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Public Health Research & Practice
Review for Final Exam
146
Other
Undergraduate 2
05/10/2010

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Cards

Term
Nested Case Control Study
Definition
Conduct a case control study within the context of a cohort study
Term
Cohort Study
Definition
Identify cause of disease by studying how exposed people differ from unexposed people (subjects chosen based on exposure status)
Term
Prospective Cohort Study
Definition
Follow cohort forward in time from exposure assessment at the start of the study and document who gets the outcome
Term
Retrospective Cohort Study
Definition
Use past exposure status to do the study (Follow-up for disease development is from the time of exposure (past) until the time of study (present))
Term
Historical Prospective
Definition
Exposure occurred in the past (Follow up for disease occurrence from past to present and then into future)
Term
Information Bias
Definition
Systematic problems with the way data are gathered and recorded (Hawthorne effect and surveillance bias)
Term
Relative Risk
Definition
Describes the risk of exposed for developing the disease compared to those who are unexposed

RR = [a(c+d)]/[c(a+b)]
Term
Nested Case Control Study
Definition
Conduct a case control study within the context of a cohort study
Term
Analytic Studies
Definition
Test hypotheses by describing associations between risk factors and outcome

Two categories: Observational and experimental
Term
Observational Study
Definition
Type of analytic study that observes the natural exposure-disease relationship

Includes case control, cohort, and nested case control
Term
Experimental Study
Definition
Type of analytic study that manipulates the factors that affect outcome
Term
Descriptive Studies
Definition
1. Describe health trends
2. Describe correlations between exposure and outcome
3. Formulate hypotheses

Include ecological and cross-sectional studies
Term
Ecological Study
Definition
Type of descriptive study that uses group data to show overall trends; cannot be used to asses individual risk (no comparison group!)
Term
Cross-sectional study
Definition
type of descriptive study that measures prevalence and shows general relationships between risk factors and disease (no temporality!)
Term
Ecological fallacy
Definition
Make assumption about individuals based on group data
Term
Hippocrates
Definition
Described disease from a rational rather than supernatural basis

Observation key to understanding

Studies malaria and yellow fever

Coined terms "epidemic" and "endemic"

Related disease to environment, time, seasons
Term
John Graunt
Definition
Described birth and death trends in London

Used mortality tables and stats

Surveillance and stats can help determine research priorities
Term
Edward Jenner
Definition
Cowpox/Smallpox innoculation

One of the earliest clinical trials

Ethical considerations

Development of vaccination programs
Term
Ignaz Semmelweis
Definition
Death rate from "childbed fever" higher in wards staffed by med students than midwives

Behavioral interventions and hygiene measures (hand washing)
Term
John Snow
Definition
London cholera epidemic

Descriptive and analytic research

Outbreak investigations

"Shoe-leather" epidemiology
Term
Alexander Langmuir
Definition
Founder of the US surveillance system

EIS
Term
Belmont Report - basic ethical considerations
Definition
1. Respect for persons (informed consent)

2. Beneficence (risk-benefit assessment)

3. Justice (equal opportunity in selection of subjects)
Term
Proportion
Definition
A/(A+B)
Term
Rate
Definition
Rate = Frequency over time/size of population
Term
Incidence
Definition
Describes how quickly disease develops over a period of time

Incidence = # new cases over time/population at risk
Term
Prevalence
Definition
Proportion

Prevalence = # existing cases (old and new) / total population
Term
Prevalence =
Definition
Incidence x Duration
Term
3 Categories of Rates
Definition
1. Crude rates
2. Specific
3. Adjusted
Term
Crude Birth Rate
Definition
# births within a specific period of time / total population
Term
Specific Rates
Definition
Examine rates within the context of structural differences in a population
Term
Adjusted Rates
Definition
Allow for comparisons of rates for entire populations, taking into account structural differences
Term
Cause-Specific Death Rate
Definition
Rate of death from a particular disease

= (# deaths from a particular disease / population at risk) * 1000
Term
Case Fatality Rate
Definition
Rate of death from a particular disease among those who have the disease

= (# deaths from a specific disease / population with the disease) * 1000
Term
Behavioral Risk Factor Surveillance System (BRFSS)
Definition
Est. in 1984 by the CDC

