Transcript Unit 11: Evaluating Epidemiologic Literature Unit 11 Learning Objectives: 1. Recognize uniform guidelines used in preparing manuscripts for publication in peer reviewed epidemiologic journals. 2.

Unit 11:
Evaluating Epidemiologic
Literature
Unit 11 Learning Objectives:
1. Recognize uniform guidelines used in
preparing manuscripts for publication in peer
reviewed epidemiologic journals.
2. Understand general guidelines used to
evaluate epidemiologic literature.
Overview
---Publication in “respected” epidemiologic
journals involves “peer review”, a process
in which outside “experts” review the
suitability
of manuscripts submitted for
publication.
---In spite this system of checks and balances,
numerous examples abound of published
epidemiologic studies with poor designs,
inappropriate analyses, and
unsubstantiated
conclusions.
Overview
---In virtually all epidemiologic journals, as well
as journals from other disciplines, a
standard
format is used for manuscript
preparation:
---
Abstract (summary of the paper)
---
Introduction
---
Methods
---
Results
---
Discussion
Overview
Within the health sciences, uniform
guidelines for manuscript preparation
are provided in the document:
“Uniform Requirements for Manuscripts
Submitted to Biomedical Journals”
Manuscript Format
Abstract (summary of the paper):
---Usually 250 words or less.
---Contains a brief summary of each major
section of the paper (introduction, methods,
results, conclusions).
---Probably the most important part of the
paper, since many persons will only read the
abstract.
Manuscript Format
Introduction:
---Typically limited to a few paragraphs.
---Frames the purpose and public health
significance of the research by contrasting
the study objective with a brief literature
review of current state of knowledge.
---The research hypothesis(es) to be
investigated/tested should be clearly
stated.
Manuscript Format
Methods:
---Describes how the study was carried out.
---Includes a description of the study
population, exposure and outcome variables,
data collection methods, statistical analyses,
etc.
---Should be of sufficient detail so that the
reader can critically evaluate the work without
having to consult outside sources.
Manuscript Format
Results:
---Describes what was found in the study.
---Should correspond directly with the stated
research hypothesis(es).
---Tables and figures should be judiciously
used; text descriptions should not be largely
redundant with data in tables and figures.
Manuscript Format
Discussion:
---Describes what was learned from the study
and public health implications of the findings.
---Should not be a large re-statement of text
from the Results section.
---Should not include presentation of “new”
findings not presented in Results section.
Manuscript Format
Discussion (cont.):
---Should contrast results with similar
previous studies, including possible
explanations for differences.
---Should candidly acknowledge study
limitations (all studies have some
limitations).
---Should state to whom the results most likely
apply (generalize).
General guidelines for
evaluating epidemiologic
literature
Evaluation Guidelines
In the subsequent slides, the
following abbreviations are used:
A:
I:
M:
R:
D:
Abstract
Introduction
Methods
Results
Discussion
Evaluation Guidelines
1. Presentation and Purpose of
Research Hypothesis
Is the research hypothesis(es) clearly
stated?
Does the study address an important
public health issue?
Is the purpose of the research supported
by a relevant review of the literature?
Section(s)
A, I
A, I
I
Evaluation Guidelines
2. Selection of Research Design
Does the study use an experimental or
observational design?
Is the study design appropriate for the
research hypothesis(es)?
Is the method in which the study design
was carried out clearly articulated?
Does the design represent an advance
over prior approaches?
Section(s)
A, M
M
M
M
Evaluation Guidelines
3. Study Population
Is it clear how study participants were
identified and selected?
Were the inclusion and exclusion criteria
clearly defined and appropriate?
Were the methods used in selecting study
participants appropriate (e.g. cases,
controls)?
Section(s)
A, M
M
M
Evaluation Guidelines
4. Exposure Ascertainment/Assignment
Section(s)
Is it clear how exposure variables/
exposed and unexposed persons were
identified?
Is the assessment of exposure likely to be
precise and accurate?
Was the method of exposure
quantification/classification appropriate?
Was exposure ascertainment uniformly
applied for all study participants?
A, M
M
M
M
Evaluation Guidelines
5. Outcome Ascertainment/Assignment
Section(s)
Is it clear how the study outcome(s) was
defined and classified?
Is outcome assignment likely to be precise
and accurate?
Was the method of outcome classification
appropriate?
Was outcome ascertainment uniformly
applied for all study participants?
A, M
M
M
M
Evaluation Guidelines
6. Statistical Methods
Are the statistical methods used clearly
described and appropriate?
Is the sample size adequate to answer the
research question (e.g. assessed through
description of power calculations)?
Have the assumptions underlying the
statistical tests in use been met?
Were appropriate methods used to control
for possible confounding?
Section(s)
A, M
M
M
M
Evaluation Guidelines
7. Presentation of Results
Do the results presented correspond
directly to the research hypothesis(es)?
Are the results presented by appropriate
use of text, tables, and figures?
Is it clear which potential confounding
variables were controlled for in the
analysis?
Section(s)
A, R
R
R
Evaluation Guidelines
8. Interpretation of Results/Conclusions
Section(s)
Overall, are the author’s conclusions
justified by the data presented?
Do the authors appropriately interpret the
clinical, biologic, and statistical
significance of the results?
Are the study findings compared and
contrasted with similar prior research?
Were measurement errors with regard to
exposure/disease classification discussed?
A, D
D
D
D
Evaluation Guidelines
9. Interpretation of Results/Conclusions
Section(s)
Has chance been discussed as a potential
explanation of the study results?
For non-significant results, do the authors
discuss if they had sufficient power?
Is the impact of the major possible sources
of bias (e.g. selection bias) discussed?
Do the authors consider/discuss whether
confounders could account for the
observed study results?
D
D
D
D
Evaluation Guidelines
10. Interpretation of Results/Conclusions
Section(s)
Do the authors appropriately acknowledge
limitations of their study?
Are the generalizability of the study
findings discussed and appropriate?
Do the authors provide suggestions for
future areas of investigation?
A, D
D
D
Class Exercise
From the article “Snoring as a Risk Factor for Type
Diabetes Mellitus: A Prospective Study (AJE 2002;
155:387-393):
Questions from the Abstract:
1) What was the primary exposure variable of interest?
2) What was the primary outcome variable of interest?
3) What type of epidemiologic study design was used?
4) What were the primary study inclusion criteria?
5) How was the primary exposure ascertained?
6) What were the general results overall for the association
between the exposure and outcome of interest?
7) Was there any suggestion of effect modification?
Class Exercise
From the article “Snoring as a Risk Factor for Type
Diabetes Mellitus: A Prospective Study (AJE 2002;
155:387-393):
Questions from Table 2:
8) What was the reference (control) group used in the
analysis?
9) The initial results were adjusted for age. Was the
evidence that body mass index (BMI) was a
confounder?
10) Provide an interpretation for the final results
presented in the multivariate adjusted model.