Title: Examining the benefit of graduated compression stockings in the Prevention of vEnous Thromboembolism in low-risk Surgical patients: a multicentre cluster randomised controlled trial (PETS Trial)
Funder: Department of Health and Social Care

Abstract: Background to the research_x000D_ Hospital acquired thrombosis is a term used to describe blood clots that may form in the legs and lungs after someone is treated in hospital. A clot in the leg can cause swelling, pain and other long-term problems, such as a leg wound (ulcer). If a clot in the leg breaks off and travels to the lungs, it can cause problems with the lungs' ability to transfer oxygen from the air into the blood and may be life threatening. Having surgery increases a person's risk of developing blood clots. There are a number of reasons for this including being unwell, being unable to move during surgery, and moving around less after surgery. To reduce the chance of a blood clot developing, doctors can give blood-thinning medications and elastic stockings that squeeze the leg muscles._x000D_ _x000D_ People having short stay surgery are those who are able to go home the same day or those who stay overnight but go home shortly afterwards. These people are at much lower risk of developing a blood clot than those who stay in hospital for longer. These low-risk people are often given elastic stockings to reduce the chance of developing a blood clot. The risks of wearing the stockings are very low but wearing stockings can be uncomfortable. Occasionally some people with poor blood supply to their feet, can develop wounds on one or both of their feet after wearing elastic stockings, but this is rare. In the UK, there are over a million short stay surgeries performed each year and most of these people are given elastic stockings to wear. Collectively, these elastic stockings cost the NHS a lot of money and it remains unknown if they benefit these people._x000D_ A recent study in a different group of people, who are at higher risk of developing a blood clot and are usually given blood-thinning medications, showed that elastic stockings offered no additional benefit compared to just having blood-thinning medications alone. There are currently no up to date studies specifically in this group of people that look at whether these elastic stockings reduce the chance of developing a blood clot._x000D_ _x000D_ Aim of the research_x000D_ The purpose of this study is to investigate if it is worthwhile to continue using elastic stockings in people having surgery where the risk of developing blood clots is low. _x000D_ _x000D_ Design and methods used_x000D_ People enrolled in the study will be over the age of 18. All participants will be checked for their risk of blood clots when they arrive in hospital for surgery. This study will only include people where the check shows a low risk of developing blood clots, which will be assessed using a nationally recognised tool. At random, participants will be given elastic stockings to wear during their time in hospital or not given elastic stockings at all. The surgery itself and all other processes will continue as normal. _x000D_ _x000D_ Participants will be contacted at 7 and 90-days after their surgery (via telephone, email or SMS) to see how they are getting on and to see if they developed a blood clot. Participants will be provided with information on the signs and symptoms of blood clots, such as a swollen painful leg. They will be advised to attend the emergency department if they develop any of the signs and symptoms, and not wait for the follow-up to avoid delay. If the doctors and nurses suspect a participant has developed a blood clot, they will come to hospital for extra tests and treatment which is best practice if a blood clot is suspected.

Lay abstract: Research question: Are graduated compression stockings (GCS) effective in the reduction of hospital-acquired venous thromboembolism (VTE) in surgical patients undergoing short-stay procedures deemed to be at low-risk of VTE in comparison to no prophylaxis?_x000D_ _x000D_ Background: The UK annual VTE-related mortality is estimated to be up to 32,000 fatalities, with associated annual costs as high as £640 million. Surgery is an established risk factor for VTE, with an estimated untreated risk of 10-40% for most open general surgical procedures. Hospital-acquired thrombosis (HAT) is defined as any VTE-related event, including deep vein thrombosis (DVT) and pulmonary embolism (PE) within 90 days of hospital admission. The National Institute for Health and Care Excellence (NICE) guidelines for the prevention of VTE (2007) previously recommended that all surgical patients should receive GCS to reduce the risk of VTE. Updated guidelines instead recommend that all patients undergoing abdominal, thoracic, spinal, bariatric, head and neck, and elective joint surgery be treated with GCS and to consider treatment for all those undergoing cardiac, vascular and ear, nose and throat surgery. The result of these guidelines is that patients undergoing short-stay procedures who are able to ambulate early and have no other thrombosis risk factors are still treated with GCS._x000D_ A search of National Health Service (NHS) Hospital Episode Statistics data revealed 1,038,943 operations compatible with day case procedures (e.g. inguinal hernia repair) undertaken in the year 2018-2019. The cost of purchasing and applying GCS equates to £22.46. We estimate the costs of GCS for day case operations alone to be £23.3 million per annum. Evidence for the use of GCS in VTE prevention for low VTE risk surgical patients is poor - a recent systematic review failed to identify any randomised-controlled trials (RCTs) investigating this._x000D_ _x000D_ Aims and objectives: The aim of this study is to evaluate the benefit of GCS in the prevention of VTE in patients undergoing short-stay surgical procedures assessed as being at low-risk for VTE._x000D_ _x000D_ Methods: We propose an assessor-blind multicentre cluster design RCT aiming to determine whether GCS is superior in comparison to no GCS in the prevention of VTE for surgical patients undergoing short-stay procedures assessed to be at low-risk of VTE._x000D_ A total of 50 sites (21,472 participants) will be randomised to either GCS or no GCS. Inclusion criteria stipulates participants are adult, undergoing short stay procedures, and deemed low-risk for VTE as per the Department of Health risk assessment tool. The primary outcome will be rate of symptomatic VTE, i.e. DVT or PE within 90 days. Follow-up will be at 7 and 90 days via telephone or completion of an online questionnaire._x000D_ _x000D_ Timelines for delivery: The trial will run for a total of 45 months including set-up, recruitment, follow-up and analysis._x000D_ _x000D_ Anticipated impact and dissemination: This trial will provide evidence to guide widespread clinical practice and will facilitate an update of national and international guidelines. If the trial were to find GCS ineffective, then providers would recommend against their use. This would lead to a subsequent re-allocation of resources which is estimated to be as much as £23.3 million per annum. We anticipate publication in a high-impact journal, presentation at international conferences and dissemination on the Imperial College London, NIHR and Thrombosis UK websites and other media stream.

Research activity codes: 6.3 MEDICAL DEVICES
Health categories: CARDIOVASCULAR