Largest ongoing telephone health survey in the world

Monthly data collection from about 350,000 people each year

Identify emerging health problems, establish objectives, develop programs, etc.
Term
WHO: Surveillance of Risk Factors
Definition
Country-level data that focuses on non-communicable diseases
Term
Secular trends
Definition
Trends over long periods of time
Term
Seasonal Variation
Definition
Trends change with the season
Term
Null Hypothesis
Definition
There is no difference between the groups
Term
Alternative Hypothesis
Definition
The groups differ from one another
Term
Type I Error
Definition
Reject null hypothesis when it is true

Find a difference when there isn't one
Term
Type II Error
Definition
Fail to reject null hypothesis when it is false

Find no difference when one really exists
Term
Power of a Study
Definition
Ability to detect with sufficient precision that an association exists (how much Type II error we're willing to take)

Prob. that the study will find an association of a particular size if it truly exists in the general population

80% is a solid study
Term
Statistical Significance
Definition
Results are unlikely to have happened by chance

Measured by p-value and by 95% Confidence Interval (CI)
Term
p-value
Definition
Describes likelihood that results occurred by chance

p<0.05
Term
95% Confidence Interval (CI)
Definition
Describes the range of results expected 95% of the time the study is done

Null value for RR and OR is 1.0
Term
Clinical Significance
Definition
The ability of a factor to impact health

A result might not be statistically significant but might still have clinical significance
Term
Conceptualization of variables
Definition
Process of specifying/defining concepts to be studied (defining key terms for your research)

Concept = mental image or idea; summary of observations, ideas, or feelings (ex – quality of life, SES)
Term
Operationalization of variables
Definition
Process of specifying the variables that will measure a concept
Term
Index
Definition
composite measure that involves combining responses to several questions that are intended to measure the same idea
Term
Scale
Definition
Similar to index, but different weights are given to each question
Term
Single indicator
Definition
one indicator used to measure a variable
Term
composite indicator
Definition
multiple indicators needed to measure a variable
Term
Triangulation
Definition
Using two or more different methods to gather information about a same variable (such as, directly asking a question, observation, using existing information)

Lends confidence that we are measuring the “right” concept
Term
nominal measurement
Definition
No implied order to response options

Number is simply a “label” without numerical meaning

Ex: race, blood type
Term
ordinal measurement
Definition
Attributes can be rank-ordered

Distances between attributes does not have meaning

Ex: level of education
Term
interval measurement
Definition
Distance between attributes has meaning

“Equal distances” between points

There is no absolute zero that is meaningful

Ex: blood sugar level, temperature
Term
ratio measurement
Definition
Absolute zero is meaningful
Term
Likert Scales
Definition
Range of options balanced between positive and negative

Typically a 5-point scale
Term
Reliability
Definition
Ability to reproduce the data

Consistency or stability of the measure
Term
Validity
Definition
ability to measure the "true" value

extent to which the question, index, or scale measures what it is supposed to measure
Term
External validity
Definition
how well the results can be applied to the target population
Term
Henle-Koch Postulates
Definition
1. The agent is present in every case of the disease.

2. The agent does not occur in any other disease by chance or as a non-pathogenic parasite.

3. The agent can be isolated and causes disease if healthy people are exposed to it.
Term
Epidemiologic Triad
Definition
Disease is the result of the interaction of three factors: agent, host, and environment

(Works a little better than HK postulates with NCD)
Term
Hill's Postulates
Definition
Criteria to infer a causal relationship

1. Strength of Association
2. Consistency of Observed Data
3. Specificity
4. Temporality
5. Biologic Gradient ("Dose Response")
6. Biologic Plausibility
7. Coherence
8. Experiment
9. Analogy
Term
Case Control Study
Definition
Identify cause of disease by studying how diseased people differ from non-diseased people

Select subjects based on disease (outcome) status

Retrospective study --> no temporality!
Term
Odds Ratio (OR)
Definition
measure of association for case control studies

Likelihood that diseased people had the exposure relative to those without

OR = (a*d)/(b*c)

(people that make sense/people that don't make sense)
Term
Selection Bias
Definition
Systematic error in choosing the study population

Types:
1. Response bias
2. Exclusion bias
3. Berksonian bias
Term
Information Bias
Definition
Systematic error in the measurement of outcome and/or exposure

Types:
1. Recall bias
2. Interviewer bias
Term
Intervention Studies
Definition
experimental design

use multicenter randomized controlled trials (RCTs)
Term
Phases of Clinical Trials - Phase I
Definition
Establish effects of new drug and optimal dose range (high risk phase)
Term
Phase II
Definition
Determine therapeutic efficacy (what dose will have an effect?) in diseased group
Term
Phase III
Definition
Test against other therapies or placebo (very large, many people)
Term
Phase IV
Definition
Test for other uses of the therapy (after the drug is on the market)
Term
"Traditional" RCT
Definition
Minimum of two groups:

1. intervention group - exposed to new intervention

2. control group - not exposed to new intervention (placebo or SOC)
Term
Crossover design
Definition
subjects serve as own controls
Term
factorial design
Definition
use each participant to test two (or more) interventions that act independently of one another
Term
Mosely's Randomization
Definition
stratified groups depending on severity of disease to avoid the confounding variable of how sick people were to begin with
Term
potential problems in intervention studies
Definition
volunteerism, surveillance bias, hawthorne bias, loss-to-follow-up
Term
volunteerism
Definition
After screening, the experimental group may no longer be generalizable to the reference population
Term
surveillance bias
Definition
Ensure that you do not monitor the experimental group more carefully than the control group in intervention studies
Term
Hawthorne bias
Definition
people behave differently when they're being watched
Term
loss-to-follow-up
Definition
People who drop out from the study may be different from those who stay in the study
Term
controlling for bias and confounding in intervention studies
Definition
1. Restriction
2. Randomization
3. Masking (Blinding)
Term
Qualitative Research
Definition
collection and analysis of data that is in the form of words, pictures, sounds, or visual images
Term
what qualitative research is used for in PH
Definition
problem identification, program planning, implementing research, assessment and evaluation
Term
cognitive testing
Definition
Develop and refine survey measures

Small group of participants
Term
All-things-considered Technique
Definition
"If you had one minute to tell your professor what you think about attendance, what might you say?"
Term
Deductive Coding vs. Inductive Coding for qualitative research
Definition
Deductive - pre-set

Inductive - from the data
Term
Individual Interviews
Definition
Generate in-depth responses

Gather life histories or narratives

Not influenced by opinions of others
Term
Focus Groups
Definition
Observe interaction between participants

Efficient way to generate a range of responses

Decrease power differential between researcher and participant
Term
OMB Racial Categories
Definition
White (Origins in any of the original peoples of Europe, Middle East, or North Africa)

Black/African American (Origins in any black racial group of Africa)

Asian (Origins in any original peoples of the Far East, Southeast Asia, or Indian subcontinent)

American Indian and Native Alaskan (Origins in North, South, and Central America; includes people who maintain tribal affiliation)

Native Hawaiian/Other Pacific Islander (Origins in the poeples of Hawaii, Guam, Samoa, or other Pacific Islands)
Term
Primary Data
Definition
collected by the investigator him/herself
Term
secondary data
Definition
data collected by another investigator for another purpose
Term
Criteria for Selecting Data (Know this!!)
Definition
1. Nature of data (why, where, how, when)

2. Availability (how accessible)

3. Completeness (generalizable to the population of interest?)

4. Strengths and Limitations (problems? valid? reliable?)
Term
National Center for Health Statistics
Definition
Maintains a federal register of vital statistics data

Sets min. guidelines, but states may collect additional info
Term
Rochester Epidemiology Project
Definition
Geographically isolated healthcare system

Provides primary, secondary, and tertiary care in all medical specialties

Linkage system gives access to medical information on residents of Rochester, MN, and Olmsted County, MN
Term
NHANES
Definition
(National Health and Nutrition Examination Survey)

National health study

Three sources of information: health survey, lab tests, physical exams

Provides baseline health info not otherwise available for US population

HHANES - hispanic version
Term
HINTS
Definition
(Health Information National Trends Survey)

Biennial, cross-sectional survey

Purpose: study health communication, especially internet usage for health information

Good source for questions
Term
YRBSS
Definition
(Youth Risk Behavior Surveillance Study)

Biennial CDC school-based survey

Monitors health-risk behaviors and prevalence of obesity and asthma
Term
MEPS
Definition
(Medical Expenditure Panel Survey)

Survey families, individuals, and their medical providers and employers

Purpose is to learn about type, frequency, and cost of health services and health insurance

Relationship between disease and employment, evaluate Medicare Part D
Term
primary disease prevention
Definition
reduce incidence of disease
Term
secondary disease prevention
Definition
early detection, reduce mortality
Term
tertiary disease prevention
Definition
reduce recurrence and complications, rehabilitation, improve quality of life
Term
High Risk Prevention Strategies
Definition
Difference populations have specific concerns and needs

Target vulnerable populations

Ex - needle exchange
Term
Mass Prevention Strategies
Definition
Premise - disease and exposure reflect societal behaviors and circumstances

Targets large-scale population
Term
Yield
Definition
amount of previously unrecognized disease that is identified via screening
Term
validity (of screening)
Definition
ability to predict who does and doesn't have the disease
Term
Sensitivity
Definition
The ability to correctly identify those with disease

The probability of having a positive test if one has the disease (few false negatives)

Sensitivity = a / (a+c)

= true pos / (true pos + false neg)
Term
Specificity
Definition
The ability to correctly identify those without disease

The probability of having a negative test if you don't have disease (few false pos.)

