The Abstract stands independently and is referred by a reader to help determine the relevance of the complete manuscript—however, this only applies to well-written abstracts. A well-written one increases the chances of publication and boosts the impact factor.
Regardless of the manuscript type, an abstract has the following four sections
- Study objective or Background
- Study design and methods
- Primary results
- Principal Conclusions
Guidelines for Writing Abstracts of Original Data Manuscripts: Randomized Controlled Trial, Cross Over Trial, Cohort Study, Case-Control Study, Case Series, and Cross-Sectional Study
Study objective and Background
- Context (Background): It summarizes the rationale of the study, providing the clinical reason for the study question (hypothesis). Just a sentence or two is sufficient
- Objective: The precise objective must be stated. If more than 1 objective is addressed, clearly mention the main objective; the secondary objectives need only a mention.
Example: The aim of this study was to evaluate the efficacy and safety of centamab combined with dinplatin/daxine as a first-line treatment in patients with unresectable/metastatic gastric or gastroesophageal junction adenocarcinoma.
- The study design is the first component of the methods section: Name the study design and the duration of the follow-up period
- Intervention studies: randomized control trial; nonrandomized controlled trial; double-blind; placebo-controlled; crossover trial; before-after trial
- Studies involving screening and diagnostic tests: criterion standard is a widely accepted standard with which a new or alternative test is being compared, so it is called the gold standard. This must be mentioned clearly. There may be studies with blinded or masked comparison.
- For studies of prognosis: inception cohort (subjects assembled at a similar or early time in the course of the disorder and followed thereafter); cohort (subjects observed forward in time, but not necessarily from a common starting point); validation cohort or validation sample if the study involves the modeling of clinical predictions
- For studies of causation: randomized control trial; cohort; case-control; a survey that is also known as a cross-sectional study
- For a description of the clinical features of medical disorders: survey; case-series
- For studies that involve formal economical evaluation: cost-effective 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 should be disclosed.
Example: Female patients with intestinal bowel syndrome and diarrhea were enrolled in a randomized, open-label study to evaluate the healthcare resource use, quality of life, and productivity following treatment with honctomycin versus traditional therapy for 24 weeks.
- The setting is the second component of the Methods section: Study setting must be mentioned. Some of the commonly used study settings are as follows: general community, a primary care or referral center, private or institutional practice, or ambulatory or hospitalized care.
- Patients or Other Participants: It is the third component of the Methods Section–The clinical disorders, important eligibility criteria, and key sociodemographic features of patients must be stated.
- Mention the number of participants
- The criteria used to select the participants
- Eligible subjects who refused to participate must also be mentioned
- To do the matching for group comparison (experimental and control group characteristics)
Matching characteristics must be specified.
For the follow-up studies:
Mention the proportion of patients completing the follow-up period.
For intervention studies:
Mention the patients who withdrew due to adverse reaction.
Selection procedure terms that are commonly used are as follows: random sample, population-based sample, referred sample, consecutive sample, volunteer sample, convenience sample.
Selection procedure terms indicate the generalizability of the study.
- Intervention: Mention the method and duration of administration. Common clinical name and common synonyms must be mentioned. In the case of a drug, the brand name may also be provided.
Example: We randomly assigned 525 patients with osteoarthritis of the knee to receive azumumab (administered at a dose of 10, 25, 50, 100, or 200 µg per kilogram of body weight) or placebo on days 1 and 56.
- Main outcome Measures: The primary study outcome measurement(s) should be indicated; these were decided before collecting study data. In the case of studies that do not emphasize planned study outcomes, we need to mention this observation and the associated reason. In case the hypothesis is formulated during or after data collection, then this piece of information must be clearly mentioned.
Example (In a study of neoadjuvant endocrine therapy for breast cancer): The primary endpoint will be clinical response rate, as measured by calipers. Secondary endpoints include pathologic complete response rate, breast-conserving rate, change in Ki67 expression, breast density change, and toxicity profile.
Example summarizing 4, 5, and 6
This randomized-controlled pilot study was conducted at 19 acute stroke and rehabilitation centers. Forty-seven ischemic stroke patients with at least leg motor weakness admitted within 24 hours of onset were randomly assigned to receive continuous intravenous infusions of edavorone (30 mg) twice daily for 3 days (short-term group) or 10-14 days (long term group)
Mention the main results of the study, including the ones requiring an explanation for the expected audience. As the results are meant to be indexed in electronic format, TABLE FORMAT IS NOT USED for presentation.
Blinding of observers included inpatient groups must be mentioned for subjective measurements.
A subjective measurement depends on the observers’ perspective therefore the blindness of the study subject is critical for a non-biased decision, for example, evaluation or staging of radiological (such as CT or MR) exam results by a pathologist.
Mention the confidence interval and exact level of statistical significance as appropriate. In comparative studies, confidence interval relates to differences among groups. When there are no significant differences in the major study outcome measures, mention the clinically important difference. Moreover, the confidence interval for the difference between the groups must be mentioned.
In the case of risk and effect sizes, absolute values must only be reported. The reader can assess the relative value of the finding.
Reporting of relative differences is inappropriate.
In case of screening and diagnostic tests, mention the “sensitivity”, “specificity,” and “likelihood ratio”.
If you mention predictive values or accuracy, then you also need to mention prevalence or pretest likelihood.
DO NOT REPORT ANY DATA THAT DOES NOT APPEAR IN THE MAIN MANUSCRIPT.
The primary efficacy outcome occurred in 26 of 1502 patients (1.8%) in the group receiving huckdamycin and 44 of 1500 patients (3.0%) in the placebo group. The incidence of each component of the primary efficacy outcome was significantly reduced in the huckdamycin group as compared with the placebo group, except for the outcome of death (0.1% in both groups). The rate of pulmonary embolism or deep-vein thrombosis was 85% lower in the huckdamycin group than in the placebo group (0.2% vs 1.3%; 95% CI, 50 to 95; P < 0.001). Similar risk reductions were observed at day 77. Major bleeding occurred in one patient in each group. The incidence of serious adverse events was 0.7% with huckdamycin and 1.1% with placebo.
Mention only those conclusions that have been supported by evidence in the manuscript. Mention their clinical application and also indicate whether additional studies must be conducted before using this information in actual clinical practice.
Both positive and negative findings have to be reported with equal importance.
For example Design: Double-blind randomized trial
Design: The study was conducted as a double-blinded, randomized trial.
Despite numerous case series and reports of secondary gastrointestinal adenocarcinoma in carcinoid patients, in this retrospective case-controlled series, there appears to be no difference in rates of adenomatous polyps, advanced adenomas, or adenocarcinoma in small intestinal and colorectal carcinoid patients compared to a control population. These findings advocate the average risk of colorectal cancer in carcinoid patients.