Transcript Writing and Reviewing Abstracts

Writing and Reviewing
Abstracts
Society for Epidemiologic Research –
Student Caucus
What is an abstract?

Concise summary of a full scientific research
project describing the study and its results

Abstracts generally include the most
important aspects of the study’s purpose,
design, findings, and implications
What do I include in an abstract?

Background and significance



Why do we care about the problem and results?
Include the importance of your work, challenges in
this research area, and the potential impact of
your work
Hypothesis


What question are you trying to answer?
What is the scope of your work?
What do I include in an abstract?

Methods




How did you address your hypothesis?
How did you collect your data?
What analytic methods did you use?
Results

What are some characteristics of your data?




Sample size
Age range
Racial breakdown
What did you find?

Report noteworthy results and findings
What do I include in an abstract?

Conclusions



What are the implications of your study?
Are the results generalizable?
What is the take home message for the audience?
Abstract considerations

Stay within the word limit





Most journals and conference submissions will not
accept abstracts that are over the word limit
Use active voice and simple sentences
Spell out any abbreviations
Think of key words for searches and be sure
to use them in your abstract
Have someone else review your abstract
before submission
Example Abstracts
Disclaimer: Abstract reviews are the opinions of the
SER-SC Executive Board
Sample 1: Home Use of Paints and Petroleum Products and Risk
of Childhood Leukemia
Associations between childhood leukemia and parental occupational exposures to
paints, solvents, and other petroleum products have been reported, however, little is
known about the effect of these products when used at home. The role of home
exposures to paints and petroleum products on the risk of childhood leukemia was
evaluated in the Northern California Childhood Leukemia Study (NCCLS), an
ongoing population-based case-control study. The current analyses include 382
incident leukemia cases (aged 0-14) enrolled from 1995-2002, and matched to 482
controls on age, sex, Hispanic status, and maternal race. A detailed history on
home use of paints and petroleum products, time of exposure, and user was
collected during an in home interview. Exposures were censored one year before
diagnosis. Conditional logistic regression was performed adjusting for annual
household income. An increased risk of childhood leukemia was observed with
parental use of paints anytime pre- or postnatally (Odds Ratio (OR)=1.35, 95%
Confidence Interval (CI)=0.99, 2.02), with a higher and significant risk when paints
were used during both time periods (OR=1.72, 95% CI=1.07, 2.74). Maternal use of
paints anytime pre- or postnatally conferred a significantly increased leukemia risk
(OR=1.44, 95% CI=1.03, 2.02), while non-significant increased risks were detected
for paternal use of paint anytime before or after birth. Exposures to paints by both
parents after birth resulted in a two-fold significant increased risk (OR=1.97,
95%CI=1.18, 3.30). Subjects with acute lymphoblastic leukemia had greater risks
compared to subjects with acute myeloblastic leukemia. No significant associations
were seen with exposure to petroleum products across all time windows for either
parent.
Why is sample 1 a good abstract?







Used active voice
Indicated the importance of their study
Described the larger study, years of use, and sample
size
Included information on study design and matching
variables
Provided statistical methods and used appropriate
methods to analyze matched data
Described results and appropriate conclusions
What could have improved this abstract?

Including summary conclusions
Sample 2: Association between body composition and blood
pressure in a contemporary cohort of 9-year old children
Background: Elevated blood pressure in children is an early risk factor for
cardiovascular disease and is associated with body mass index (BMI).
However as BMI does not distinguish between fat and lean, little is known
about the relationship of blood pressure in children to different elements of
body composition. Objective: This study aimed to investigate the association of
blood pressure with total body fat, lean mass and trunk fat in a cohort of 9-yearold children. Design: Blood pressure, BMI and body composition were
measured in 6, 863 children enrolled in the Avon Longitudinal Study of Parents
and Children (ALSPAC). Fat mass, lean mass and trunk fat were assessed
using dual-energy X-ray absorptiometry (DXA). Results: Total body fat and BMI
were strongly associated with systolic blood pressure (SBP) [β=3.50, 95%CI
3.27 to 3.74 mmHg/standard deviation (SD) and β=3.96, 95%CI 3.76 to 4.16
mmHg/SD, respectively] and weakly associated with diastolic blood pressure
(DBP) (β=1.39, 95% CI 1.22 to 1.57 mmHg/SD and β=1.37, 95% CI 1.22 to
1.52 mmHg/SD, respectively). SBP was also positively associated with lean
mass (β=3.60, 95% CI 3.22 to 3.97 mmHg/SD) and trunk fat (β=2.14, 95% CI
0.82 to 3.46 mmHg/SD, independent of total fat mass). Conclusion: Blood
pressure in 9-year-old children is independently associated with fat mass and
lean mass and, to a lesser extent, trunk fat. In this analysis, because both fat
and lean mass are associated with blood pressure, BMI predicts blood
pressure at least as well as these components of body composition.
Why is sample 2 a good abstract?

