Evidence-Based Medicine 1 Knowledge and Skills for Critical Reading Karen Schetzina, MD, MPH.
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Transcript Evidence-Based Medicine 1 Knowledge and Skills for Critical Reading Karen Schetzina, MD, MPH.
Evidence-Based Medicine 1
Knowledge and Skills for Critical
Reading
Karen Schetzina, MD, MPH
Overall Objective
Become familiar with research methods
and explore issues that may lead to future
research interests, community service
activities, advocacy projects, or focuses of
study in your career.
Epidemiology
The study of the distribution and
determinants of health-related
states or events in specified
populations, and the application
of this study to the control of
health problems
Assumptions
Disease does not occur at random but is
related to environmental and /or personal
characteristics
Causal and preventive factors for disease
can be identified; knowledge of these
factors can then be used to improve
health of populations
Purposes of Epidemiologic
Studies
Identify new diseases
Identify populations at risk for a disease
Identify possible causative agents of a
disease
Identify factors or behaviors that increase
risk of disease and their relative
importance
Purposes of Epidemiologic
Studies (continued)
Rule out factors or behaviors as
contributing to a disease
Evaluate therapies for a disease
Guide in the development of effective
public health measures and preventive
strategies
Reading Epidemiologic Studies
Become familiar with medical terminology
(but you don’t need to know every word)
Have some prior knowledge of the
pathophysiology of the disease of interest
Understand principles of study design,
analysis, and interpretation
Pneumocystis Pneumonia
--- Los Angeles
Background Info/Definition of Terms
Opportunistic infections – occur only in persons with
abnormal immune systems
Pneumocystis carinii pneumonia
Cytomegalovirus (CMV) infection
Candidiasis/candida mucosal infection – yeast infection
Leukopenia / neutropenia – low white blood cell count
Viruria – virus detected in urine
Titre – antibody count
Neoplasia - cancer
Hodgkins Disease – a type of lymphoma (cancer)
Clinical Correlations
“Pneumocystis Pneumonia– Los
Angeles”
“First Report of AIDS”
Pneumocystis carinii pneumonia
(PCP)
• Caused by a microorganism
• Frequently seen in persons with
compromised immune systems:
AIDS patients
Elderly
Premature babies
• Presentation
Fever
Shortness of breath
Nonproductive cough
(Bilateral infiltrates- chest x-ray)
Cytomegalovirus (CMV)
Group of herpesviruses
Often infections are asymptomatic
If symptoms present:
Mononucleosis-like illness
Candidiasis (thrush)
Pneumocystis Pneumonia
--- Los Angeles
What type of article is this?
What do you think is/are the purpose(s) of the article?
From what population are the subjects of this report
derived?
What similarities between the cases were mentioned in
the article?
What conclusions did the editor reach?
What are the limitations of this type of report in terms of
the information it provides?
What are the public health implications of this report?
What questions arise after reading this report? What
future research is needed?
Anatomy of a Journal Article
Abstract
Introduction / statement of the problem
Methods
Results
Discussion
References
Definitions
Hypothesis or research question
Population – Collection of units from which a
sample may be drawn
Sample – A selected subset of a population
Variable - “Any quantity that varies. Any
attribute, phenomenon, or event that can have
different values.”
Predictor Variable – Risk factor
Outcome Variable – Disease or condition of
interest
Association or Correlation – Degree to which
variables change together
Definitions
Estimate – Incorporates some degree of error
Prevalence - “The number of events in a given
population at a designated time”
Incidence – “The number of new events in a
defined population within a specified period of
time”
Mean – average
Variance – A measure of dispersion or variation
Standard Deviation/Error – Square root of the
variance
Study Designs
Observational, Descriptive
Observational, Analytic
Experimental
Study Designs
Observational, Descriptive
Describe the amount and distribution of
disease
Useful for generating hypotheses
Observational, Analytic
Designed to test one or more specific
hypotheses
Experimental
The exposure and the persons to be exposed
are determined by the investigator
Study Designs
Observational, descriptive
Case reports, case series
Ecological
Cross-sectional
Observational, analytical
Case control
Cohort
Experimental
Randomized clinical trial
Community Intervention Trial