2.5.1 Structured Abstracts
For reports of original data, systematic reviews (including meta-analyses), and clinical reviews, structured abstracts that use predetermined sideheads are recommended. Specific advice taken from JAMA’s Instructions for Authors,1 adapted from Haynes et al,8 is given below. Note that Design, Setting, and Patients or Other Participants may be combined depending on the description. If no intervention was performed, that sideheading may be omitted. Many journals limit the number of words to 250, but some (such as JAMA) allow 300 for reports of original data and for systematic reviews.
Structured Abstracts for Reports of Original Data.
In reports of original data, include an abstract of no more than 300 words using the following headings: Context, Objective, Design, Setting, Patients (or Participants), Interventions (include only if there are any), Main Outcome Measure(s), Results, and Conclusions. For brevity, phrases rather than complete sentences may be used. Include the following content in each section:
Context: Begin the abstract with a sentence or two explaining the clinical (or other) importance of the study question.
Objective: State the precise objective or study question addressed in the report (eg, “To determine whether…”). If more than 1 objective is addressed, indicate the main objective and state only key secondary objectives. If an a priori hypothesis was tested, state that hypothesis.
Design: Describe the basic design of the study. State the years of the study and the duration of follow-up. If applicable, include the name of the study (eg, the Framingham Heart Study).
Setting: Describe the study setting to assist readers to determine the applicability of the report to other circumstances, for example, general community, a primary care or referral center, private or institutional practice, or ambulatory or hospitalized care.
Patients or Other Participants: State the clinical disorders, important eligibility criteria, and key sociodemographic features of patients. Provide the numbers of participants and how they were selected (see below), including the number of otherwise eligible individuals who were approached but refused. If matching is used for comparison groups, specify the characteristics that are matched. In follow-up studies, indicate the proportion of participants who completed the study. In intervention studies, provide the number of patients withdrawn because of adverse effects. For selection procedures, use these terms, if appropriate: random sample (where random refers to a formal, randomized selection in which all eligible individuals have a fixed and usually equal chance of selection); population-based sample; referred sample; consecutive sample; volunteer sample; convenience sample.
Intervention(s): Describe the essential features of any interventions, including their method and duration of administration. Name the intervention by its most common clinical name, and use nonproprietary drug names.
Main Outcome Measure(s): Indicate the primary study outcome measurement(s) as planned before data collection began. If the manuscript does not report the main planned outcomes of a study, state this fact and indicate the reason. State clearly whether the hypothesis being tested was formulated during or after data collection.
Results: Provide and quantify the main outcomes of the study, including confidence intervals (eg, 95%) or P values. For comparative studies, express the differences between groups with confidence intervals. Explain outcomes or measurements unfamiliar to a general medical readership. Declare important measurements not presented in results. As relevant, indicate whether observers were blinded to patient groupings, particularly for subjective measurements. If differences for the major study outcome measure(s) are not significant, state the clinically important difference sought and provide the confidence interval for the difference between the groups. When risk changes or effect sizes are given, indicate absolute values. Approaches such as number needed to treat to achieve a unit of benefit are encouraged when appropriate; reporting of relative differences alone is insufficient. For studies of screening and diagnostic tests, report sensitivity, specificity, and likelihood ratio. If predictive value or accuracy is given, provide prevalence or pretest likelihood as well. For all randomized controlled trials, include the results of intention-to-treat analysis, and for all surveys include response rates.
Conclusions: Provide only conclusions of the study directly supported by the results, taking into account the limitations (eg, observational study, selected population), along with implications for clinical practice, avoiding speculation and overgeneralization. Indicate whether additional study is required before the information should be used in usual clinical settings. Give equal emphasis to positive and negative findings of equal scientific merit.
Trial Registration: For clinical trials, provide the name of the trial registry, registration number, and URL of the registry.
Structured Abstracts for Systematic Reviews (Including Meta-analyses).
In manuscripts reporting the results of meta-analyses, include an abstract of no more than 300 words using the following headings: Context, Objective, Data Sources, Study Selection, Data Extraction, Data Synthesis, and Conclusions. In the text of the manuscript, include a section describing the methods used for data sources, study selection, data extraction, and data synthesis. Follow each heading with a brief description:
Context: Provide a sentence or two explaining the importance of the review question.
Objective: State the precise primary objective of the review. Indicate whether the review emphasizes factors such as cause, diagnosis, prognosis, therapy, or prevention and include information about the specific population, intervention, exposure, and tests or outcomes that are being reviewed.
Data Sources: Succinctly summarize data sources, including years searched. Include in the search the most current information possible, ideally conducting the search several months before the date of manuscript submission. Potential sources include computerized databases and published indexes, registries, abstract booklets, conference proceedings, references identified from bibliographies of pertinent articles and books, experts or research institutions active in the field, and companies or manufacturers of tests or agents being reviewed. If a bibliographic database is used, state the exact indexing terms used for article retrieval, including any constraints (for example, English language or human subjects). If abstract space does not permit this level of detail, summarize sources in the abstract including databases and years searched, and place the remainder of the information in the “Methods” section of the text.
Study Selection: Describe inclusion and exclusion criteria used to select studies for detailed review from among studies identified as relevant to the topic. Under details of selection include particular populations, interventions, outcomes, or methodological designs. Specify the method used to apply these criteria (for example, blinded review, consensus, multiple reviewers). State the proportion of initially identified studies that met selection criteria.
Data Extraction: Describe guidelines used for abstracting data and assessing data quality and validity (such as criteria for causal inference). State the method by which the guidelines were applied (eg, independent extraction by multiple observers).
Results: State the main results of the review, whether qualitative or quantitative, and outline the methods used to obtain these results. For meta-analyses, state the major outcomes that were pooled and include odds ratios or effect sizes and, if possible, sensitivity analyses. Accompany numerical results by confidence intervals, if applicable, and exact levels of statistical significance. For evaluations of screening and diagnostic tests, include sensitivity, specificity, likelihood ratios, receiver operating characteristic curves, and predictive values. For assessments of prognosis, summarize survival characteristics and related variables. State the major identified sources of variation between studies, including differences in treatment protocols, protocols, co-interventions, confounders, outcome measures, length of follow-up, and dropout rates.
Conclusions: Clearly state the conclusions and their applications (clinical or otherwise), limiting interpretation to the domain of the review.
Structured Abstracts for Clinical Reviews.
For Clinical Review articles, include an abstract of no more than 250 words with the following sections: Context, Evidence Acquisition, Evidence Synthesis, and Conclusions.
Context: Include 1 or 2 sentences describing the clinical question or issue and its importance in clinical practice or public heath.
Evidence Acquisition: Describe the data sources used, including the search strategies, years searched, and other sources of material, such as subsequent reference searches of retrieved articles. Explain the methods used for quality assessment and the inclusion of identified articles.
Results: Address the major findings of the review of the clinical issue or topic in an evidence-based, objective, and balanced fashion, emphasizing the highest-quality evidence available.
Conclusions: Clearly state the conclusions to answer the questions posed if applicable, basing the conclusions on available evidence, and emphasize how clinicians should apply current knowledge.