2. Synopsis
The synopsis of a clinical study report tells the whole study in brief, so that a reader can grasp its essential findings without opening the rest of the report. Section 2 of ICH E3 asks for a short summary that illustrates the results with numbers, and the questions and answers on E3 address how long it may run. The example synopsis in Annex I lists the fields it carries, from the study’s identity through its objectives, methods and participants to its efficacy and safety results and its conclusion. The CORE Reference manual moves that example into the body of the guideline and changes some of what its fields ask for.
What the synopsis is for
The synopsis tells the whole study story in miniature: why the study takes place, how it works, who participates, what the results show, and what they mean. A reader should understand the essential findings without opening the rest of the report.
A reader handed a report hundreds of pages long needs answers to a few connected questions before examining its detailed evidence, and the synopsis answers each of them:
| Everyday question | Information in the synopsis |
|---|---|
| What is this study, and who runs it? | Study identity, investigators, centres, and dates |
| What question does it ask? | Objectives |
| How does it seek an answer? | Participants, treatments, design, measurements, and analysis |
| What actually happens? | Participant flow and important departures from the plan |
| What does it find? | Numerical efficacy and safety results |
| What can be concluded? | An interpretation supported by those results |
A synopsis is a concise overview. In a clinical study report it serves scientific and regulatory readers. It is not a patient-facing plain-language summary, which differs in its intended audience and its level of technical detail.
What Section 2 asks for
Section 2 of E3 asks for a brief summary of the study, usually within three pages, and says that the synopsis should include numbers that illustrate the results, not only text or p-values.
The length of the synopsis is one of the main clarifications in the questions and answers ICH issued on E3. E3 sets three pages or less, while the ICH M4E guideline on the electronic common technical document allows up to ten pages. The longer allowance rests on synopses being stand-alone documents, which should be intelligible without reference to the rest of the report, and the synopsis should be written to be used as a stand-alone document within the common technical document.
How much of that length a synopsis needs depends on the study. Three pages are often far too short for complex and large studies, however concisely the synopsis is written, and complex or large and important studies may require a synopsis longer than E3's three pages. The ten pages are an example rather than an absolute limit, though a synopsis should not need to exceed them considerably. The questions and answers leave the three-page suggestion in place, so keeping a synopsis as short as possible still seems good advice, though a synopsis that needs more than three pages is no cause for worry. What matters is that the synopsis keeps its essential interpretation, not that every study fits an arbitrary page count.
What makes the synopsis work
The synopsis follows a small but complete argument: the objective determines the design, the design determines the measurements and analysis, and the observed findings support a bounded conclusion. Its product names, dates, participant numbers, methods and results agree with the full report, and a reader can understand its argument without following a reference into another section of the report.
The common technical document is the organised submission package through which the synopsis may reach a reviewer independently of the complete report, so the synopsis needs enough information to stand on its own. A table layout is optional, and references that require opening another section of the report should be avoided.
What the synopsis contains
Annex I, a supplementary part of E3, gives an example of a synopsis format used in Europe. Its fields show the information the summary needs to organise, and they serve as prompts rather than as a compulsory page template. An actual synopsis carries its essential information within itself.
Study identity and place in the submission
| Annex I field | What it means |
|---|---|
| Sponsor/company | Identifies the sponsor named on the title page. |
| Finished product | The medicine in its administered form, such as a tablet or injection. |
| Active ingredient | The substance intended to produce the medicine's pharmacological effect. A product's name and its active ingredient's name may differ. |
| Individual study table; dossier volume and page | Information that locates this summary within the larger submission. A dossier is the assembled body of documents submitted for review. The example uses volume and page numbers; the field's purpose is traceability. |
| For national authority use only | Space the example form reserves for the reviewing authority. It asks the writer for no additional scientific findings. |
| Title of study | The formal study title, matching the report's identifying information. |
| Investigators | Identifies the investigators responsible for the clinical work. |
| Study centres | The sites where study activities take place, such as hospitals or clinics. |
| Publication reference | A bibliographic reference to a publication reporting the study, if one exists. A CSR can exist without a corresponding journal article. |
| Studied period | The calendar period, with first enrolment and last completion dates. |
| Development phase | The study's place in clinical development, such as Phase II or Phase III. |
The example repeats the identifying fields on its continuation page, which helps the study keep its identity when a page is viewed separately. The repetition does not create another study or another set of results.
Objectives, participants and treatments
Objectives describe what the study seeks to learn, for example “Assess whether ABC-123 improves blood-pressure control over 12 weeks compared with placebo.” An objective is the question; the result comes later.
Methodology gives the essential study design, in the design terms the title page uses. It includes enough detail to make the comparison understandable.
Number of patients, planned and analysed distinguishes the intended sample from the data actually used. A study might plan 200 participants, assign 204, and have 202 receive treatment. Different analyses can include different groups, so the summary identifies the relevant denominators. A denominator is the total against which a count or percentage is interpreted, and it should remain clear whether “20%” means 20% of everyone assigned, everyone treated, or another defined group.
