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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

Compression stockings might be unnecessary for patients at moderate or high risk of blood clots who are undergoing planned surgery.

A study called GAPS suggests that anti-clotting medicine alone is just as effective as using it in combination with compression stockings. 

Researchers involved in the large randomised controlled study recommend that guidelines for preventing blood clots such as deep vein thrombosis (DVT) and pulmonary embolism (PE) should be changed. They suggest that compression stockings should no longer be standard care for most patients having  planned surgery and taking anti-clotting medicine while in hospital. This could save the NHS in England around £63 million per year.

This research features in our Collection: 7 findings that could save the NHS money and improve care. Read the Collection

What’s the issue?

Surgery puts patients at risk of developing blood clots in the legs, known as deep vein thrombosis (DVT). The condition can cause swelling, skin problems and ulcers. Blood clots can also break away and travel to the lungs. This causes pulmonary embolism (PE), which can result in sudden death. Together, DVT and PE are known as venous thromboembolism (VTE).

Graduated compression stockings after surgery help prevent blood pooling and clotting in lower leg veins. Guidelines recommend their use in combination with anti-clotting medicines for patients with a moderate or high risk of VTE undergoing planned surgery.

In recent years, rates of VTE after surgery have fallen significantly thanks to improved care and drug therapy. Many clinicians are unconvinced that compression stockings are needed in addition to medication.

Compression stockings cost the NHS in England approximately £63 million per year. They can cause discomfort, pressure sores, blistering and other skin problems.

The GAPS study set out to determine whether the use of compression stockings is justified for preventing VTE in patients undergoing planned surgery and who receive anti-clotting medicine while in hospital.

What’s new?

The study recruited 1,858 adult patients at moderate or high risk of VTE. They were undergoing planned surgery at seven NHS hospitals between May 2016 and January 2019. Most patients were having gastrointestinal or obstetrics and gynaecology procedures.

Participants all received the anti-clotting drug, low weight molecular heparin. They were randomly split into two groups. Half also wore graduated compression stockings during their hospital stay. The others did not wear compression stockings during their hospital stay and were also asked not to wear them for 90 days after surgery.

Patients were scanned for blood clots in the legs 14 to 21 days after their operation. Symptoms of VTE triggered a leg or lung scan at any point during the trial.

The researchers found that heparin alone was as effective at preventing blood clots as the combination of medication and compression stockings:

  • VTE occurred in 1.4% of patients in the heparin plus stockings group
  • VTE occurred in 1.7% of patients in the heparin-only group
  • the difference in risk between the two groups was 0.3%, which was not significant
  • there was little or no difference in quality of life, side effects, and death from any cause between the two groups of patients.

Why is this important?

The results of the trial suggest that compression stockings after surgery are unnecessary for most patients undergoing planned operations who receive anti-clotting medicine while in hospital. This adds to a growing body of evidence questioning the use of graduated compression stockings for the prevention of VTE in certain clinical situations.

Given the risks and cost of using compression stockings, these findings suggest there is a need to review national and international guidelines for preventing hospital-associated VTE.

What’s next?

The researchers are planning more trials into the use of compression stockings in different clinical situations. They will look at whether wearing compression stockings in hospital reduces VTE in patients having hip or knee replacement surgery and other major abdominal and pelvic procedures. These operations have a higher risk of blood clots, and patients continue taking anti-clotting medicine for a period after leaving hospital. They will also examine the benefit of compression stockings in emergency surgical procedures, and in patients deemed to be at low risk of VTE.

You may be interested to read

The full paper: Davies AH, and others. Graduated compression stockings as adjuvant to pharmaco-thromboprophylaxis in elective surgical patients (GAPS study): randomised controlled trial. BMJ. 2020;369:m1309

Opinion piece on compression stockings by GAPS Trial Manager, Rebecca Lawton, BMJ Opinion blog

GAPS trial results video, YouTube

National Institute for Health and Care Excellence (NICE) guideline [NG89]: Venous thromboembolism in over 16s: reducing the risk of hospital-acquired deep vein thrombosis or pulmonary embolism (published: March 2018, last updated: August 2019)

Resources about venous thromboembolism, Thrombosis UK 

Funding: This study was funded by the NIHR Health Technology Assessment Programme. Several authors report additional grants from the NIHR. 

Conflicts of Interest: The study authors declared grants from public and private bodies. None were relevant to this study.

Disclaimer: Summaries on NIHR Evidence are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that the views expressed are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

NIHR Evidence is covered by the creative commons, CC-BY licence. Written content may be freely reproduced provided that suitable acknowledgement is made. Note, this license excludes comments made by third parties, audiovisual content, and linked content on other websites.

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