STROBE stands for Strengthening the Reporting of Observational Studies in Epidemiology and is a reporting standard for observational studies. The STROBE Initiative developed a checklist for articles on cohort, case-control, and cross-sectional studies. It specifies what information should be included in the published report regarding study design, data basis, analysis, and results.
Which Observational Studies STROBE Applies To
STROBE is aimed at analytical observational studies, i.e., works that investigate associations between exposures and health outcomes. Cohort studies follow groups over time, case-control studies compare individuals with and without an event, and cross-sectional studies capture characteristics at a specific point in time. There are common requirements for all three formats, while individual points are designed to be study-specific.
The statement published in 2007 comprises 22 checklist items. It covers the title and abstract, introduction, methods, results, discussion, and funding information. A separate document, “Explanation and Elaboration,” explains the background of the items and illustrates them with publication examples.
What Information the Checklist Makes Visible
A STROBE article identifies its study design early and describes the study population as well as the location and period of data collection. It explains how exposures, endpoints, potential confounders, and other variables were defined or measured. For missing values, study size, and statistical procedures, the information required to make the evaluation of observational data understandable must be provided.
The results should present participant numbers across study phases, descriptive data, outcome data, and main estimates. For cohort, case-control, and cross-sectional studies, the same general question can lead to different specifications, for example, because follow-up time or selection of controls are only relevant in certain designs. This differentiation prevents an observational report from imitating inappropriate schematic specifications.
Distinction: Reporting vs. Study Planning
The authors of the STROBE Statement explicitly clarify that their recommendations are not guidelines for the design or conduct of studies. STROBE therefore does not decide whether a registry, a cohort, or a case-control study provides the correct answer to a research question. Similarly, the checklist does not determine which confounders must be considered professionally.
An observational study or non-interventional study refers to the research project itself; STROBE refers to the standard for its article. STROBE differs from CONSORT by the absence of randomized allocation as a prerequisite. The two standards must not be mixed, as their participant flows, sources of bias, and analysis questions reflect different study logics.
The guideline also includes funding as a separate reporting item. This is relevant for observational studies because data access, selection of the research question, and evaluation can be organized differently among research groups, registries, and sponsors. STROBE does not require these constellations to preclude a specific conclusion; however, the article should present them in such a way that readers understand the origin of the data and the context in which the analysis was developed.
The standardization of the report structure does not promote spurious accuracy. Especially with retrospectively collected data, an article must explain what information was available and what was not. STROBE does not offer a formula for correcting biases. However, the report should clearly indicate whether, for example, exposures were recorded chronologically before an event and on what assumptions the interpretation is based.
When describing a cohort, for instance, it is crucial when follow-up began and ended; for case-control studies, however, how cases and controls were defined and selected. Cross-sectional studies, in turn, require clear information on the data collection situation and the population studied. These differences belong not only in a table footnote but also in the methods and results presentation. This is precisely why the STROBE checklist contains both common and design-dependent formulations.
Relevance for clinical trials
Observational data are frequently evaluated for drug safety, healthcare provision, or the investigation of rare events. In such analyses, data sources, time windows, selection criteria, and confounding influence the statement more strongly than a mere description of the endpoint would suggest. STROBE directs the report to precisely these crucial characteristics, allowing readers to assess the generalizability and limitations of a non-randomized evaluation.
Full-service CROs like Mediconomics support STROBE reports through a coordinated concept for study protocol, data collection plan, variable definitions, and statistical analysis plan. Epidemiology and biostatistics can review confounder strategies, handling of missing data, and design-appropriate outcome measures, while Medical Writing translates information from data sources and tables into the STROBE structure. In the monitoring of a non-interventional study, the distinction between observation and protocol-driven intervention remains central.
Frequently Asked Questions (FAQ)
Is STROBE a checklist for randomized clinical trials?
No. Randomized studies are reported using CONSORT. STROBE is designed for cohort, case-control, and cross-sectional studies.
Does STROBE also apply to registry data?
If an observational study with one of the covered designs is reported using registry data, STROBE may be applicable. The data source does not replace the description of the study design.
Does STROBE assess the quality of a study?
STROBE is primarily a standard for complete reporting. A checklist can identify missing information but does not replace a methodical quality assessment.
Regulatory References
- STROBE Statement — Checklist for Reporting Observational Studies.
- STROBE Explanation and Elaboration — Explains the 22 items with methodological background.
- ICH E6(R3) Good Clinical Practice — Regulates GCP principles for clinical trials, not STROBE as a publication format.
- ICMJE Recommendations — Refer to STROBE for observational studies.