2 factors causing emergence of new epidemics
- prescribing too many antibiotics --> diseases mutate a lot, so we have to keep coming up with new medicines for it
- environmental changes --> flooding, changing weather patterns
Who is John Snow? What was he known for?
- father of epidemiology
- british cholera epidemic - inspected water pumps to see what was causing the disease
Outbreak Investigations (6 steps)
- 1. establish case definition - specific set of people that fit the disease
- 2. confirm suspected cases - asking questions related to case and try to figure out a reason for disease
- 3. define population denominator - limit it to people within a radius
- 4. review the literature - read about stuff relating to case
- 5. exposure assessment - make sure affected people were contaminated b/c of possible site and not other sites
- 6. generate plausible hypothesis
Incidence vs. Prevalence
- incidence = number of new cases / total population
- prevalence = number of all cases / total population
What does prevalence NOT include?
doesn't count all the people who already died
Prospective Studies vs. Retrospective Studies
- prospective - begins at beginning and follows people over time
- retrospective - begins today, look backwards to see what happened to people in the past
The two types of epi studies?
- descriptive studies --> describes the occurrence of the outcome, examining distribution of disease and observing basic features
- analytic studies --> describes association between exposure and outcome, tests hypothesis about cause by studying how exposure relates to disease
3 types of descriptive studies?
- case report studies - unusual findings
- case series - multiple cases of findings
- description epidemiology studies - population based cases with denominator, look at entire population that are exposed
2 types of analytic studies
3 types of observational analytic studies?
- case control studies --> determines and compares exposures, not outcomes
- cohort studies --> compares incidence of outcome to see if exposure leads to the outcome (all have been exposed but you observe which ones get affected)
- cross-sectional studies --> aka prevalence study, single period of observation (today), exposure and disease info is collected at the same time
- randomized control trial studies --> planned experiment with group of people, 2 groups (1 is the control), designed to test how effective the intervention/clinical treatment is, completely randomized
Triad for descriptive studies
Triad for analytic studies
- host - person that is affected
- agent - factor that is essential for transmittance of disease
- environment - factor that affects the agent
ability of a test to correctly identify those who have the disease
- the ability of a test to correctly identify those who do not have the disease
High sensitivity = ?
few false negatives
High specificity = ?
few false positives
When is it better to have test of specificity vs. test of sensitivity?
- specificity - better to test if the treatment is harmful (chemo for cancer)
- sensitivity - better to have this test when you need to detect something early on (cancer)
Problems with sensitivity and specificity? Sometimes so good that ___?
- specificity - sometimes so good at finding negatives that it gives false negatives
- sensitivity - sometimes so good at finding positives that it gives false positives
true positive / (true positive + false negative)
true negative / (true negative + false positive)
test indicates disease but there is actually no disease present
test indicated no disease there actually is a disease
4 Key features of health statistics
- population based - usually a small sample of overall population
- measure wide range of health indicators for a community (entire country or state or county)
- collected/analyzed over a period of time (months, years, etc)
- include different types of data - vital, morbidity, mortality, use & cost of health care
Assessing quality of health data (5 things)
- nature (source) of data
- availability of data
- validity and reliability of measures
- completeness of population coverage
- strengths & limitations of study design
what do health statistics provide?
key indicators about life and health in a particular region
Reliability vs. Validity of data
- reliability - consistent, meaning it is collected in the same way over multiple years
- validity - accuracy
A reliable measure is usually free from ____
measurement error or bias
Scale is valid if _______
if it measures what it intends to measure without systematic error
Completeness of the data
representative of entire parent population
network effect, one person can go out and recruit other similar people
Generalizability (external validity)
ability to apply findings to a people that did not participate in a study
care it take to identify all cases of a given disease
How to find health statistics? (4 steps)
- formulate the question
- choose the best resources for the question
- evaluate the results
- repeat as necessary
What are the two types of diseases?
- Infectious (communicable)
- Chronic (non-communicable)
What are infectious diseases?
- communicable diseases
- caused by pathogenic microorganisms (bacteria, viruses, parasites, fungi)
- can be spread directly or indirectly
What are the 2 types of infectious diseases?
- emerging - newly identified, previously unknown infectious agents that cause public health problems either locally or internationally
- re-emerging - known for some time, fell to low levels, and now showing upward trends in incidence or prevalence worldwide
What is a chronic disease?
