Research Exam 2

Front 1

Research in the PA Profession

Back 1

improving patient care

clinical guidelines

healthcare policies

expanding the scope of PA practice

Front 2

Changing Trend of PA Program

Back 2

educating PA students about research methodologies

data collection

critically appraised research findings

More PA faculty are involved in clinical, educational, and workforce research

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Kochs Postulates

Back 3

specific organism must always be observed in assoc with disease

organism must be isolated from an infected host and grown in pure culture in the lab

when organisms from pure culture are inoculated into a susceptible host organism, it must cause the disease

the infectious organism must be re-isolated from the diseased organism and grown in pure culture

Front 4

The Research Process

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1. research idea
2. literature review
3. theoretical formulation of the research problem
4.empirical research question (operationalization)
5. research design (planning)
6.data collection
7. data analysis
8. answering empirical research questions
9. theoretical interpretation of the results
10. comparison with earlier research
11. conclusions

Front 5

Study Protocol

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anatomy and physiology of research

Front 6

anatomy of research

Back 6

research question
significance
design
subjects
variables
statistical issues

Front 7

origins of research questions

Back 7

build on experience

review existing literature in an area of study

attend national meetings and journal clubs

observation of patients

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characteristics of good research question

Back 8

feasible
interesting
novel and original
ethical
relevant

Front 9

feasibility

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adequate number of subjects

adequate technical expertise

affordable (time and money)

Front 10

novelty

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confirms or refutes previous findings

extends previous findings

provides new findings

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relevancy

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to scientific knowledge

to clinical and health policy

to future research directions

Front 12

design types

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observational
-cross section
-cohort
-case control

experimental
-randomized trials
-basic science research

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epidemiologic prototypes

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-cohort study
-cross sectional study
-case control study
-randomized trial

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major decisions for subjects

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specifying selection criteria

sampling

Front 15

statistical issues

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sampling size estimation

managing and analyzing data

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physiology of research

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findings in the study -->infer--> truth in the universe

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goal

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to draw inferences from the study results about the nature of truth in the universe

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random error

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wrong result due to chance

remedy by increasing sample size

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systematic error

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wrong result due to bias, or error that occurs consistently with an instrument

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internal validity

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degree to which the investigator's conclusions correctly describe what actually happened in the study

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external validity

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degree to which the conclusions are appropriate when applied to the universe outside the study

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predictor variable (independent)

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presumed cause of the dependent variable

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outcome variable (dependent)

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presumed effect of an independent variable

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confounding variables (intervening of extraneous variables)

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phenomena that has an effect on study variables but are not necessarily the objects of the study

Front 25

cohort studies

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involves following groups of subjects over time

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cohort study types

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prospective studies

retrospective studies

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strengths of prospective cohort studies

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true estimates of absolute risks may be obtained

many different disease outcomes may be studied

data collection may be controlled by the investigator, so that outcome events may be confirmed

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weaknesses of prospective cohort studies

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very expensive and inefficient

long wait for results

only risk factors that have been defined and measured in the beginning of the study can be assessed

sometimes affected by confounding variables

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steps of prospective cohort design

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select sample

measure predictor variables (risk factor present of absent)

follow up cohort

measure outcome variables (disease present of absent)

Front 30

steps of retrospective cohort design

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identify cohort that has been assembled in the past

collect data on predictor variables (measured in the past)

follow up the cohort

collect data on outcome variables (measured in the past or present)

Front 31

what do cohort studies describe

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incidence and relative risk

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incidence

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proportion of population who get the disease over a period of time

Front 33

relative risk

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ratio of the risk of an outcome in persons with the factor of interest to the risk in those without the factor

(ratio of outcome in exposed subjects/unexposed)

Front 34

when to use cohort design

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incidence and natural Hx of a condition

often the only way to establish the temporal sequence of predictor and outcome variables

cohort studies are the only way to study certain rapidly fatal diseases

permit the investigator to study numerous outcome variables, whereas case controlled is limited to a single outcome

as follow up of a cohort study continues and more events accumulate, a cohort study gains power to study an ever increasing number of health outcomes

Front 35

cross sectional studies

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similar to cohort except all measurements are made at once, no follow up period

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what do cross sectional studies study

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prevalance of condition/disease

Front 37

steps for cross sectional design

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select sample

measure predictor and outcome variables

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strengths of cross sectional study

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fairly quick, easy and inexpensive

determine prevalence of risk factors and frequency of prevalent cases of disease for a defined population

assessing current health status of a population

use in infectious disease epidemiology for establishing antibody levels indicative of past exposures and the degree of population immunity

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weaknesses of cross sectional study

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temporal relationships remain uncertain because data on exposures and outcomes are obtained simultaneously (difficulty of establishing causal relationships)

impractical for the study of rare diseases

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prevalence

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proportion of population who have a disease at one point in time

Front 41

statistics for expressing disease frequency in observational studies

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prevalence (cross sectional) - number of people who have the disease/number of people at risk

incidence (cohort) - number of new cases of a disease during a period of time/ number of people at risk during a period of time

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case control studies

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investigator identifies groups of subjects with and without the disease, then looks backward in time to find differences in the predictor variables that may explain why the case got the disease and control did not

Front 43

case control studies begin with...

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begin with sample of Cases and Controls

Start with Disease status, then assess and compare Exposures in cases vs Controls

Front 44

cross sectional studies begin with...

Back 44

begin with cross sectional sample

determine Exposure and Disease at same time

Front 45

cohort studies begin with...

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begin with Healthy Cohort

Start with Exposure status, then compare subsequent disease experience in exposed vs unexposed

Front 46

case control design steps

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select sample with the disease (cases)

select sample at risk (controls)

measure predictor variables

Front 47

strengths of case control studies

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quick and inexpensive

useful when the outcome is rare

many risk factors (exposures may be considered)

Front 48

weaknesses of case control studies

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risk of recall bias

difficulty in determining proper control groups

actual risk of outcome cannot be determined but is estimated by odds ratio

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what is an odds ratio

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calculated by dividing the odds in the treated or exposed group by the odds in the control group.

an odds ratio greater than 1 implies a positive association between the exposure and the condition of interest

odds = probability / 1 - probability

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interpreting the odds

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odds greater than 1 = event is more likely to happen than not

if odds are less than 1, chances are that the event wont happen

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ideal diagnostic tests

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positive result in everyone with the disease and neg result in everyone else

quick, safe, simple, painless, reliable and inexpensive

(strep test, preg test, urinalysis etc)

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structure of diagnostic tests

Back 52

straightforward structure, similar to other observational studies
they have
1. predictor variable (test results)
2. outcome variable (presence of absence of the disease)

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sensitivity

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ability of a test to detect a disease when it is present

TP / TP + FN

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specificity

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ability of a test to indicate nondisease when no disease is present

TN / TN + FP

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randomized controlled clinical trials (RCCT)

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used to test therapeutic interventions in ill persons

Front 56

randomized controlled field trials (RCFT)

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used to test preventative interventions in well persons

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disadvantages of experimental designs

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often costly in time and money

may be ethical barriers

outcomes may be too rare

standardized interventions may be different from common practice (reducing generalizability)

restrict the scope and narrow the study question

Front 58

advantages of experimental designs

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can produce strongest evidence for cause and effect

can be the only possible design for some research questions

sometimes can be faster and cheaper than observational