The Structured Abstract

1
The Structured Abstract

• Session 5
• C507
• Scientific Writing

2
Functions of an Abstract

• Provide the reader with information regarding the
  research performed
• This may determine if the paper is read
• Serves as a miniature of the research

3
Prose Abstract

• Until the last few years, and still in some
  cases, abstracts were prepared as a short prose
  summary of the article
• But, there was trouble in paradise

4
The Problem

• Squires BP. Abstracts the need for improvement.
  Can Med Assoc J 1991144421
• 56 of abstracts did not report the technical
  design of the study
• 79 did not describe how subjects were selected
• 86 did not address limitations
• 93 made no recommendations for future study

5
The Answer

• The purpose of a structured abstract is to ensure
  that all the appropriate information is included
  in the abstract so that readers are provided full
  details of the work, which can save cost and time
  in their own work.

6
A Bit of History

• Initial impetus came from Brian Haynes of the Ad
  Hoc Working Group for Critical Appraisal of the
  Medical Literature
• Ad Hoc Working Group for Critical Appraisal of
  the Medical Literature. A proposal for more
  informative abstracts of clinical articles. Ann
  Intern Med 1987106598-604

7
And a Bit More

• In 1990, Haynes and colleagues assessed the first
  few years of the use of structured abstracts
• Reporting errors were decreased but not absent
• Support from the scientific community was
  widespread

8
Instructions

• No more than 250 words
• Use the following general headings
• Objective
• Design
• Setting
• Patients
• Interventions

9
Instructions (Cont.)

• Main Outcome Measures
• Main Results
• Conclusions

10
Objective

• The abstract should begin with a clear statement
  of the precise objective or question addressed in
  the report. If more than one objective is
  addressed, the main objective should be indicated
  and only key secondary objectives stated. If a
  priori hypothesis was tested, it should be stated.

11
Design

• The basic design of the study should be
  described. The duration of follow-up, if any,
  should be stated.
• As many of the following terms as apply should be
  used

12
For Intervention Studies

• Randomized controlled trial
• Non-randomized controlled trial
• Double-Blind
• Placebo Control
• Crossover Trial
• Before-After Trial

13
For Studies of Screening and Diagnostic Tests

• Criterion standard (that is, a widely accepted
  standard with which a new or alternative test is
  being compared this is preferred to the term
  gold standard.)
• Blinded comparison
• Masked comparison

14
For Studies of Prognosis

• Inception cohort (subjects assembled at a similar
  and early time in the course of the disorder and
  followed thereafter)
• Cohort (subject followed forward in time, but not
  necessarily from a common starting point)
• Validation cohort or sample (if study involves
  modeling of clinical predictions)

15
For Studies of Causation

• Randomized Controlled Trial
• Cohort
• Case-Control
• Survey (not cross-sectional study.)

16
For Descriptions of the Clinical Features of
Medical Disorders

• Survey
• Case Series

17
For Studies that Include a Formal Economic
Evaluation

• Cost-Effectiveness Analysis
• Cost-Utility Analysis
• Cost-Benefit Analysis
• For new analyses of existing data sets, the data
  set should be named and the basic study design
  disclosed

18
Setting

• To assist readers to determine the applicability
  of the report to their own clinical
  circumstances, the study setting should be
  described.
• Of particular importance is whether the setting
  is the general community, a primary care or
  referral center, private or institutionalized
  practice or ambulatory or hospitalized care.

19
Patients or Other Participants

• The clinical disorders, important eligibility
  criteria and key sociodemographic features of
  patients should be stated.
• The number of participants and how they were
  selected should be provided, including the number
  of otherwise eligible subjects who were
  approached but refused.

20
Patients or Other Participants

• If matching is used for comparison groups,
  characteristics that are matched should be
  specified.
• In follow-up studies, the proportion of
  participants who completed the study must be
  indicated.
• In intervention studies, the number of patients
  withdrawn for adverse effect should be given.

21
Patients or Other Participants

• For selection procedures, these terms should be
  used
• Random sample
• Population-based sample
• Referred sample
• Consecutive Sample
• Volunteer Sample
• Convenience sample

22
Intervention(s)

• The essential feature of any intervention should
  be described, including their method and duration
  of administration.
• The intervention should be named for its most
  common clinical name (usually this is so for
  drugs, but can also be true for specific
  chiropractic techniques).

23
Main Intervention Measures

• The primary outcome measurements should be
  indicated as planned before data collection
  began.
• If the paper does not emphasize the main planned
  outcomes of a study, this fact should be stated
  and the reason indicated

24
Main Intervention Measures

• If the hypothesis being reported was formulated
  during or after data collection, this information
  should be clearly stated.