Specificity = d / (b+d)

= true neg. / (true neg. + false pos.)
Term
optimize sensitivity when you can...
Definition
prevent transmission
Term
optimize specificity when...
Definition
there is no treatment
Term
Lead time bias
Definition
bias in screening - perception that screening increases survival, but it only increases time from diagnosis to recovery/death
Term
Selection bias (Volunteerism)
Definition
probability of disease is affected by motivation to be screened
Term
Positive Predictive Value
Definition
Probability of having disease if you test positive

= a/(a+b)

= true pos / (true pos + false pos)
Term
Negative Predictive Value
Definition
Probability of not having disease given a negative test

= d/(c+d)

= true neg / (true neg + false neg)
Term
Efficiency
Definition
Accuracy of the test

= (a+d)/(a+b+c+d)
Term
direct disease transmission
Definition
no intermediate source

"person to person"

ex - TB, flu, measles, chlamydia, syphilis
Term
indirect disease transmission
Definition
intermediary source involved

common vehicle (ex - potato salad)
vector (ex - rat)
fromite (inanimate objects, like a door handle)
Term
gastrointestinal tract
Definition
salmonella
Term
respiratory tract
Definition
diphtheria
Term
genitourinary tract
Definition
gonorrhea
Term
percutaneous
Definition
tetanus, lyme disease
Term
incubation period
Definition
time between exposure and first sign of disease
Term
Infectivity
Definition
Ability to invade a host (Of all expose, who gets infected?)

(# infected/# susceptible) * 100
Term
Pathogenicity
Definition
Ability to cause clinical disease (Of all infected, who gets the disease?)

(# clinical disease/# infected) * 100
Term
Virulence
Definition
Severity of disease (Of all diseased, how many die?)

(# deaths/# of people with disease) * 100
Term
Endemic
Definition
background cases, expected number of cases
Term
Epidemic
Definition
excess number of cases in a localized area
Term
Pandemic
Definition
excess number of cases worldwide
Term
Steps to Investigating an Outbreak (Know these!)
Definition
1. Verify the outbreak
2. Plot an epidemic curve
3. Calculate attack rates
4. Determine the source of the outbreak
5. Recommend and implement control measures
Term
Point source transmission
Definition
most common type of food-borne outbreak, short exposure period
Term
Continuing source transmission
Definition
several peaks of cases

difficult to characterize incubation period
Term
vector borne transmission
Definition
Disease accumulates and tapers off slowly

Incubation period estimated by time between first case and peak of cases

ex - seasonal diseases
Term
Attack Rate
Definition
= (# ill/(ill+well)) * 100
Term
Norwalk Article
Definition
Boxed lunch foodborne illness
Term
HAI
Definition
Healthcare Associated Infections

Nosocomial infection among the 10 leading causes of death in the US
Term
National Children's Study
Definition
National scope - household sampling

Broad approach to environment

long-term longitudinal
Term
subthreshold
Definition
at low exposure levels, increase in dosage yields no effect
Term
threshold
Definition
lowest dose at which a response occurs
Term
latency
Definition
time between initial exposure and measurable response
Term
synergism
Definition
combined effect of several exposures is greater than the individual effects
Term
Minamata Bay Disaster
Definition
1932-1968 - 27 tons of mercury compounds dumped into Minamata Bay Chisso Corp.

Mid-1950's - "strange happenings" in Minamata
Term
Arsenic
Definition
Natural component of soil, groundwater, and air

Higher concentrations in urban areas

Non-occupational exposure primarily through water and food

Linked to skin and lung cancer, hypertension, and neurotoxticity
Term
Radon
Definition
Odorless, tasteless, colorless gas produced when uranium decays in soil and water

Form of ionizing radiation

#1 cause of lung cancer in non-smokers
Term
Sick Building Syndrome
Definition
Acute health effects linked to time spent in a building, with no know etiology
Term
Love Canal
Definition
Toxic waste site near Niagra Falls, NY

Contaminants leached into homes and local water supply

Increased number of congenital birth defects
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