When is a Trial Registered in Clinicaltrials.gov?

Colin G. Miller

Most people new to Clinicaltrials.gov (CT.g) do not appreciate that CT.g staff undertake a review cycle to ensure that each posting is correct and fulfills the requirements of the website. They have a mistaken expectation that as soon as they hit the Submit button, the site spits out their National Clinical Trial (NCT) number. But in reality, the NCT number appears only when the study is finally accepted for registration on CT.g.

This delay has to be factored into the process application timeline. Also the questions that may come back may require additional work on the part of the trial sponsor. Then once the changes have been made, the registration application has to go back into the review cycle. The team at CT.g are diligent and must have a highly variable workload. Depending on the number of studies being submitted at any one time, their response time will vary, as detailed on the CT.g web site.

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One other factor this creates is a false date of registration. The date of registration is the date the study is first submitted and not the final date when the study goes live on the website. It is difficult to assess this overhang and its affect on the gross study numbers at any one time. The delays come about in a number of ways:

  1. The study sponsor does not have the correct information issued in the first place.

  2. The sponsor has not completed the application correctly, which happens more often with those new to the system.

  3. The sponsor has to wait for the CT.g team to review the application.

  4. The sponsor needs more turn-around time to answer the questions correctly.

  5. The CT.g team needs a re-review to ensure everything is copacetic.


As of April 2019, the number of trials being registered on CT.g continues to increase.  Our partners at BrackenData monitor the data and at the end of the year we would like to put out the total number of new trials is ”XXX”, but we have found it takes up to  months to obtain the final number, suggesting that registration can be a long drawn-out process in many instances.

Notice that though clinical trial registration rates are trending up year over year, there is a drop in the database for the year 2018 because not all registration data from the previous year is reflected yet (at time of writing, September 2019).

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