Get Your Research Published: Master STROBE Guidelines in 2024
Over 70% of medical research is observational, yet poor reporting leads to manuscript rejections. Don’t let inadequate reporting standards derail your publication goals.
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What is STROBE?
STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) is an international initiative that provides guidelines for reporting observational studies in epidemiology.
Why STROBE Guidelines Are Essential for Medical Research Publication
Over 70% of medical research is observational, yet inadequate reporting standards lead to manuscript rejections and reduced research impact. Poor reporting hampers peer review, systematic reviews, and evidence synthesis. The STROBE initiative addresses these critical deficiencies by providing standardized reporting guidelines that improve manuscript quality and publication success rates.
STROBE Study Designs: Cohort, Case-Control & Cross-Sectional Studies
Definition: Studies that follow participants over time to observe outcomes. Can be prospective (following participants forward in time) or retrospective (using historical data).
Key feature: Exposure status is determined before outcome occurrence
Definition: Studies that compare people with a condition (cases) to those without (controls) to identify risk factors or exposures that may have contributed to the outcome.
Key feature: Outcome status determines selection, then exposure history is assessed
Definition: Studies that examine exposure and outcome at the same point in time in a defined population, providing a “snapshot” of health status.
Key feature: Exposure and outcome measured simultaneously
Background and Development
The STROBE Initiative
The STROBE initiative was developed by an international group of epidemiologists, methodologists, statisticians, researchers, and journal editors. The development process involved:
- Systematic review of existing guidance
- Analysis of empirical evidence on reporting quality
- Expert consensus through multiple workshops
- Extensive consultation with the research community
- Pilot testing with journals and authors
The STROBE recommendations are based on empirical evidence about the quality of reporting in medical literature and theoretical considerations about what information readers need to assess the validity and applicability of study results.
Structure of STROBE
The STROBE Statement consists of:
- 22 checklist items covering all major sections of a research article
- 18 items common to all three study designs
- 4 items specific to each study design
- Detailed explanation and elaboration for each item
| Article Section | Item Numbers | Common Items | Design-Specific |
|---|---|---|---|
| Title and Abstract | 1-1b | 2 | 0 |
| Introduction | 2-3 | 2 | 0 |
| Methods | 4-12 | 6 | 3 |
| Results | 13-17 | 4 | 1 |
| Discussion | 18-21 | 4 | 0 |
| Other Information | 22 | 1 | 0 |
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The Complete 22-Item STROBE Checklist
Each item below includes the official STROBE guidance, rationale, and practical examples from published studies.
Title and Abstract
STROBE Requirement: Indicate the study’s design with a commonly used term in the title or the abstract
Readers should be able to easily identify the type of study being reported. The study design determines the appropriate methods for data collection, analysis, and interpretation of results.
Cohort study: “Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies”
Case-control study: “Mobile phone use and brain tumours in the CERENAT case-control study”
Cross-sectional study: “The global burden of disease: a comprehensive assessment of mortality and disability from diseases, injuries, and risk factors in 1990 and projected to 2020”
“Risk factors for coronary heart disease in women” (design not specified)
“Association between vitamin D and cancer” (could be any study design)
STROBE Requirement: Provide an informative and balanced summary of what was done and what was found
The abstract is often the only part of an article that is readily available to readers. It should provide enough information to understand the study’s purpose, methods, results, and conclusions without access to the full text.
Structured Abstract Components:
| Section | Content Requirements | Typical Length |
|---|---|---|
| Background/Objective | Study rationale, research question, specific objectives | 50-75 words |
| Methods | Study design, setting, participants, exposures, outcomes, statistical analysis | 75-100 words |
| Results | Numbers of participants, key findings with effect sizes and confidence intervals | 100-125 words |
| Conclusions | Key results interpretation, limitations, implications | 25-50 words |
Background: Previous studies have suggested an association between coffee consumption and reduced risk of type 2 diabetes, but the evidence has been inconsistent. We examined this association in a large prospective cohort study.
Methods: We followed 117,000 women in the Nurses’ Health Study (1980-2008) and 45,000 men in the Health Professionals Follow-up Study (1986-2008). Coffee consumption was assessed using validated food frequency questionnaires. We used Cox proportional hazards models to estimate hazard ratios (HR) and 95% confidence intervals (CI).
Results: During 2.5 million person-years of follow-up, 7,300 cases of type 2 diabetes were documented. Compared with non-coffee drinkers, the multivariable HR for type 2 diabetes was 0.92 (95% CI: 0.85-0.99) for 1 cup/day, 0.85 (0.79-0.91) for 2-3 cups/day, and 0.75 (0.69-0.82) for ≥4 cups/day (P for trend <0.001).
Conclusions: Higher coffee consumption was associated with lower risk of type 2 diabetes in a dose-response manner. These findings support the hypothesis that coffee consumption may help prevent type 2 diabetes.