- not passed from person to person
- of long duration and generally slow progression
4 main types of chronic diseases?
- cardiovascular --> diseases of blood vessels of the heart (stroke, heart disease)
- cancers --> severe health consequences, generally not very treatable
- chronic respiratory diseases
- diabetes --> increased blood sugar levels
Causes and 2 types of diabetes? & a third type?
- due to a lack of insulting or an inability or body's tissues to respond properly to insulin
- type 1 --> need for lifelong insulin therapy
- type 2 --> related to insulin resistance, managed with diet and exercise
- gestational diabetes --> develops during pregnancy
disease vs. illness
- disease - pathological changes within the body which are expressed in various physical signs and symptoms (symptoms during pregnancy)
- illness - an individual's subjective interpretation and response to these signs and symptoms (ancestor coming & possessing body)
What is culture?
a system of thoughts and behaviors shared by a group of people
- orientation to space & time
- social organization
- family structure
- gender roles
- social factors
- stigmatization of illness
- where sufferers claim to have a specific disease that many physicians don't recognize or acknowledge as medical
- ex: chronic fatigue
- when human problems or experiences become defined as medical problems
- ex: madness, drug & alcohol problems, menopause, baldness
What is a social construction?
- a conceptual frame work that emphasizes the cultural and historical aspects of phenomena widely thought to be exclusively natural
- examines how individuals and policy groups contribute to producing perceived social reality and knowledge
Long term trends in socioeconomic status & health
- better sanitation, clean water, etc
- diseases of affluence (CHD, stroke, obesity)
- disease patterns are changing
Inequity vs. inequality
- inequity - unfair or unjust
- inequality - unequal
Fixed vs. fluid factors in health
- fixed --> things that cannot be changed, genetic or biological differences
- fluid --> things that can change and we don't have control over (age, income, where you live)
What is social epidemiology?
studies the social distribution and social determinants of health based on things like socioeconomic states, gender & ethnicity
Problem with social epidemiology?
doesn't take genetics or lifestyle into account
Social ecological model
factors that influence a person's health/choices
Income vs. consumption vs. wealth
- income --> the amount that can be spent/consumed within a given time
- consumption --> amount of resources actually used within a given time
- wealth --> total value of assets and liabilities at any point in time
the study of overlapping or intersecting social identities and related systems of oppression, domination or discrimination
Observation about immigrants and their health over time?
first generation migrants are generally much healthier than their children (health gets worse over time) -- don't know why
2 examples of disparities in health care?
- blacks have a higher rate of infant mortality than other racial groups
- blacks go to the emergency room more than regular doctor's office
Gender vs sex
- gender --> socially constructed term referring to roles, behaviors, activities, and attributes that a given society considers appropriate for men & women
- sex --> defined biologically & physiologically
a person's emotional, sexual, and/or relational attraction to others
MSM vs. WSW acronyms
- msm = men who have sex with men
- wsw = women who have sex with women
person's internal sense of being male, female, or something else
denying any non-heterosexual behavior
fear/hatred of somebody because they are trans
the higher your social integration, the _________
higher your social construct
when is environmental justice achieved?
when everyone, regardless of race, culture, or income enjoys the same degree of protection from environmental and health hazards and equal access to the decision-making process to have a healthy environment in which to live, learn and work
what are neglected tropical diseases?
a medically diverse group of tropical infections which are especially common in low-income populations in developing regions of Africa, Asia and the Americas
3 types of disease prevention
- primary - reducing the risk and avoiding problems before they start
- secondary - taking action to stop risk behaviors before an actual illness
- tertiary - treatment / rehabilitation after an illness
Stages of change model is also known as?
Stages of Change Model (list 6 steps)
- pre contemplation --> no intention to adopt change within next 6 months, unaware of their issues
- contemplation --> acknowledges there is a problem, intends to make change within the next 6 months but not committed yet
- preparation --> planning on making behavior change within the next month, may doubt their abilities but collects info
- action --> now making changes to modify behaviors, this phase includes a lot of time, money and energy
- maintenance --> sustain changes for 6 months or more, try to prevent relapse and avoid temptations
- relapse --> going back to previous behavior, can happen at any stage throughout the cycle