Diagnosis and main inclusion criteria describe the condition and the key rules that decide who can enter, for example “Adults with confirmed hypertension that remains uncontrolled despite specified background treatment.” These facts define the population to which the findings most directly apply. An exhaustive eligibility checklist belongs in the full report.
Test product, dose, mode of administration, and batch number identifies what participants receive, with the dose and the way of giving treatment stated explicitly. A batch number identifies a manufactured lot and supports traceability. A fictional entry is “ABC-123, 10 mg orally once daily; batch AB001.”
Duration of treatment is how long an individual receives therapy. It differs from the calendar study period: a trial can recruit over two years while each participant takes treatment for 12 weeks.
Reference therapy, dose, mode of administration, and batch number gives the same information for the comparator, an active treatment or placebo. The comparator determines what the study's treatment contrast means.
Evaluation criteria and statistical methods
Criteria for evaluation describe the measurements used to assess benefit and harm:
- Efficacy concerns whether treatment produces its intended beneficial effect under the study conditions, for example the measured change in a symptom score between the starting assessment and Week 12.
- Safety concerns unfavourable effects and other evidence about risk. Assessments may include reported medical problems, laboratory tests, and physical measurements.
A specified outcome used to evaluate the study question is an endpoint, and the main one is the primary endpoint. Its definition needs a measurement and a time point; “asthma improvement” alone is too vague.
Statistical methods explain how the study turns observations into comparisons. At synopsis level, the reader needs the principal analysis approach and critical assumptions, including the analysed population and the handling of unavailable measurements when relevant. The full mathematical machinery belongs in the detailed report. The method this field states needs to match the result the synopsis reports under it.
Participant flow, deviations and compliance
The synopsis explains how the study actually unfolds, which its plan does not establish: who starts or leaves the trial, important departures from its procedures, and how closely participants follow treatment. The questions and answers on E3 call for critical information about the study population, participant disposition, important protocol deviations and treatment compliance. The fuller accounts appear in the report's sections on participant disposition, protocol deviations and treatment compliance, but their key implications belong in the synopsis itself.
Extensive treatment discontinuation, for example, can limit the meaning of a favourable result. The synopsis needs enough context to make that limitation visible, even though the detailed accounting appears elsewhere in the report.
Results, conclusion and report date
Annex I separates efficacy results, safety results, and conclusion, which keeps both the observations and their interpretation visible.
A fictional efficacy statement might read:
At Week 12, mean systolic blood-pressure reduction is 12 mmHg in the investigational-treatment group and 7 mmHg with placebo. The estimated additional reduction is 5 mmHg, with a 95% confidence interval of 2 to 8 mmHg.
Systolic blood pressure is the pressure during the heartbeat’s contraction; mmHg means millimetres of mercury. A mean is an arithmetic average. The example gives the group findings, the comparison and its uncertainty.
A p-value does not tell the reader the size of the benefit, so “The treatment difference is statistically significant” cannot replace the numerical comparison E3 requests.
A fictional safety statement might read:
At least one adverse event occurs in 30 of 100 treated participants receiving ABC-123 and 20 of 100 receiving placebo. Treatment discontinuation because of an adverse event occurs in 5 and 2 participants, respectively.
An adverse event is an unfavourable medical occurrence; the term alone does not establish that the medicine causes it. The counts in the example describe affected participants, not the total number of episodes. The synopsis selects the important safety findings, including serious outcomes and other material concerns where relevant, without attempting to reproduce every table.
A useful conclusion connects the principal findings with their practical limits, for example “ABC-123 produces greater blood-pressure reduction than placebo over 12 weeks, with more adverse events and treatment discontinuations. The study provides limited information about longer-term use.” The wording must remain proportionate to the actual evidence, and a compact summary still needs to represent unfavourable findings and uncertainty.
Date of the report, the final Annex I field, identifies the report the synopsis represents. It differs from the study-completion date because analysis and reporting take place after data collection.
The synopsis in CORE Reference
The synopsis is part of the report's text rather than an appendix to it, so it is better placed in the body of the guideline than in E3's Annex I, and the CORE Reference manual places it there as an example synopsis.
Three changes concern what the EU Clinical Trials Regulation additionally requires for EU studies, and CORE Reference carries them as value-add comments that give guidance. They cover the summary of results for the clinical trial, with a suggestion to include the EU-relevant points so that the synopsis is easier to use for posting; the background and rationale for the study, in line with the regulation, with a further comment giving more detail; and the breakdowns by age group and gender, which the regulation also requires.
Two more concern the E3 fields themselves. CORE Reference clarifies that only the main inclusion and exclusion criteria should be presented, rather than the entire eligibility list copied from the protocol. It also suggests including the endpoints in the synopsis, clearly linked to the objectives they serve, and supplies example subheadings for them; with the endpoints there, E3's separate criteria-for-evaluation row is not needed, and CORE Reference omits it.
A further comment concerns the estimand. When CORE Reference was published, ICH E9 on estimands existed only as a concept paper, so the manual carries an awareness comment marking where eventual changes might affect the synopsis: estimands would need to be included with the study endpoints.