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)

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?

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.

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.

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.

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.

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.

Timelines for delivery: The trial will run for a total of 45 months including set-up, recruitment, follow-up and analysis.

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.