Structured abstracts: narrative review

Resumos estruturados: revisão narrativa

SCIENTIFIC COMMUNICATION

Structured abstracts. Narrative review

Resumos estruturados. Revisão narrativa

Carlos Alberto Guimarães

Associate Professor, Department of Surgery, School of Medicine, Federal University of Rio de Janeiro, Brazil. Editor, Journal of the School of Medicine, Teresópolis, Brazil. Research fellow of "Núcleo de Comunicação Científica em Cirurgia (NCCC) - Sobradpec

ABSTRACT

PURPOSE: To summarize the main findings from research on structured abstracts.

METHODS: A narrative review of all the relevant papers known to the author was conducted.

RESULTS: Authors and readers judged the structured abstracts to be more useful than traditional ones. In 1987 the Ad Hoc Working Group for Critical Appraisal of the Medical Literature proposed guidelines for informative seven-headings abstracts. In 1990 Haynes et al. reconsidered the structured abstract of clinical research and review articles and proposed revised guidelines. Nowadays, most abstracts are informative, and the most commonly used structure is IMRAD (Introduction, Methods, Results And Discussion) format.

CONCLUSIONS: There are many variations in the structured-abstract formats prescribed by different journals. But even in recent years, not all abstracts of original articles are structured. More research is needed on a number of questions related to the quality and utility of structured abstracts.

Key words: Abstracting and indexing. Review literature. Peer review

RESUMO

OBJETIVO: Sintetizar os principais resultados das pesquisas sobre resumos estruturados..

MÉTODOS: Uma revisão narrativa de todos os estudos, considerados relevantes pelo autor, foi realizada.

RESULTADOS: Os autores e os leitores julgaram que os resumos estruturados são mais úteis que os tradicionais. Em 1987, o Ad Hoc Working Group for Critical Appraisal of the Medical Literature propôs diretrizes para a elaboração de resumos informativos com sete seções. Haynes e col., em 1990, reestudaram os resumos estruturados para a pesquisa clínica e para os artigos de revisão e propuseram novas diretrizes. Atualmente, a maioria dos resumos é informativa e a estrutura mais utilizada é aquela do formato IMRAD (Introdução, Métodos, Resultados e Discussão)

CONCLUSÃO: Há muita variação nos formatos dos resumos estruturados solicitados pelo vários periódicos. Contudo, mesmo nos anos mais recentes, nem todos os resumos dos artigos originais são estruturados. Necessita-se de mais pesquisas relacionadas à qualidade e à utilidade dos resumos estruturados.

Descritores: Resumos e indexação. Literatura de revisão. Comissão de avaliação de exercício profissional

Types of abstracts

Since its origin in 1665, the scientific paper has been through many changes, but method description only developed during the second half of the 19th century. In the course of the 20th century, the formal established Introduction, Methods, Results, And Discussion (IMRAD) structure was adopted.¹ The proposed structured abstract, that is, abstract that describe a study using content headings, provided more informative content. Except for the title, the abstract is the part of a scientific paper that will be read by the most people.² The basic purpose of abstracts is to summarize the contents of articles so that readers can decide whether to read them. It is the only part of an article that many journals will make accessible through search engines.³

Indicative or descriptive abstracts deal with the contents of the paper, whereas informative abstracts tell us about the objectives, methods, results and conclusions. Nowadays, most abstracts are informative, and the most commonly used structure is IMRAD format.⁴

Most clinical journals did not include abstracts with articles until the late 1960s. Then, the Journal of the American Medical Association and the Canadian Medical Association Journal moved the summary and conclusions of papers to the beginning (Table 1). The presence of an abstract as the introduction to medical reports was of enormous assistance to computerized services.⁵

In 1987 the Ad Hoc Working Group for Critical Appraisal of the Medical Literature proposed guidelines for informative seven-headings abstracts. These guidelines were prepared by Haynes and colleagues at McMaster University, Canada and then with 358 persons from 18 countries (four Brazilian members: Deolinda Martins, L. dos Santos Neto, M. G. Pereira e César G. Victora) (Table 2).^7,8 The structured proposal was for original articles dealing with the cause, course, diagnosis, and treatment of health care problems. It did not include articles such as editorials, reviews, case reports, etc. Table 3 shows an example of these guidelines.

In Brazil 1988 the Revista Paulista de Medicina suggested the authors to use this seven-sections abstract when reporting clinical trials.¹⁰ Also in this year, it was proposed a structured abstract for reviews with the headings: Objective, Data sources, Methods of study selection, Data extraction and synthesis, and Conclusions (Table 4). Table 5 shows an example of these six guidelines.

The proposed structured abstract for reviews has many advantages: 1. readers can identify reviews that are relevant; 2. bias can be detected; 3. results and conclusions can be critically appraised; 4. authors are given a framework that will help them present their results; 5. vital elements of a review are identified; 6. computerized literature searches will be possible, and 7. improved peer review processes may result.¹¹

In 1990, Haynes et al. reconsidered the structured abstract of clinical research and review articles (including meta-analysis) and proposed revised guidelines. They emphasized that the structured abstract should be prepared by the authors before the manuscript is peer reviewed, to ensure that it accurately reflects the article´s contents (Table 6).⁵Tables 7 and 8 show examples of these guidelines for an original and a review article.

