A Clinical Study Protocol (CSP), sometimes also referred to as Clinical Trial Protocol or simply as Protocol, is an overview of how the study will be executed, it contains a description of the study objective(s), design, methodology, statistical considerations, and organization of the study. Background information and the rationale for the study can be provided within the CSP or, if preferred, in other referenced documents. The purpose is to provide a roadmap for a diverse/broad audience that adequately addresses the key elements of the study. It is also used as source material for several other documents including, but not limited to, the Informed Consent Form, Statistical Analysis Plan, and Clinical Study Report.

Note: The terms ‘clinical trial’ and ‘clinical study’ are synonymous according to ICH E6; however, according to other sources, it is important to distinguish between clinical trial and clinical study. Per Regulation (EU) 536/2014, a clinical trial is a category within the broader group of clinical studies and involves an ‘intervention’ (eg, administration of a study drug).

The CSP is not systematically updated but can be amended before or during the study to change (add, remove, …) and/or clarify procedures and information. It is important to be clear, consistent, and ‘realistic’ to try to reduce or avoid protocol amendments (or protocol deviations).

The CSP is a multidisciplinary document involving a wide range of functions that provide input for several sections of the CSP. It can be quite simple and be written quickly with only a few drafts, which may be the case for Phase 1 or simple Phase 2 studies. The more complex CSP (for instance, in case of complicated Phase 2 or Phase 3 studies) can take months of discussion with multiple drafts. Patient input into the design is very valuable as they can identify potential issues regarding procedures or other aspects of the study. Their involvement may improve recruitment and retention status.

The Medical Writer can be involved in the document development process (eg, write with team input, circulate for review, implement review comments, facilitate meetings, ensure consistency) and can indicate issues or make useful suggestions.