Introduction
STROBE Requirement: Explain the scientific background and rationale for the investigation being reported
Readers need to understand why the study was undertaken. The background should place the study in context by describing current knowledge, identifying gaps or controversies, and explaining how the study addresses these issues.
Essential Elements of Background Section:
- Current state of knowledge: What is already known about the topic?
- Knowledge gaps: What important questions remain unanswered?
- Controversies: Are there conflicting findings in the literature?
- Study rationale: Why is this particular study needed?
- Study contribution: How will this study advance knowledge?
Current knowledge: “Epidemiological studies have consistently shown that physical activity reduces the risk of cardiovascular disease. Several meta-analyses have reported risk reductions of 20-30% for the most active compared to least active individuals.”
Knowledge gap: “However, most previous studies have relied on self-reported physical activity measures, which are subject to recall bias and misclassification. Few studies have used objective measures of physical activity to examine this association.”
Study rationale: “Objective measurement of physical activity using accelerometry provides more accurate assessment of activity patterns and may reveal different associations than those observed with self-reported measures.”
STROBE Requirement: State specific objectives, including any prespecified hypotheses
Clear objectives help readers understand exactly what the study aimed to accomplish. Prespecified hypotheses demonstrate that analyses were planned rather than exploratory, which affects interpretation of statistical significance.
Primary objective: To examine the association between objectively measured physical activity and risk of cardiovascular disease in postmenopausal women.
Secondary objectives: To assess whether this association varies by (1) age group (<65 vs ≥65 years), (2) body mass index (<25 vs ≥25 kg/m²), and (3) presence of diabetes at baseline.
Prespecified hypothesis: We hypothesized that higher levels of objectively measured physical activity would be associated with reduced cardiovascular disease risk, with stronger associations among older women and those with higher BMI.
Methods
STROBE Requirement: Present key elements of study design early in the paper
Early identification of study design helps readers understand the methods and interpret results appropriately. Different designs have different strengths, limitations, and analytical approaches.
Cohort study: “We conducted a prospective cohort study using data from the Women’s Health Initiative, which enrolled 161,808 postmenopausal women aged 50-79 years at 40 clinical centers across the United States between 1993-1998, with follow-up through 2020.”
Case-control study: “We conducted a population-based case-control study in Ontario, Canada. Cases were women aged 20-74 years with incident breast cancer diagnosed between 2006-2012, identified through the Ontario Cancer Registry. Controls were age-matched women without breast cancer, selected through random digit dialing.”
Cross-sectional study: “We analyzed data from the National Health and Nutrition Examination Survey (NHANES) 2015-2018, a nationally representative cross-sectional survey of the non-institutionalized US population.”
STROBE Requirement: Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data collection
Setting information helps readers assess the generalizability of findings to other populations and contexts. Temporal information is crucial for understanding potential confounding by secular trends and for replication attempts.
Essential Setting Information:
- Geographic location: Country, region, city, specific institutions
- Healthcare context: Primary care, specialty clinics, hospitals, community
- Population characteristics: Demographics, socioeconomic status, health system
- Time periods: Recruitment, exposure assessment, follow-up, data collection
- Environmental context: Relevant policies, interventions, or events during study period
“The study was conducted in the Lombardy region of northern Italy, which has a population of 10 million and a well-established healthcare system with universal coverage. We recruited participants from 15 primary care practices in Milan and surrounding suburbs between January 2010 and December 2012. Follow-up continued through December 2020. During the study period, Italy implemented several public health initiatives including smoking bans in public places (2005) and mandatory salt reduction in processed foods (2012).”
STROBE Requirement:
Give the eligibility criteria, and the sources and methods of selection of participants. Describe methods of follow-up
Give the eligibility criteria, and the sources and methods of case ascertainment and control selection. Give the rationale for the choice of cases and controls
Give the eligibility criteria, and the sources and methods of selection of participants
Detailed description of participant selection is essential for assessing potential selection bias and determining the generalizability of results. Different selection methods can lead to different types and degrees of bias.
Eligibility criteria: Women aged 50-79 years, postmenopausal (no menstrual periods for ≥12 months or bilateral oophorectomy), able to provide informed consent, and expected to reside in the area for ≥3 years.
Exclusion criteria: Previous breast cancer, current use of sex hormones, life expectancy <3 years due to serious illness.
Recruitment: Participants were recruited through mass mailings to age-eligible women identified from voter registration lists, supplemented by media campaigns and community outreach events. Response rate was 9.2% of those contacted.
Follow-up methods: Annual questionnaires mailed to participants, with telephone follow-up for non-responders. Medical records obtained for reported events and deaths. Vital status confirmed through National Death Index searches.