Structured abstracts (< 250 words) were designed to meet three objectives of informing readers better, improving search retrieval, or facilitating peer review. They can be adapted for most investigations, including systematic reviews, conference articles and papers reporting laboratory studies. They were not expanded to cover case reports, studies of tissues or animals, and opinion articles.⁵

Parts of the abstract can be written in phrases rather than completed sentences. (For example: 2. Design. Double-blind randomized trial, rather than 2. Design. The study was conduted as a double-blind, randomized trial.) This technique facilitates selection scanning and allows more information per unit of space.⁵

The advantage of structured abstracts is that it is easier to understand the text written in shorter paragraphs. They help authors not to omit relevant data, and reveals methodological errors. Structured abstracts in English are also convenient to non-English authors.⁴

Structured abstracts contain the most significant data from the paper, and some use them as primary source of information. Writing a good abstract requires considerable attention to details. Very often the decision whether the paper is going to be accepted for publication or not, depends on the title and abstract. The author has about 15 seconds to convince readers to read the rest of the paper. Only about 50% of the research projects submitted as conference abstracts will eventually be published as full articles.⁴

Abstracts mostly written in the same language as the article, but are also translated into other languages. Abstracts should be written in the past tense and in third person singular. Omit all references to the literature and the tables or figures, and omit obscure abbreviations and acronyms.⁴

In 1996 July the editors of the Annals of Internal Medicine realized that the structured abstract did not provide adequate context for a study, and asked authors to add a Background section (Table 9).³

Finally, in 2004 Mar the editors of the Annals of Internal Medicie proposed a new type of structured abstract (a critical one). They became concerned that abstracts may give readers the impression that the research has no flaws. In the structured abstract, they included a new section on Limitations, located immediately before Conclusions, a spot that should attract the attention of the. Reflecting on the limitations of a study can help readers decide whether results apply to their patients.³Table 10 shows an example of a ten-sections structured abstract with Limitations.

Research

Tadio et al. reported a blind, observational study of nonstructured and structured abstracts of original articles in the British Medical Journal, the Canadian Medical Association Journal and the Journal of the American Medical Association. The quality of 300 abstracts was measured against objective criteria, and the findings supported recommendations that suggest the use of structured abstracts.¹⁷

The number of Medline journal publishing structured abstracts increase between 1989 and 1991. Articles with structured abstracts had more access points (Medical Subject Heading [MeSH®] terms and text words) than MEDLINE articles as a whole.¹⁸

Timmer et al. have developed a reliable and applicable instrument for the evaluation of the quality of abstracts. While most useful for clinical trials, limitations may apply for its use in basic science. It may be helpful as a checklist for the preparation of abstracts or as an instrument to compare abstract quality between meetings. Other possible applications include the adjunct use in abstract peer review.¹⁹

The results of studies comparing tradicional abstracts with structured abstracts, suggest that the later: contain more information; are easier to read and to search; are easier to recall; facilitate peer review for conference proceedings; are welcomed by readers and by authors. However, there have been some qualifications: take up more space; sometimes have confusing typographic layouts; and may have the same sorts of omissions and distortions.²⁰

A cross-sectional study has measured the frequency of articles written under the IMRAD format from 1935 to 1985 in a randomly selected samples of articles published in four leading journal in Internal Medicine: the British Medical Journal, JAMA, The Lancet, and the New England Journal of Medicine. The IMRAD structure began to be used in the 1940s. In the 1970s, it reached 80% and, in the 1980s, was the only pattern adopted by these journals for original papers.²¹

Even in recent years, not all abstracts of original articles are structured. Patterns of abstracts recently (2001 Jan) published in the ''Medicine, General and Internal'' top thirty journals (ISI 2000 impact factors) were examined. Among 304 original articles that included abstracts, 188 (61.8%) had structured and 116 (38.2%) had unstructured abstracts. One hundred twenty-five (66.5%) of the abstracts used the IMRAD format, and 63 (33.5%) used the 8-heading format proposed by Haynes et al. Twenty-one journals requested structured abstracts in their instructions to authors; 8 journals requested the 8-heading format; and 1 journal requested it only for intervention studies.²²

ICMJE position

The International Committee of Medical Journals Editors updated the Uniform Requirements for Manuscripts Submitted to Biomedical Journals (followed by most medical journals) last 2006 February. In Section IV.A.4 (Abstracts and Key Words) it is stated: The abstract should provide the context or background for the study and should state the study's purposes, basic procedures (selection of study subjects or laboratory animals, observational and analytical methods), main findings (giving specific effect sizes and their statistical significance, if possible), and principal conclusions. It should emphasize new and important aspects of the study or observations. Because abstracts are the only substantive portion of the article indexed in many electronic databases, and the only portion many readers read, authors need to be careful that abstracts reflect the content of the article accurately. Unfortunately, many abstracts disagree with the text of the article. The format required for structured abstracts differs from journal to journal, and some journals use more than one structure; authors should make it a point prepare their abstracts in the format specified by the journal they have chosen.²³

Conclusions

Authors and readers judge the structured abstracts to be more useful than traditional ones. There are many variations in the structured-abstract formats prescribed by different journals. Nowadays, the most commonly used structure is IMRAD. But even in recent years, not all abstracts of original articles are structured. More research is needed on a number of questions related to the quality and utility of structured abstracts.

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• ²³
  International Committee of Medical Journals Editors. Uniform Requirements for Manuscripts Submitted to Biomedical Journals [monograph on the Internet]. Philadelphia: ICMJE; 2006 [cited 2006 Jun 8]. Available from: http://www.icmje.org/

Publication Dates

• Publication in this collection
  20 Sept 2006
• Date of issue
  Aug 2006