How to read a ClinicalTrials.gov record

What the registry is

ClinicalTrials.gov is a registry and results database maintained by the US National Library of Medicine. It includes studies from many countries, including studies conducted in Canada. A record is a structured summary supplied by the study sponsor or investigator, not a personal recommendation or a complete account of the scientific evidence.

The site explains the parts of a record and related terms. A registry listing does not certify that a treatment is safe or effective, and registration is not an endorsement by a government. Records may be incomplete, technical, or updated at a later date. Use the information to frame questions for a clinician or research team, not to make a medical decision by itself.

Identify the research question

Begin with the title, brief summary, study type, and condition or topic. Titles can be technical or abbreviated, so read the summary to understand the question being investigated. Confirm that the intervention and population match what you are looking for. Search result snippets may omit important context.

An interventional study assigns or evaluates an intervention. An observational study follows participants without assigning the intervention under study. This distinction does not itself tell you whether a study is rigorous or relevant. Read the detailed description, because the study design determines what conclusions the researchers can draw.

Status, dates, and locations

Recruitment status may be listed as recruiting, active but not recruiting, completed, terminated, or another category. Status can change, and a listing may not immediately reflect a local site’s current capacity. A recruiting status does not mean every location is open or that a particular person meets the requirements. Dates may be estimated or actual, so distinguish planned milestones from completed ones.

Review the locations and contact information. A person in Canada can verify whether a Canadian site is participating and ask the listed research team whether enrolment is currently open. Avoid sending sensitive health or identity information through an unverified channel. Study staff, not the public listing, assess eligibility under the research protocol.

Eligibility and design

Eligibility criteria explain who may or may not participate. They can include age, diagnosis, previous treatment, test results, other conditions, or location. The criteria apply to that particular study, not as a general definition of a disease. Researchers may update criteria as the study proceeds. Only the research team can determine eligibility after reviewing the relevant information.

Design fields may describe allocation, masking, assignment, and groups. Randomization means assignment by chance. Masking means some participants or researchers may not know which intervention is assigned. A comparator could be usual care, another intervention, placebo, or no intervention. These terms provide context, but should not be interpreted without the complete study description.

Outcomes and posted results

An outcome measure is what researchers plan to measure and when. The primary outcome is a main measure for the research question. Secondary outcomes are additional measures. The name of an outcome, how it is measured, and the time point all matter. A planned measure is not a finding and does not show that a treatment has benefit.

When results are posted, review participant numbers, measured outcomes, time points, comparison groups, and the reported findings. Registry results are often structured summaries, not a peer-reviewed paper. Consider what limitations are described and whether the outcome matters to participants. A result in one study is not proof that an intervention will work for every person. Interpret it alongside other reliable evidence and clinical expertise.

Questions to ask

A record can help prepare questions for the research team: What would participation involve? What are the foreseeable burdens and risks? What alternatives exist? How are privacy and travel handled? Are there costs? Who can answer questions during the study? Consent materials and explanations should come directly from the research team. Participation is voluntary.

For questions about how research relates to personal health, consult a health professional who understands the situation. A study record is not an individualized assessment and cannot determine whether participation is appropriate.

Frequently asked questions

Sources

• ClinicalTrials.gov: How to Read a Study Record(opens in a new tab)
• ClinicalTrials.gov: Learn About Studies(opens in a new tab)
• ClinicalTrials.gov Glossary(opens in a new tab)
• Canada.ca: Clinical trials(opens in a new tab)

Written by the Chronic Pain Canada editorial team from the sources listed. Last updated October 2026.