25
Results

• The main results of the study should be given.
• Measurements that require explanation for the
  expected audience of the article should be
  defined.
• Important measurements not included in the
  presentation of results should be declared.

26
Results

• It should be indicated whether observers were
  blinded to patient groupings, particularly for
  subjective measurements.
• Where possible, results should be accompanied by
  confidence intervals, (ie, 95) and the exact
  level of statistical significance.

27
Results

• When risk changes or effect sizes are given,
  absolute values should be indicated so that the
  reader can determine the absolute as well
  relative impact of the finding.

28
Results

• Where appropriate, studies of screening and
  diagnostic tests should use the terms
  sensitivity, specificity and likelihood ratio
• If predictive values or accuracy are given,
  prevalence or pretest likelihood should be given
  as well.

29
Results

• No data should be reported in the abstract that
  do not appear in the rest of the article.

30
Conclusion

• Only those conclusions of the study that are
  directly supported by the evidence reported
  should be given, along with their clinical
  application (avoiding speculation and
  over-generalization) and an indication whether
  additional study is required before the
  information should be used in usual clinical
  settings.

31
A Few General Comments

• For brevity, you do not need to use full
  sentences in all cases and for all entries.
• This allows for more information to be provided
  per unit of space.

32
Structured Abstract for Literature Reviews

• Normal organization is
• Objective
• Data Source
• Study Selection
• Data Extraction
• Data Synthesis
• Conclusions

33
Objective

• The focus of this statement should be guided by
  whether the review emphasizes factors such as
  cause, diagnosis, prognosis, therapy or
  prevention,
• It should include information about the specific
  population, intervention or exposure and test or
  outcome being reviewed.

34
Data Sources

• Provide a summary of the data sources you used,
  along with any time restrictions.
• When a data base is used, the exact indexing
  terms used for article retrieval should be
  stated, including constraints (ie, English
  language only).

35
Study Selection

• Describe the criteria used to select studies for
  detailed review from among studies identified as
  relevant to the topic.
• Details should include particular populations,
  interventions, outcomes or methodological designs.

36
Data Extraction

• Guidelines used for abstracting data and
  assessing data quality and validity should be
  described.
• The method by which the guidelines were applied
  should be stated, for example, independent
  extraction by multiple observers.

37
Data Synthesis

• The main results of the review, whether
  qualitative or quantitative, should be stated.
• Methods used to obtain these results should be
  outlined.

38
Data Synthesis

• Meta-analyses should state the major outcomes
  that were pooled and include odds ratios or
  effect sizes, and if possible, sensitivity
  analyses.
• Numerical results should be accompanied by CIs,
  if applicable, and exact levels of statistical
  significance.

39
Data Synthesis

• Evaluations of screening and diagnostic tests
  should address issues of sensitivity,
  specificity, likelihood rations, receiver
  operating characteristic curves and predictive
  values.
• Assessments of prognosis could include summaries
  of survival characteristics and related variables.

40
Data Synthesis

• Major identified sources of variation between
  studies should be stated, including, for example,
  differences in treatment protocols,
  cointerventions, confounders, outcome measures,
  length of follow-up and drop-out rates.

41
Conclusion

• The conclusions and their applications should be
  clearly stated, limiting generalizations to the
  domain of the review.
• The need for new studies may be stated.

42
Abstract for a Case Report

• General headings include
• Objective
• Clinical Features
• Intervention and Outcome
• Conclusion

43
Objective

• Clearly state what you expect the reader to take
  from reading your paper
• Could be to describe an interesting case, an
  unusual diagnosis, a case with an interesting
  response to therapy, etc.

44
Clinical Features

• List only those clinical features that are
  specific to the case do not provide a list of
  normal findings
• Provide the reason why the patient sought care
• Where possible, provide a diagnosis

45
Intervention and Outcome

• Provide detail as to the treatment offered.
• Detail should be sufficient for the reader to
  understand what was done
• Provide detail as to the patient response list
  outcome measures used and changes that occurred

46
Intervention and Outcome

• Where the purpose of the case does not deal
  directly with a response to care (ie. a case that
  reports an unusual radiographic finding) provide
  information about referral, where appropriate.

47
Conclusion

• Case reports cannot be generalized beyond the
  results from the single case be cautious not to
  discuss effectiveness, efficiency or make broad
  generalizations
• Be sure that your conclusion is supported by
  evidence from the case