Subscribe UPGRADE NOW Gain full access to our premium coverage of pharmacy and medicines news and analysis Home News & analysis Cardiovascular disease Prevention of venous thromboembolism in hospitalised patients Clinical Pharmacist5 FEB 2019By Rebecca Walsh Pharmacists should note the National Institute for Health and Care Excellence’s updated guidance on use of pharmacological thromboprophylaxis in a range of hospitalised patient groups. Source: St Bartholomew’s Hospital / Science Photo Library Coloured angiograms taken from the front (left) and side (right) of a leg showing deep vein thrombosis in the calf. A thrombus is blocking the flow of blood (purple/pink) in the vein immediately to the right of the tibia (green) in the view at left Hospitalisation is known to increase the risk of developing venous thromboembolism (VTE) — a condition that most commonly includes deep vein thrombosis (DVT) or pulmonary embolism (PE). Hospital-acquired VTE, also known as hospital-associated or hospital-acquired thrombosis (HAT), causes a significant number of deaths and is estimated to cost the NHS £640m per year[1]. HAT is the leading cause of preventable hospital mortality in the UK[2] and includes any VTE that develops while a patient is in hospital or within 90 days of their discharge. Background incidence of VTE is estimated to be 1–2 per 1,000 of the population[3] and the incidence in the hospitalised patient population is considered to be around 3 per 1,000[4]. Several different factors are thought to increase the risk of developing VTE, some of which may be more likely to occur in the hospital setting. They are broadly categorised as prothrombotic changes to the blood, vascular wall injury and circulatory stasis (see Figure). Figure: Examples of thrombosis risk factors that are thought to increase the risk of developing venous thromboembolism in the hospital setting, as per Virchow’s triad Source: The Pharmaceutical Journal In 2005, the House of Commons Health Select Committee published a report highlighting the significance of the HAT burden on morbidity and mortality in the UK[1]. An expert working group on VTE prevention was formed in response, which published a proposed strategy to address the issue in 2007[5]. A national VTE risk-assessment tool was published in 2008[6]. Early 2018 saw the publication of the 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’[7]. NG89 was an update to and replacement of the NICE guideline CG92. There are several significant changes between the two, as highlighted in Table 1. This article summarises some of the changes made regarding the use of pharmacological thromboprophylaxis (TP) and, where available, briefly discusses the evidence base from which the recommendations were made. Table 1: Summary of the major differences between the National Institute for Health and Care Excellence guidelines CG92 and NG89 Area CG92 recommendation NG89 recommendation Scope of guideline The guideline applies to adults (defined as those aged 18 years and over) admitted to hospital. The guideline applies to all inpatients aged over 16 years and those presenting to emergency departments with lower limb immobilisation. The guidance refers specifically to acute psychiatric inpatients; guidance for pregnant/ postpartum women has been expanded on. Risk-assessment tool Healthcare professionals must use the risk criteria specified in the guideline. Heathcare professionals may use any tool published by a UK body, professional network or peer-reviewed journal. Timing of first venous thromboembolism (VTE) risk assessment This should be done on admission. This should be done as soon as possible after admission or by the time of first consultant review. Timing of reassessment of VTE risk This should be done within 24 hours of admission and whenever the clinical situation changes. This should be done at the point of consultant review or when the clinical situation changes. For postpartum women, this should be done within six hours of delivery (including miscarriage and termination of pregnancy). Timing of first dose of pharmacological thromboprophylaxis (TP) This should be done as soon as possible after risk assessment is complete. This should be done as soon as possible and within 14 hours* of admission. Minimum recommended duration of prophylaxis Prophylaxis should continue until the patient is no longer at an increased risk of VTE. Prophylaxis should continue for a minimum of seven days for all medical and most surgical patients. Patients with renal impairment The choice of pharmacological TP should be based on local policies and individual patient factors, including clinical condition (e.g. kidney failure). Healthcare professionals should use low-molecular-weight heparin or unfractionated heparin if pharmacological prophylaxis is indicated. If needed, reduce the doses for patients with renal impairment, in accordance with locally agreed protocols. Specific recommendations for subgroups of patients Medical Guidance is given for the following patient groups: general medical patients, patients who have had a stroke, patients who have cancer, patients receiving palliative care and patients with central venous catheters (CVCs) in situ. Guidance has been expanded to include acute coronary syndrome. The term “general” was replaced with “acutely ill” medical patients, and the term “stroke” was redefined as “acute stroke”. Changes to recommendations were made for patients with certain types of cancer. Reference to CVCs were removed. Surgical (non-orthopaedic) Guidance is given for the following patient groups: patients undergoing cardiac, gastrointestinal, gynaecological, thoracic, urological and neurological (cranial or spinal) surgery. Guidance has been expanded to include patients undergoing thoracic, vascular, oral and maxillofacial and ear, nose and throat surgery. Surgical (orthopaedic) Guidance is given for the following patient groups: patients who have had major trauma or spinal injuries, patients who are receiving critical care, and patients who are pregnant or up to six weeks postpartum. Guidance has been expanded to include patients with fragility fractures of the pelvis and proximal femur; patients undergoing nonarthroplasty orthopaedic knee surgery; and foot and ankle, and upper limb patients. The term “lower-limb casts” was replaced with “lower-limb immobilisation”. Other Guidance is given for the following patient groups: patients who have had major trauma or spinal injuries, patients who are receiving critical care, and patients who are pregnant or up to six weeks postpartum. “Postpartum” is now defined as referring to women who have had a baby, a miscarriage or a termination of pregnancy. *This is in line with the current NHS policy that states that all emergency admissions must be seen and have a thorough clinical assessment by a consultant within 14 hours of admission to hospital. Assessing and reassessing the risk of venous thromboembolism The updated NICE guideline recommends that all patients and pregnant women, women who have given birth, or who had a miscarriage or termination within the past six weeks, are risk assessed as soon as possible after admission to hospital or at the time of the first consultant review[7]. Unlike in the previous guideline, no risk-assessment criteria are stipulated in NG89. The NICE guideline committee reviewed evidence for several VTE risk-assessment tools and agreed there is a lack of good-quality evidence for any single tool, particularly in medical patients (with no evidence found to recommend a specific tool to use for pregnant women). While they acknowledged that neither the national tool nor the tool developed by the Royal College of Obstetricians and Gynaecologists (RCOG)[8] have been validated, and as there is concern that both lead to overprescribing of prophylaxis in certain patients, they recognised that these are the most widely used risk-assessment tools in the UK. Furthermore, no evidence was found for the effectiveness of any VTE risk tool specifically for reassessment. Therefore, the committee did not make any recommendation about the use of a specific tool for assessment or reassessment of risk.
