
