Cochrane Central Register of Controlled Trials

The Cochrane Central Register of Controlled Trials (CENTRAL) is part of the Cochrane Library and is designed to support comprehensive searching for randomised and quasi-randomised controlled trials across health conditions, populations and interventions. It is widely recommended in guidance on systematic review methods as a core source of trial reports and trial registry records.

It is a valuable resource during protocol development because it enables investigators to understand the existing evidence and learn from previous trials. 
Using CENTRAL during protocol development can help investigators:

• Avoid unnecessary duplication of existing trials
• Identify evidence gaps that justify a new clinical study
• Learn from previous trial designs, including successful and unsuccessful methodological approaches
• Select clinically relevant outcomes that facilitate comparison with prior research
• Improve the quality of the protocol by incorporating lessons from earlier studies
• Support systematic literature reviews, which are increasingly expected by ethics committees, funders, and regulatory agencies when justifying a new trial.