Study Registration Platforms

ClinicalTrials.gov 

This is a widely recognised registry primarily designed for Randomised Controlled Trials (RCTs). However, it can also accommodate observational studies, though the process might be cumbersome. It is operated by the National Institutes of Health's National Library of Medicine. Registration on ClinicalTrials.gov is recommended before enrolling the first patient for trials, with no exceptions. It allows for the storage of study protocols and analysis plans for all study types. This platform helps prevent selective analysis and reporting of endpoints.

HMA-EMA Catalogues of real-world data sources and studies

Hosted by the European Medicines Agency this register focuses on non-interventional post-authorisation studies, both prospective and retrospective. Registration of relevant studies should be undertaken in compliance with legislation. 

The Open Science Framework (OSF)

This platform provides pre-registration services for observational studies and is encouraged to publish study protocols and analysis plans.

International Clinical Trials Registration Platform / World Health Organisation (ICTRP/WHO)

This is a global platform for clinical trial registration.

ISRCTN registry (International Standard Randomised Controlled Trial Number)

This registry actively promotes the use of Core Outcome Sets (COS) and engagement with the COMET database.

PROSPERO portal 

This is registry specifically for systematic reviews and meta-analyses.