What are structured abstracts?
A structured abstract is an abstract with distinct, labeled sections (e.g., Introduction, Methods, Results, Discussion) for rapid comprehension (see Figure 1).
Figure 1: PubMed Abstract Display for a Structured Abstract
What kinds of structures are used?
Standardized formats for structured abstracts have been defined for original research studies, review articles and clinical practice guidelines (1,2). The IMRAD format (INTRODUCTION, METHODS, RESULTS, DISCUSSION), a defacto standard that reflects the process of scientific discovery (3), is commonly used as a structure for journal abstracts (4,5). The CONSORT (Consolidated Standards of Reporting Trials) Group has issued a guideline for reporting randomized controlled trials (RCTs) in journal and conference abstracts by developing a minimum list of essential items that authors should consider when reporting the main results of a RCT in any journal or conference abstract. CONSORT for Abstracts recommends that abstracts relating to RCTs have a structured format (6).
Why use structured abstracts?
Structured abstracts have several advantages for authors and readers. These formats were developed in the late 1980s and early 1990s to assist health professionals in selecting clinically relevant and methodologically valid journal articles. They also guide authors in summarizing the content of their manuscripts precisely, facilitate the peer-review process for manuscripts submitted for publication, and enhance computerized literature searching (1,2).
The International Committee of Medical Journal Editors (ICMJE, of which NLM is a sitting member), whose "Uniform Requirements for Manuscripts Submitted to Biomedical Journals" document provides general guidelines for the format of manuscripts submitted to journals, endorses the use of structured abstracts, especially for original research and systematic reviews. ICMJE does acknowledge the format required for structured abstracts differs from journal to journal and that some journals use more than one structure (7).
The National Library of Medicine® (NLM®) studied structured abstracts in MEDLINE® from 1989-1991 and published an article characterizing structured abstracts by examining the occurrence of structured abstracts; characteristics of MEDLINE records with structured abstracts; editorial policies of selected MEDLINE journals, and a random sample of structured abstracts (8). Additional NLM research on structured abstracts revealed that about a quarter of all abstracts currently added to MEDLINE include section labels such as BACKGROUND, OBJECTIVE, METHODS, RESULTS, and CONCLUSIONS (9). More information about NLM research on structured abstracts including technical details for the NLM implementation of structured abstracts can be found at http://structuredabstracts.nlm.nih.gov.
How are structured abstracts formatted in PubMed?
NLM uses all uppercase letters followed by a colon and space for the labels that appear in structured abstracts in MEDLINE/PubMed® citations (see Figure 1).
How can I search for structured abstracts in PubMed?
In a PubMed search box, type:
This search retrieves over two million citations. (Note: This search does not include citations with the status of publisher, i.e., publisher [sb].)
- Haynes RB, Mulrow CD, Huth EJ, Altman DG, Gardner MJ. More informative abstracts revisited. Ann Intern Med. 1990 Jul 1;113(1):69-76. PubMed PMID: 2190518. Available from: http://www.annals.org/content/113/1/69.full.pdf+html.
- Hayward RS, Wilson MC, Tunis SR, Bass EB, Rubin HR, Haynes RB. More informative abstracts of articles describing clinical practice guidelines. Ann Intern Med. 1993 May 1;118(9):731-7. PubMed PMID: 8460861. Available from: http://www.annals.org/cgi/content/full/118/9/731.
- Sollaci LB, Pereira MG. The introduction, methods, results, and discussion (IMRAD) structure: a fifty-year survey. J Med Libr Assoc. 2004 Jul;92(3):364-7. PubMed PMID: 15243643; PubMed Central PMCID: PMC442179.
- Nakayama T, Hirai N, Yamazaki S, Naito M. Adoption of structured abstracts by general medical journals and format for a structured abstract. J Med Libr Assoc. 2005 Apr;93(2):237-42. PubMed PMID: 15858627; PubMed Central PMCID: PMC1082941.
- Kulkarni H. Structured abstracts: still more. Ann Intern Med. 1996 Apr 1;124(7):695-6. PubMed PMID: 8607606. Available from: http://www.annals.org/cgi/content/full/124/7/695-a.
- Hopewell S, Clarke M, Moher D, Wager E, Middleton P, Altman DG, Schulz KF; CONSORT Group. CONSORT for reporting randomized controlled trials in journal and conference abstracts: explanation and elaboration. PLoS Med. 2008 Jan 22;5(1):e20. PubMed PMID: 18215107; PubMed Central PMCID: PMC2211558.
- International Committee of Medical Journal Editors. Uniform Requirements for Manuscripts Submitted to Biomedical Journals: Writing and Editing for Biomedical Publication. [updated 2010 Apr; cited 2010 Aug 2]. Available from: http://www.icmje.org.
- Harbourt AM, Knecht LS, and Humphreys BL. Structured abstracts in MEDLINE, 1989-1991. Bull Med Libr Assoc. 1995 Apr; 83(2):190-5. PubMed PMID: 7599584; PubMed Central PMCID: PMC226026.
- Ripple AM, Mork JG, Knecht LS, Humphreys BL. A retrospective cohort study of structured abstracts in MEDLINE, 1992-2006. J Med Libr Assoc. 2011 Apr;99(2):160-3. PubMed PMID: 21464855; PubMed Central PMCID: PMC3066587.