Epidemiology and Biostats Flashcards
Epidemiology
the core science of public health
- the study of the distribution of disease amoung populations
- Investigate causes of diseases
- Identify trends in disease (reporting of “notifiable” diseases)
- Evaluate interventions
What is Epidemiology?
The study of the distribution and determinants of health and disease-related states in populations, and the application of this study to control health problems.
- distribution
- determinants
- populations
What do we mean by distribution?
Standard dimensions used to track the occurrence of a disease/health event
- person
- place
- time
Distribution
person
- age, sex, race, occupation marital status
place
- physical, biological, social environment
time
- calendar months
Determinants
host
- refers to who has the disease
agent
- anything that causes the disease (chemical, bacteria, nutrition related)
environment
- what in the environment allows this disease to happen and spread?
Populations
group of people who share a common characteristics
Patterns of disease occurrence (3Ws)
Who is getting the disease?
When did they get the disease?
Where is the disease occurring?
From this information, epidemiologists can infer why the disease is occurring.
- i.e. John Snow followed this procedure
Numerator
A measure of the frequency with which an event occurs; Number of people with the health outcome (“disease” broadly”)
Denominator
Number of people who are at RISK of getting the disease
Incidence (risk)
The number of NEW cases in a population
Prevalence
The number of TOTAL cases in a population during a specific time period; a proportion (of the population that has the disease)
Incidence (Risk) Formula
(# new cases / # of ppl at risk *excluding existing cases) x 100
What information does incidence convey?
conveys information about the RISK of contracting a disease over a certain time period
Prevalence Formula
(# of cases in the present population / total # of people in the population) * 100
What information does prevalence convey?
the proportion of a population who has the health outcome at a given period of time; conveys information about how WIDESPREAD a disease is during a certain time period
Incidence or prevalence?
32,100 new HIV infections per year
Incidence or prevalence?
Currently an estimated 1.2 million persons aged 13 years and older are living with HIV
If we think of the marble jar, why can prevalence grow?
Prevalence grows when diseases become chronic.
i.e. prevalence of HIV in the US; we are getting better at treating it so people can live with it (less dying and leaving the bucket)
Assuming that we begin to measure incidence of breast cancer among women on January 1, 2018, which group in Massachusetts would be counted for the denominator of the incidence measure?
A. All men and women in Massachusetts in 2018
B. All women in Massachusetts in 2018
C. Only women in Massachusetts without breast cancer on January 1, 2018
C. Only women in Massachusetts without breast cancer on January 1, 2018
*for incidence
(only looking for those at risk, so excluding the people who have the disease)
Who is the father of epidemiology and what did he do?
John Snow
- cholera epidemic in London 1850
Q: What was the risk among those who ate guacamole?
Step 1: Rate among guacamole-eaters: 32/80 = 40%
Step 2: Rate among non-guacamole eaters: 93/170 = 55%
Step 3: Rate ratio: (32/80)/(93/170)= 0.73
Endemic
The constant presence and/or usual prevalence of a disease or infectious agent in a population within a geographical area
Epidemic
Sudden increase in the number of cases of a disease above what is normally expected in that population in that area
Pandemic
An epidemic that has spread over several countries or continents, usually affecting a large number of people
Biostatistics
- The numbers that describe the health of the
population - The science used to interpret these numbers
-The uncertainty of science – science is ongoing and statistics can help quantify the degree of uncertainty - methodological tool
- Translate data into information about causes and effects, health risks, and interventions (policies, cures, etc.)
association
presence of a relationship btwn variables… cause?
confounding
the “third factor” or a separate factor that may explain an association between exposure and outcome
Risk Ratio
Risk Exposed / Risk Unexposed
*risk = incidence
Rate Ratio
rate exposed / rate unexposed
Rates (types)
- Crude rates
- Adjusted rates
- Group specific rates
Rates (definition)
relate the raw numbers to the SIZE of a population
Descriptive statistics
describe, show, or summarize data in a meaningful way (who, what, when, where)
Inferential statistics
Draw conclusions from samples of data;
i.e. infer what is happening in the population (why?)
Case definition
set of uniform criteria to define a disease for public health
T/F case definitions can change overtime was we get more data?
T (i.e covid)
Surveillance
the ongoing, systematic…
- collection
- analysis
- interpretation, AND
- dissemination
….of health outcome data
(– guides health action – which can be used to guide population healthy programs and policy)
Example of exposure / risk –> outcome/disease
Is there a relationship between taking PHCG & Pursuing a masters in PH?
- taking PHCG = exposure (risk factor)
- pursing a masters = outcome or disease
