Screening Prior to Clinical Trial Enrollment

Successful clinical trial participation depends on the screening process of potential participants. It is performed to determine whether a person meets the inclusion criteria for a particular study. These criteria tend to be quite strict, especially for Phase I and II clinical trials. This results from safety requirements for new treatments established by the FDA with the aim to minimize the potential risk of side events from the medicine.

Inclusion and Exclusion Criteria for a Clinical Trial

age (e.g. between 18 and 65 years old)
sex
health condition (clinical trials are often designed for specific diagnosis)
the intensity of symptom presentation
stage of the disease (early, acute, chronic)
current treatment (medications taken by a potential study participant)
place of residence of a potential participant (distance to clinic)
high BMI
comorbidities (e.g. diabetes, high blood pressure, migraine)
use of illicit drugs
pregnancy or breastfeeding

Clinical trial organizers can assess some of these criteria during pre-screening before the clinic visit.

Pre-Screening in Clinical Trials

Pre-screening involves a survey or questionnaire to determine if a potential participant meets the main inclusion criteria for participation in a trial.

In most cases, pre-screening testing can be performed over the phone, during a consultation with your doctor, or using an online questionnaire. But some inclusion criteria for the study require a more thorough assessment and a visit to the trial site. Therefore, potential participants are invited to participate in the next stage of the selection process, which involves screening in the clinic.

Screening in Clinical Trials

During the screening visit, potential participants meet with clinic staff, the clinical trial coordinator, and the principal investigator. They provide patients with all information about the study stated in informed consent. The number of tests and assessments will depend on the clinical trial protocol.

This stage of selection requires a detailed examination of the patient's medical history. Screening results provide valuable information about a potential patient's health condition that can ensure safe participation in a clinical trial.

The Screening Process

Introduction to the informed consent (contains full information about the upcoming clinical trial).
Signing an informed consent form with the primary investigator.
Doctor's examination, height, and weight measurement.
Laboratory analysis (clinical blood analysis, clinical urine analysis, biochemical blood analysis, HIV test, syphilis test, viral hepatitis B and C test).
Alcohol test.
Urine analysis for medicine and addictive substances abuse.
Pregnancy test (for female volunteers).
Instrumental methods of examination (ECG).
Based on the results of the screening, the primary investigator decides whether the volunteer is allowed to participate in a trial or not.

Informed Consent

Potential participants must read and sign the informed consent form before any laboratory/diagnostic tests are performed or any documents are completed.

Informed consent is a document required by the FDA that must be written in language easily understood by the participants. It includes all the information about a specific clinical trial before patients decide to join it. The informed consent specifies information about the investigational drug, the risks and benefits of its use, the differences between the new drug and patients’ current medications. Besides, the informed consent will clarify the trial process, description of the tests and procedures, and the schedule of clinic visits.

You should read the informed consent form carefully before signing it. Patients can ask to speak with a clinical trial coordinator to get more information. You can also take the informed consent home and discuss clinical trial participation with your doctor and family.