Complete Study Examples
Example 1: Cohort Study
Title and Abstract
Title: “Physical Activity in Midlife and Risk of Dementia: A 20-Year Prospective Cohort Study of 15,000 Adults”
Abstract:
Background: Physical activity may protect against cognitive decline and dementia, but long-term prospective evidence from midlife is limited.
Methods: We followed 15,000 adults aged 40-60 years from the Whitehall II cohort (1997-2017). Physical activity was assessed using validated questionnaires every 5 years. Dementia cases were identified through electronic health records, cognitive assessments, and death certificates. We used Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CI).
Results: During 285,000 person-years of follow-up (median 19 years), 1,235 participants developed dementia (incidence rate: 4.3 per 1,000 person-years). Compared to inactive participants (<1 hour/week), those with moderate activity (2.5-7 hours/week) had an HR of 0.72 (95% CI: 0.63-0.83) and those with high activity (>7 hours/week) had an HR of 0.65 (95% CI: 0.55-0.78) after adjusting for age, sex, education, cardiovascular risk factors, and APOE genotype.
Conclusions: Regular physical activity in midlife was associated with substantially reduced dementia risk in this large prospective cohort, with a dose-response relationship.
Example 2: Case-Control Study
Study Design and Participants
Design: Population-based case-control study conducted in 13 countries as part of the INTERPHONE study.
Cases: Adults aged 30-59 years with histologically confirmed glioma or meningioma diagnosed between 2000-2004, identified through cancer registries and hospital records. Response rate: 78% for glioma cases, 85% for meningioma cases.
Controls: Population controls matched by age, sex, and region, selected through random digit dialing or population registries. Response rate: 53%.
Exposure assessment: Detailed interviews about mobile phone use history, including start date, frequency, duration of calls, and phone models used. Phone records obtained for subset of participants to validate self-reported use.
Flow Diagrams and Visual Reporting
Flow diagrams are essential for transparent reporting of participant selection and follow-up in observational studies.
Cohort Study Flow Diagram
Example: Prospective Cohort Study Flow
Potentially eligible participants identified
from population registry
n = 125,000
↓
Invited to participate
n = 50,000
Excluded (n = 75,000)
• Age <50 or >75 years: 45,000
↓ • Previous cancer: 15,000
• Unable to contact: 15,000
Agreed to participate
n = 18,500 Declined participation (n = 31,500)
• No reason given: 20,000
↓ • Too busy: 8,000
• Privacy concerns: 3,500
Completed baseline assessment
n = 17,800 Excluded at baseline (n = 700)
• Incomplete data: 400
↓ • Withdrew consent: 300
Followed for outcomes
n = 17,800
↓
Completed follow-up
n = 16,200 Lost to follow-up (n = 1,600)
• Moved away: 800
↓ • Withdrew: 400
• Died (non-outcome): 400
Available for analysis
n = 16,200
Case-Control Study Flow Diagram
Example: Case-Control Study Flow
CASES CONTROLS
Potential cases identified Potential controls identified
from cancer registry from population registry
n = 2,500 n = 15,000
↓ ↓
Eligible cases Eligible controls
n = 2,100 n = 12,000
Excluded (n = 400) Excluded (n = 3,000)
• Age <30 or >70: 200 • Age not matched: 1,500
• Previous cancer: 100 • Previous cancer: 800
• Unable to contact: 100 • Unable to contact: 700
↓ ↓
Invited to participate Invited to participate
n = 2,100 n = 8,400 (4:1 ratio)
↓ ↓
Agreed to participate Agreed to participate
n = 1,650 n = 4,200
Declined (n = 450) Declined (n = 4,200)
• No reason: 250 • No reason: 2,800
• Too ill: 150 • Too busy: 1,000
• Privacy: 50 • Privacy: 400
↓ ↓
Completed interview Completed interview
n = 1,620 n = 4,050
Excluded (n = 30) Excluded (n = 150)
• Incomplete data: 30 • Incomplete data: 150
↓ ↓
FINAL ANALYSIS SAMPLE
Cases: n = 1,620 Controls: n = 4,050
- Include all stages of participant selection
- Provide specific numbers and reasons for exclusions
- Show response rates at each stage
- Use clear, standardized terminology
- Consider using software tools for consistency
Tools and Resources
- Many journals require STROBE checklist submission
- Some journals have modified STROBE requirements
- Check specific journal guidelines before submission
- Consider journal’s target audience and scope
- CONSORT: Randomized controlled trials
- PRISMA: Systematic reviews and meta-analyses
- STARD: Diagnostic accuracy studies
- CARE: Case reports
- Flow diagram software (e.g., Lucidchart, Draw.io)
- Reference management tools
- Statistical software documentation
- Manuscript preparation software
von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP; STROBE Initiative. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. PLoS Med. 2007;4(10):e296.