What is an Open Label Study in Clinical Research?

Perhaps you are considering enrolling in a clinical trial, or are already enrolled, and the trial is described as an “open label study”. In this article, we will clarify what this term means and what it implies for you as a participant. For some additional perspective and to help you understand why the study is designed in this way, we also explain how these studies differ from other types of clinical trials.

Open label study definition

In an open label study, or open label trial, all participants know exactly what study drug (or ‘intervention’) they will be receiving in the study. Study physicians and investigators also know what each participant is receiving. That means that there is no uncertainty regarding whether or not you may be receiving a placebo rather than the study treatment. If there are two drugs under study (for example the novel study drug and the ‘standard treatment’), you will know exactly which one you are receiving.

Open label study vs. double blind study

We begin here with some background information. In clinical trials, it is common for participants to be divided into cohorts (study groups), with each receiving a different treatment. Researchers compare the health outcomes between participants who received the different interventions, allowing them to make conclusions about the efficacy and safety of the novel study drug, typically in relation to either no treatment (placebo) or the standard treatment. (More information about how studies are designed).

Participants are divided into groups randomly, in order to minimize any potential bias or unfairness that could be introduced by manually assigning subjects to groups. This process of random assignment is known as randomization, and can be performed using various different methods.

Clinical studies may also involve something called blinding. Blinding means that either the participants or the researchers (or both) are “blinded” - they are intentionally kept unaware of which group they have been assigned to, and thus they do not know which treatment they are receiving. Blinding of participants is done to prevent bias that could arise from participants changing their behavior in some way due to knowing which treatment they’re receiving. For example, if a trial were testing a new vaccine against the flu, participants who knew they were receiving a placebo instead of the vaccine may take extra precautionary measures to avoid catching the flu. This would introduce a type of bias in the results, since these behavioral differences add a confounding factor that makes the groups less similar, on average, and thus more difficult to compare.

In a double-blind study, neither the participants nor the researchers know what treatment any of the participants is receiving. Blinding of the researchers/investigators may be done to prevent them from accidentally sharing this information with participants or from making specific clinical decisions based on their knowledge of the treatment that patient is receiving, both of which could influence the results of the study. Studies can even be triple-blinded, wherein even the data analysis is done without knowing the grouping of participants.

Participants may, in some studies, be unblinded after the study is completed - in that case, you would be told which study group you were enrolled in after the study finishes. Note that this is not mandatory, however, and sometimes the blinding is maintained indefinitely.

In an open label study, there is no blinding involved. We define open label studies specifically by the absence of blinding. All of the participants and the investigators know what intervention each participant is receiving. If the study involves more than one group, participants will be aware of which group they are in, and will know if they are receiving the study drug, the standard treatment, or placebo or no treatment. Some open label studies don’t involve grouping at all - so-called single-arm trials - in those studies, all participants receive the same intervention, and they are all aware of what they are receiving.

Single blind study vs double blind study

As discussed above, in a double blind experiment, neither the participants nor the researchers know what treatment each participant is receiving. In a single blind study, only the participants are blinded to this information – the researchers still know what each participant is receiving.

Open label trial: Advantages for participants

For participants enrolled in an open label study or open label clinical trial, there are potential advantages of knowing exactly what treatment you are receiving. To begin, it removes one of the most common uncertainties people express regarding participating in clinical research studies - that of being randomized and not knowing what you will receive, with the possibility of receiving a placebo rather than the study treatment. Although open label studies may still involve the use of placebo, you will be aware if you are grouped to the placebo arm. For participants with a certain condition who are motivated to participate by the potential of finding relief from their condition, knowing what you are receiving may help you feel more comfortable.

Conclusions

We hope that this article has clarified some of the terminology used in clinical research, and that it helps you understand the different types of trials and what they may imply for you if you decide to participate. Remember that regardless of your grouping or blinding, participating in clinical research represents a significant contribution to the advancement of medical research and the development of new treatments for people with your condition, both now and in the future. With that said, participation is completely voluntary - the decision to participate is yours and yours alone (although it’s always a good idea to consult with your doctor and family members). Further still, you have the fundamental right to leave the study at any time, without needing to provide any explanation. However, it’s always best to speak openly with your site/investigator about any doubts that arise and see if you can resolve them, since your contribution is the most valuable if you remain in the study through to completion.