Authors







Used active voice and divided the abstract by section
Indicated the importance of their study
Included their study objective
Described the study sample and measurements
Described results
Provided appropriate conclusions
What could have improved this abstract?


Description of the analytical methods
Inclusion of methods for measure and control of
potential confounding factors
Sample 3: A Major Determinant of Recent Increases in HIV
Incidence Among Men who Have Sex with Men (MSM) in British
Columbia (BC): Deferred Initiation of Antiretroviral Therapy
Background: Recent clinical guidelines endorse deferral of highly active
antiretroviral therapy (HAART) until later in the course of HIV infection. The effect
of this change on population levels of high viremia, infectivity and, in turn, sexual
transmission of HIV is unknown. Objectives: Describe populational trends in HIV
viremia among MSM in BC in relation to a 1999 change that deferred HAART from
CD4 <500 to CD4 <200 cells/mL. Estimate relative increases in annual HIV
diagnoses among MSM attributable to this change. Methods: Linked provincial
registries provided records of all HAART, CD4 counts, and plasma HIV RNA viral
load (pVL) determinations from 1997-2003. We assessed trends in MSM with high
viremia (pVL >10 000 copies/mL) across 6-month intervals. Mathematical models
predicted relative changes in infections among MSM following introduction and
deferral of HAART. Results: The number and proportion of highly viremic MSM
declined steadily [from 443 (27.6%)] for two years following introduction of HAART.
This trend has reverted, increasing from 358 viremic MSM (17.8%) in the second
half of 1999 to 713 (26.7%) at the end of 2003; the increase occurred among men
with CD4 >200. Models predicted a 50% reduction in HIV diagnoses among MSM
from 1997-1999 but rapid 83% increase following deferral of HAART. Conclusion:
Deferral of therapy appears to be a major determinant of the 75% increase in
annual HIV diagnoses among MSM in BC from 1999-2004. Substantial increases
in HIV prevention among MSM seem warranted.
Why is sample 3 a good abstract?

Authors







Used active voice and defined acronyms
Divided the abstract by section
Indicated the importance of their study
Described their objective
Included information on their sample and study period
Described results and methods
What could have improved this abstract?


Sample size information
More detailed data collection methods
Overall Summary of Sample Abstracts






All abstracts were under the 250 word limit
All authors used active voice
Defined any acronyms used
All abstracts included background and
importance information
Described their study population, methods,
and results
Provided appropriate conclusions for their
results
Reviewing an Abstract
How to Review an Abstract?

Questions to consider when reviewing an
abstract

Is the work appropriate for the journal or
conference?




At conferences, there is usually a theme or multiple
areas of science that are sought
Journals have specific aims and goals
Is the work original?
Is the work complete?

Is the work ready to publish or present at a
conference? Are the results complete?
How to Review an Abstract?

Did the authors describe the important
features of an abstract?



Background and significance
Hypothesis
Methods




Results



Data collection methods
Sample size and population information
Analytic techniques
Demographic characteristics of sample
Significant results
Conclusions
Deciding Between a Poster or Oral
Presentation

If you are asked to determine what type of
acceptance an abstract should receive


Ask for guidelines from the conference organizers
Other considerations

What is the conference theme?


Are there special topic areas for the conference?


If so, does the abstract address the theme?
If so, does the abstract address any of these
Is the quality of the abstract above others reviewed?
Practice Abstract Review
Abstract Evaluation Guidelines

Assumptions:




Reviewing for Society for Epidemiologic Research
(SER) Conference
Areas of interest epidemiology, biostatistics, and
public health
Did the author include the important components
of an abstract
Follow the review outline provided in slides 19 and
20
Review Sample 1: Bayesian propensity score analysis
for observational data
Propensity scores analysis (PSA) involves regression adjustment for the estimated
propensity scores, and the method can be used for estimating causal effects from
observational data. However, confidence intervals may be falsely precise because PSA
ignores uncertainty in the estimated propensity scores. We propose Bayesian
propensity score analysis (BPSA) for observational studies which involve a binary
exposure, binary outcome and measured confounders. The method uses hierarchical
modelling with the propensity score as a latent variable. The first level models the
relationship between the outcome, exposure and propensity score, while the second
level models the relationship between the propensity score and measured confounders.
Markov chain Monte Carlo is used to study the posterior distribution of the exposure
effect. Our objective is to implement BPSA using computer programs and investigate
the performance of BPSA compared to PSA using Monte Carlo simulations. Synthetic
datasets, of sample size n=250, 1000, 4000, were simulated by computer for various
realistic parameter values. The datasets were analyzed using BPSA and PSA, and we
estimated the coverage probability of 80% credible intervals. The estimated coverage
probabilities ranged from 78% to 84% for BPSA, and from 42% to 82% for PSA, with
simulation standard errors less than 2%. The simulation results indicate that BPSA
provides improved inferences for exposure effects compared to PSA, in the sense that
interval estimators have the correct frequentist coverage levels under repeated
sampling of the data. We demonstrate BPSA in an observational study of the effect of
statin therapy on all-cause mortality in patients discharged from hospital following acute
myocardial infarction.
Abstract Evaluation: Review Sample 1

Is the work appropriate for the SER
conference?


Is the work original?


Yes – this describes analytic methods that can be
used for epidemiology studies
Yes - the authors developed a more appropriate
method to calculate confidence intervals
Is the work complete?

Yes – the authors simulated data to test their
hypothesis
Abstract Evaluation: Review Sample 1

Are the major components included?

Background and significance?


Hypothesis?


Yes – the authors described the need for their work and why
it is important
Yes – they proposed the use of Bayesian propensity score
analysis (BPSA) for observational studies which involve a
binary exposure, binary outcome and measured confounders
Methods?

Yes – they described how they were going to address the
hypothesis above
Abstract Evaluation: Review Sample 1

Results?


Conclusions?




Yes – the authors described their results and the accuracy
of their measures
Slightly unclear – “We demonstrate BPSA in an
observational study of the effect of statin therapy on allcause mortality in patients discharged from hospital
following acute myocardial infarction. “
No where else in the abstract do they mention the use of
these methods for the effect of statin therapy
Thus, the conclusions may not be appropriate
Overall: Good abstract and would accept it and
point out concern about conclusions to authors
Review Sample 2: Exposure to H. pylori-positive siblings
and persistence of H. pylori infection in early childhood
H.pylori infection is a common chronic infection, yet transmission pathways are
unclear; evidence suggests that siblings play a role in transmission. Transient
H.pylori infection is observed in children, but determinants of persistence are
unknown. We examine the effect of exposure to H.pylori-positive siblings on the
establishment of persistent H.pylori infection using data from the Pasitos Cohort
Study, which recruited pregnant women from maternal-child clinics in El Paso,
Texas, and Juarez, Mexico during 1998-2000 and followed 472 children after birth
to identify predictors of H.pylori infection. Infection was detected at target intervals
of 6 months in index children and younger siblings born during follow-up, using the
13C-urea breath test (UBT) corrected for variation in CO2 production. We used
proportional hazards regression to estimate hazard ratios for the effect of having
H.pylori-positive younger siblings on the rate of developing a persistent H.pylori
infection in index children with 1+ younger siblings. Persistent infection was defined
as 3 consecutive positive UBT results. We modeled two exposure definitions:
infected younger sibling (1+ younger siblings with 1+ positive UBT results);
persistently infected younger sibling (1+ younger siblings with a persistent
infection). Adjusting for mom's education (the strongest H.pylori risk factor in this
cohort), the hazard ratio was 4.0 (95% CI=1.8,8.2) for infected younger sibling and
9.3 (95% CI=3.2,26) for persistently infected younger sibling. Having H.pyloripositive younger siblings, particularly with persistent infection, was strongly
associated with developing persistent H.pylori infection in this cohort.
Abstract Evaluation: Review Sample 1

Is the work appropriate for the SER
conference?


Is the work original?


Yes – study describes an important infectious
disease
Yes – the authors are looking at an area of this
infection that is not well understood
Is the work complete?

Yes – the authors analyzed existing data to address
their question
Abstract Evaluation: Review Sample 1

Are the major components included?

Background and significance?


Hypothesis?


