Clinical trials and clinical studies that require registration

Clinical trials and clinical studies must be registered in public clinical trial registries. This page contains information about the definition of different study types and which ones require registration, as well as where the trials/studies can be registered depending on the study type.

Definitions of clinical trials and clinical studies

Clinical trial

A clinical trial, according to the EU-regulation No 536/2014, is defined as:

“Any study performed on humans to determine or confirm the clinical, pharmacological or pharmacodynamic effects of one or more investigational medicinal products, to identify adverse reactions to one or more investigational medicinal products or to study the absorption, distribution, metabolism and excretion of one or more investigational medicinal products, in order to ensure the safety or efficacy of those medicinal products”.

Trial drugs can be those that are under development or those that are already approved. The Medical Products Agency (Läkemedelsverket) provides a series of criteria to determine if the study is considered a clinical trial that must be registered and approved by Läkemedelsverket and to be registered in CTIS. Researchers can determine whether their clinical trial must be approved by Läkemedelsverket by assessing these requirements on Läkemedelsverkets webpage about definition and criteria.

Clinical study

A clinical study is defined by ICMJE and WHO as:

“Any research project that prospectively assigns people or a group of people to an intervention, with or without concurrent comparison or control groups, to study the relationship between a health-related intervention and a health outcome. Health-related interventions are those used to modify a biomedical or health-related outcome; examples include drugs, surgical procedures, devices, behavioral treatments, educational programs, dietary interventions, quality improvement interventions, and process-of-care changes.

Registration is required if a study meets one of these criteria for a clinical study. In cases where it is uncertain whether a study meets the definition of a clinical study, then researchers should verge on the side of registration, if the subsequent plan is to publish in an ICMJE journal. That is because many journals require that a clinical study is registered in a clinical trial registry before the first patient/participant is recruited, or as soon as possible afterwards, in order for a study to be published.

Transparency in clinical research at Karolinska Institutet

Transparency in clinical research implies the sharing and use of clinical trial data across global registries. Greater clinical trial transparency leads to improved patient and medical care, spurs scientific innovation, and produces overall better healthcare systems.

Karolinska Institutet is committed to making information about the clinical research conducted at KI both visible and accessible. In an effort to improve transparency in clinical research within open science, in 2020 the University Director issued an initiative to centralize the clinical trial registration and reporting process at KI.

Where can I register my study?

Clinical trials must be registered in Clinical Trials Information System (CTIS). CTIS is a web portal where everything regarding the clinical trial is managed in one system. This means that you will not apply for an ethics approval before you’re registering your trial, but one single clinical trial application is submitted to CTIS, where Läkemedelsverket and Swedish Ethical Review Authority (Etikprövningsmyndigheten) will have access to the application. The regulatory authorities will review the application and provide feedback and decisions to the applicant directly via the CTIS portal. Compliance & Data Office (CDO) is offering support for researchers when registering clinical trials in CTIS, see more information on our webpage about CTIS.

Clinical studies can be registered in different clinical trial registries, and it is recommended to register in a so-called WHO Primary registry or WHO Data provider. The most common clinical trial registry that is used by researchers at KI is CDO is offering support for researchers when registering clinical studies in, see more information on our webpage about

Please note that WHO recommends that clinical trials and clinical studies are only registered once and in only one clinical trial registry.

Clinical studies funded by the Swedish Research Council (Vetenskapsrådet)

The Swedish Research Council (Vetenskapsrådet) has new guidelines from 2022 stating that all clinical studies/trials funded by the Swedish Research Council must be registered in a public clinical trial registry. The study shall be registered before recruitment of patients/participants begins and also applies to studies that started before they were granted funding by the Swedish Research Council.

It is Karolinska Institutet’s responsibility to make sure the PI of the study is registering and updating the study. Affected researchers will therefore be contacted by Compliance & Data Office for information and guidance.

Read more on the Swedish Research Council’s webpage about requirements, terms and conditions.


Compliance & Data Office

Content reviewer: