Comparing One-Stage Versus Two-Stage Informed Consent for Clinical Trials

This research project is in progress. PCORI will post the research findings on this page within 90 days after the results are final. In the meantime, results have been published in peer-reviewed journals, as listed below.

One of PCORI’s goals is to improve the methods that researchers use for patient-centered outcomes research. PCORI funds methods projects like this one to better understand and advance the use of research methods that improve the strength and quality of comparative effectiveness research.

What is the project about?

Clinical trials test treatments to find out if they are safe and effective for patients. Before patients take part in a trial, researchers ask patients for informed consent. During the informed consent process, a doctor or researcher explains the purpose of the trial, answers the patient’s questions, and asks if the patient wants to take part. But this process can be confusing. For example, some patients may not understand that being assigned to a treatment by chance means they might not get the treatment being studied. Also, informed consent often occurs shortly after diagnosis, when patients may feel overwhelmed.  

Two-stage informed consent can help reduce patient stress by splitting up the consent process. In the first stage, researchers ask patients if they will agree to be part of a pool of patients from which the researchers select some patients by chance to hear about a new treatment. Researchers then assign patients by chance to hear about the new treatment or receive usual medical care. In the second stage, researchers give information about the new treatment only to patients assigned to the new treatment.

In this study, the research team is comparing standard one-stage consent to two-stage consent to see how well each improves patients’ stress and understanding of the benefits and harms of treatment.

How can this project help improve research methods?

Results may help researchers when considering ways to obtain informed consent for clinical trials.

What is the research team doing?

This study includes patients at a cancer center who were previously asked to take part in a research study but who have not yet completed informed consent. The research team is assigning these patients by chance to receive either one- or two-stage informed consent. Shortly after the informed consent process, the team is contacting patients to ask about their experience with the process. The team is asking patients if they felt anxiety or stress and if they had difficulty deciding whether to take part in the trial. Also, the team is giving patients a survey to see how well they understand the trial.

The research team is comparing patients’ stress, understanding about the trial, and willingness to take part in the trial between those who receive one-stage consent and those who receive two-stage consent. The team also is looking to see how well one- versus two-stage informed consent works for different types of trials, such as trials with high stakes (such as a trial to study chemotherapy to improve survival) versus those with low stakes (such as a study of relaxation techniques to improve pain during biopsy).

Research methods at a glance