STOPping Anticoagulation for Isolated or Incidental Subsegmental Pulmonary Embolism

  • End date
    May 8, 2024
  • participants needed
  • sponsor
    University of Birmingham
Updated on 8 October 2021


Pulmonary embolisms (PE) occur when blood clots cause a blockage of the blood supply to the lungs. A small PE located in the subsegmental pulmonary vasculature is identified as a subsegmental PE (SSPE). Anticoagulants are used to treat SSPE and work by preventing new clots from forming whilst the body's own mechanisms break down the clots, however they can also increase the risk of major and potentially life threatening bleeding. More recent observational data of routine care for SSPE showed very high complication rates of anticoagulation but in patients where treatment was withheld, this proved to be a safe strategy in terms of recurrent venous thromboembolism (VTE).

Computed tomography pulmonary angiography (CTPA) scans are now able to detect SSPE, however there are concerns that there is an over-diagnosis due to the incorrect interpretation of small artefacts. 1466 patients from approximately 50 sites will be recruited, these sites will consist of hospitals across the United Kingdom (UK). Patients 18 and over with isolated SSPE, confirmed by either CTPA or CT thorax with IV contrast, will be eligible for the trial. Patients will be randomised to either receive standard anticoagulation for at least 3 months (control) or no anticoagulation for at least 3 months (intervention). The participant will receive telephone follow up calls at 4, 12 and 24 weeks following the end of their treatment, and additional data will also be taken from their medical records at these time points. The participant isn't required to be contacted for the 52 week follow up as the data will be extracted from the National Health Service (NHS) Digital collection of Hospital Episode Statistics (HES). In total participation in the study will last 12 months. In addition the cost-effectiveness of no treatment versus treatment with full anticoagulation will be looked at and also improving on radiological diagnosis of SSPE.

Condition Subsegmental Pulmonary Embolism Nos
Treatment Warfarin, low molecular weight heparin, No Treatment, Direct Oral Anticoagulants
Clinical Study IdentifierNCT04727437
SponsorUniversity of Birmingham
Last Modified on8 October 2021


Yes No Not Sure

Inclusion Criteria

Age 18 years
SSPE diagnosed by the radiologist at the trial site by CTPA or CT thorax with IV contrast
No evidence of proximal deep vein thrombosis on doppler ultrasonography or CT / Magnetic Resonance venography
Heart rate (<110bpm)
Systolic blood pressure (100 mmHg)
Oxygen saturation (90%)
Written signed informed consent to the trial

Exclusion Criteria

Indication for hospital admission
>7 days empirical anticoagulation treatment immediately prior to randomisation
<28 days since first symptoms of proven or clinically suspected Coronavirus disease (COVID-19)
Known stage 5 chronic kidney disease
Patients with active cancer defined as cancer diagnosed within the past 6 months, cancer for which anticancer treatment was being given at the time of enrolment or during 6 months before randomisation, or recurrent locally advanced or metastatic cancer
Patients with previous unprovoked PE, thrombophilia or requiring long term anticoagulation for another reason
Patients with a Deep Vein Thrombosis / thrombus of an unusual site (e.g. upper limbs, associated with a line) that requires anticoagulation
Patients with active bleeding
Any condition which, in the opinion of the investigator, makes the participant unsuitable for trial entry due to prognosis/terminal illness with a projected survival of less than 3 months
Pregnancy confirmed by positive pregnancy test or post-partum period or actively trying to conceive
Inability to comply with the trial schedule and follow-up
Participation in a Clinical Trial of Investigative Medicinal Product (CTIMP) study
Clear my responses

How to participate?

Step 1 Connect with a study center
What happens next?
  • You can expect the study team to contact you via email or phone in the next few days.
  • Sign up as volunteer to help accelerate the development of new treatments and to get notified about similar trials.

You are contacting

Investigator Avatar

Primary Contact



Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

Learn more

If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

Learn more

Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

Learn more

Similar trials to consider


Not finding what you're looking for?

Every year hundreds of thousands of volunteers step forward to participate in research. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.

Sign up as volunteer

user name

Added by • 



Reply by • Private

Lorem ipsum dolor sit amet consectetur, adipisicing elit. Ipsa vel nobis alias. Quae eveniet velit voluptate quo doloribus maxime et dicta in sequi, corporis quod. Ea, dolor eius? Dolore, vel!

  The passcode will expire in None.

No annotations made yet

Add a private note
  • abc Select a piece of text from the left.
  • Add notes visible only to you.
  • Send it to people through a passcode protected link.
Add a private note