Yes – the authors described the need for their work and why
it is important
Yes – the authors examined the effect of exposure to
H.pylori-positive siblings on the establishment of persistent
H.pylori infection
Methods?

Yes – authors described their study population, defined their
study variables, and included the analytical methods used to
address the hypothesis
Abstract Evaluation: Review Sample 1

Results?



Conclusions?


Yes – the authors described some of their results
However, the authors did not provide the number of events
that were included in the Cox Models
Yes – authors described appropriate conclusions for the
results presented
Overall:


Good abstract
Should be accepted for presentation at the
conference
Resources



Pierson DJ. How to Write an Abstract That Will Be Accepted for
Presentation at a National Meeting, Respiratory Care, October
2004, 49(10):1206-1212
Kiipman P. How to Write an Abstract.
http://www.ece.cmu.edu/~koopman/essays/abstract.html
Sample Abstracts Obtained From:

American Journal of Epidemiology, June 1, 2006: 163 (Supplement
11).
Appendix:
Additional Abstracts
Sample A: Lifetime Recreational Physical Activity and
Breast Cancer Risk
While a number of studies have observed a reduced risk of breast cancer with
increased levels of physical activity, these findings have been inconsistent
regarding the optimal frequency, intensity, and timing of exercise. We performed a
population-based case-control study in Massachusetts, New Hampshire, and
Wisconsin. From the states' cancer registries, we enrolled 6421 women (80% of
eligible) aged 20-69 diagnosed with invasive breast cancer between 1995 and
2000. Controls (7683; 76% of eligible) were selected at random from lists of
licensed drivers and Medicare beneficiaries. In structured telephone interviews,
women reported lifetime history (age 14 to present) of recreational physical activity.
After adjustment for potential confounding risk factors using logistic regression,
women averaging greater than six hours of activity per week over their lifetime had
a reduced odds ratio (OR) of breast cancer when compared to women reporting no
recreational activity (OR 0.81, 95% CI 0.68-0.97; P trend=0.20). Analyses
considering metabolic equivalents of energy expenditure (MET) produced similar
results. While an inverse relation between physical activity averaged over the
lifetime and breast cancer risk was observed, the relation was null when limited to
activity in a single decade. The inverse association with lifetime activity was
consistent regardless of menopausal status and body mass; however, it was limited
to women with no family history of breast cancer (OR 0.75, 95% CI 0.61-0.91 for 6
vs. 0 hrs/week, P-interaction = 0.02). The results from this large study provide
further evidence that long-term recreational physical activity may reduce breast
cancer risk.
Why is sample A a good abstract?

Authors







Used active voice
Indicated why their study is important and
interesting
Gave a clear statement of purpose
Included information about the selection of cases
and controls
Discussed data collection measures
Described methods and results
Provided appropriate conclusions
Sample B: Mapping and measuring social disparities in premature
mortality: the impact of census tract poverty within and across
Boston Neighborhoods, 1999-2001
The documentation of health disparities is an important function of public health
surveillance. These disparities, typically falling along lines defined by gender,
race/ethnicity, and social class, are often visible in urban settings as geographic
disparities in health between neighborhoods. Recognizing that premature mortality is
a powerful indicator of social disparities in health, we undertook an analysis of
spatial variation in premature mortality in Boston (1999-2001) across neighborhoods
and sub-neighborhoods in relation to census tract (CT) poverty. Using a multilevel
model based framework, we estimated that the incidence of premature mortality was
1.39 times higher (95% confidence interval 1.09-1.78) among persons living in the
most economically deprived CTs (>=20% below poverty) compared to those in the
least impoverished tracts (<5% below poverty). We present maps of model-based
standardized mortality ratios that show substantial within-neighborhood variation in
premature mortality and a sizeable decrease in spatial variation after adjustment for
CT poverty. To aid interpretation, we also map smoothed age-standardized rates that
can be compared to externally published rates. Additionally, we present maps of the
model-based population attributable fraction that show that in some of Boston's
poorest neighborhoods, the proportion of excess deaths associated with CT poverty
reaches 25-30%. We recommend that these methods be incorporated into routine
analyses of public health surveillance data to highlight continuing social disparities in
premature mortality.
Why is sample B a good abstract?

Authors






Used active voice and defined acronyms
Indicated the importance of their study
Described their objective and their analytic strategy
(spatial mapping)
Included the geographic area
Described the maps generated
What could have improved this abstract?

Explanation of their results and how to interpret the
maps