35 Cards in this Set
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Ratio
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No implicit relationship
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Risk
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Accumulated Effect
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Incidence
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= # new cases/pop. at risk over time frame
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Prevalence
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= Total # Cases/Pop. at Risk
(@ one point in time)
P= (a+c)/N
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Relative Risk
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= IR exp/ IR unexp
Measures strength of association
= [a/(a+b)] / [c/(c+d)]
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Cumulative Incidence
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= # new case during a period of time/# of disease-free individuals at the beginning of the observation period
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Incidence Density
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= # new cases during a period of time/divided the total time contributed by each disease-free individual
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Point Prevalence
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# of cases in a population at that instant in time you count
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Period Prevalence
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# of cases in population over a period of time that it takes to collect information
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IR exp (table)
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= a / (a+b)
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IR unexp (table)
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= c / (c+d)
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Attack Rate
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= # ill/# at risk
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Crude Rate
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= (# deaths / pop.) = 1000
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Cause Fatality Rate
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= # deaths due to disease/# cases of disease
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Attributable Risk
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= IR exp - IR unexp
excess risk
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Epidemiology
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The study of the distribution of disease and the determinants of disease in human populations
Care about behavior of whole group, not the individual
Interested in homogeneity & variability
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Inductive Reasoning (Logic)
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Always involves uncertainty
Most use this b/c we go off of our instincts
Usually based on facts or observations
Not necessarily a logical relationship btw premises & conclusion
We then generate a hypothesis through descriptive studies
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Deductive Reasoning (Logic)
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(Ingenious) Major reasoning process
Conclusions drawn from general principles or premises (premises = proposition from another)
Conclusions from deductive interference one certain, provided the premises are true
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"Why Bogus Therapies Seem to Work" Article
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Why do people pay a lot for treatment not proven to work
Vigorous marketing of unsubstantiated claims by "alternative" healers
From popular "counter culture"
People say "I tried it, I got better, it must be effective"
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Illness/Disease (article)
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Disease-pathological state of the organism due to infection, etc
Illness-feeling of pain, dysfunction, or other complaints that might accompany a disease
Sickness - society says you're "sick"
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Errors & Biases (article)
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1. The disease may have run its natural course
2. Many diseases are cyclical
3. Spontaneous remission (rare but happens)
4. The placebo effect
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Purposes of Epidemiology
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1. Identify causes & risk factors
2. Determine extent of disease in the community
3. Study natural history & prognosis of disease
4. Evaluate preventative & therapeutic measures
5. Provide foundation for public policy
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Central Axiom
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Epidemiology:
Disease does not distribute randomly (in time & space) in human populations (groups, however defined)
About "difference"
Recognizes spatio-temporal patterns of disease occurrence
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Epidemic
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The occurrence in a community or region of cases of an illness, specific health-related behavior, or other health-related events clearly in excess of normal-expectancy
Babylonian BC: plague
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Descriptive Epidemiology
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Examining the distribution of a disease in a population & observing the basic features of its distribution in terms of time, place & person
ex) community health survey
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Analytic Epidemiology
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Testing a specific hypothesis about the relationship of a disease to a putative cause, by conducting an epidemiologic study that relates the exposure of interest to the disease of interest
ex: cohort, case-control (retrospective)
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The Person (part of the triad)
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Age
Socio-Economic Status (SES)
Ethnicity/Race
Gender
Behavior
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8 Criteria Guidelines for Establishing Causation
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Temporal Relation Plausability
Consistency
Strength
Dose-response relationship
Reversibility
Study design
Judging the Evidence
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Latent Class Variables
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Variables you can’t measure directly (behavioral health variables: anxiety, headache, etc.)
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Confounding
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Covariates in model that are very hard to disentangle
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RR or OR > 1
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The exposure is more associated with the “cases” versus “non-cases”, therefore it may be a cause.
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RR or OR is = 1
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The exposure occurs equally in “cases” and “non-cases”, therefore it probably isn’t causing “casness”
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RR or OR < 1
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The “caseness” is occurring more frequently in the unexposed. Therefore exposure could be protective, or some variable in the unexposed may be the cause of “caseness”
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Sensitivity
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Ability to correctly identify person with disease (+ result in diseased person)
= a / (a+c)
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Specificity
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Ability to correctly identify person without disease (neg result from non-diseased person)
= d / (b+d)
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Study Guide: Exam 1