Clinical Trial Protocols and Clinical Study Reports (CSRs): A Beginner’s Perspective
By Femi Fajimi | 28 April 2025
As I continue developing my skills in regulatory medical writing, I am learning how essential two key documents are to the clinical trial lifecycle: the protocol and the clinical study report (CSR).
Protocols define a study’s blueprint, while CSRs document its final results. As a beginner regulatory writer, understanding these documents, even at a simple level, is essential to appreciate how clinical trials are designed, monitored, and submitted to regulatory authorities.
In this post, I explain what each document involves, how they connect, and what beginners like me should focus on when learning to work with them.
What is a Clinical Trial Protocol?
A Clinical Trial Protocol is a detailed plan that describes:
- Why a study is being conducted
- How the study will be carried out
- Who can take part
- What will be measured
- How data will be analysed
Protocols are critical because they ensure that the study is scientifically valid, ethically acceptable, and regulatory compliant.
Protocols is written according to standards such as ICH E6 (R2): Good Clinical Practice.
Key Sections in a Simple Clinical Trial Protocol:
Even in a simple study (such as a single-site or early-phase trial), a protocol typically includes:
Title Page
Sponsor name, protocol title, protocol number, version, and date.
Background and Rationale
Explains the medical need and why the investigational product is being studied.
Objectives and Endpoints
Defines the primary and secondary aims of the study (e.g., measure symptom improvement) and how success will be measured.
Study Design
Describe the study type (e.g., randomised, open-label), duration, treatments, and randomisation method if applicable.
Eligibility Criteria
Lists who can or cannot participate (inclusion/exclusion criteria).
Study Treatments
Details the investigational product, dosing schedules, and administration.
Assessments and Procedures
Specifies clinical evaluations, laboratory tests, and visit schedules.
Safety Monitoring
Describes how adverse events will be detected, recorded, and reported.
Statistical Analysis Plan
Explains how data will be analysed to meet study objectives.
Ethics and Regulatory Compliance
Confirms that the study will follow ethical guidelines, with informed consent and ethics approval.
What is a Clinical Study Report (CSR)?
After the trial is complete, the Clinical Study Report (CSR) documents all key information about the study:
- How it was conducted
- What was found
- What conclusions were drawn
CSRs are written according to ICH E3: Structure and Content of Clinical Study Reports and form a core part of the submission package for regulatory approval.
A good CSR is:
- Clear and objective
- Comprehensive but concise
- Structured to allow easy regulatory review
Key Sections in a CSR:
Title Page and Synopsis
Summary of objectives, methods, and main findings.
Introduction
Background and purpose of the study.
Study Methods
Details about study design, randomisation, treatments, and study conduct.
Patient Disposition and Protocol Deviations
Number of participants enrolled, completed, withdrew, and why.
Demographics and Baseline Characteristics
Summary of participant profiles at baseline.
Efficacy Results
Detailed outcomes relating to the study’s objectives.
Safety Results
Adverse events, laboratory test changes, vital signs monitoring.
Discussion and Conclusions
Interpretation of results, limitations, and implications.
Appendices
Patient narratives (for serious adverse events), protocol amendments, and statistical tables.
🔗 How Protocols and CSRs Connect
During the planning stage of a clinical trial, the protocol defines how the study should be conducted, outlining the objectives, design, eligibility criteria, treatments, assessments, and regulatory compliance.
After the study is completed, the Clinical Study Report (CSR) is created during the execution and completion stage. The CSR describes what actually happened during the trial, summarises the data collected, analyses the outcomes, and draws conclusions based on the results.
Together, the protocol and CSR represent the full lifecycle of a clinical trial, from planning to reporting findings.
Sample protocol and CSR
Disclaimer:
The protocol and related documents were created for educational and demonstration purposes only. MolendiiP Pharma Ltd, Dermalexiin, and the study described are fictional.
Beginner Insights: What I Am Learning
As a beginner regulatory writer:
- A simple protocol teaches me how to think logically about trial planning.
- CSR teaches me how to organise and report complex clinical data clearly.
- Both documents require factual, neutral, and precise writing and promotional language must be avoided (ABPI Code compliance).
Protocols focus on hypotheses and plans.
CSRs focus on results and evidence.
Both require close attention to detail, version control, and alignment with international regulatory guidelines.
Final Thoughts
Learning about clinical trial protocols and clinical study reports has helped me better understand the clinical research process from start to finish.
As I grow as a regulatory medical writer, I recognise that these two documents form the essential “bookends” of every clinical trial: the beginning and the end.
Knowing how to read, write, and review simple protocols and CSRs is foundational for a career in clinical research writing, and I am excited to continue developing these skills.
References:
- International Council for Harmonisation (ICH). E6(R2) Guideline for Good Clinical Practice. 2016. Available at: https://ichgcp.net
- International Council for Harmonisation (ICH). E3 Guideline: Structure and Content of Clinical Study Reports. 1995.
- European Medicines Agency (EMA). Guidelines for Good Clinical Practice. 2021.
'Femi Fajimi 
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