1.5.34.

Offer mechanical VTE prophylaxis with intermittent pneumatic compression on admission to people with serious or major trauma. Continue until the person no longer has significantly reduced mobility relative to their normal or anticipated mobility. [2018]

1.5.35.

Reassess risk of VTE and bleeding in people with serious or major trauma whenever their clinical condition changes and at least daily. [2018]

1.5.36.

Consider pharmacological VTE prophylaxis for people with serious or major trauma as soon as possible after the risk assessment when the risk of VTE outweighs the risk of bleeding. Continue for a minimum of 7 days. [2018]

The committee considered all-cause mortality (up to 90 days from hospital discharge), deep vein thrombosis (symptomatic and asymptomatic) (up to 90 days from hospital discharge), pulmonary embolism (symptomatic and asymptomatic) (up to 90 days from hospital discharge), fatal PE (up to 90 days from hospital discharge), and major bleeding (up to 45 days from hospital discharge) as critical outcomes.

The committee considered clinically relevant non-major bleeding (up to 45 days from hospital discharge), health-related quality of life (up to 90 days from hospital discharge), heparin-induced thrombocytopaenia (duration of study), and technical complications of mechanical interventions (duration of study) as important outcomes.

Please see section 4.4.3 in the methods chapter for further detail on prioritisation of the critical outcomes.

Ten studies were included in this review. Four were included in the previous guideline (CG92) and six were new studies. A total of thirteen comparisons were identified from the ten included studies, evaluating mechanical (IPCD, AES, continual passive motion and foot pump) and pharmacological (UFH and LMWH) interventions for VTE prophylaxis.

The committee discussed that the generalisability of evidence from studies to individual patients should be considered. The trials included moderate to severe trauma patients with a wide range of ISS levels reported (if at all) and a variety of injuries, with the more severe patients usually managed in specialised trauma centres. There is a range of risks for VTE and bleeding, depending on the type, location and severity of the injuries. The majority of the evidence was downgraded due to risk of bias based on inadequate randomisation and allocation concealment. Much of the evidence was further downgraded due to imprecision. In cases where major bleeding was not adequately defined, the evidence from these studies was also downgraded for indirectness of the outcome.

The committee noted that the high event rate for DVT and PE in this population compared to some of the other review populations is expected. This tallies with clinical experience; it is common for ICU populations to experience higher rates of DVT and PE. Therefore clinicians are likely to be comfortable with the idea of administering VTE prophylaxis in this population. The committee noted that the trauma population are likely to have significant immobilisation due to the nature of their injuries which would contribute to an increased risk for VTE.

Evidence was identified for both mechanical and pharmacological prophylaxis both compared to each other and to no VTE prophylaxis. When considering the evidence for mechanical prophylaxis, the committee noted that the evidence showed some possible clinical benefits of IPCD alone or in combination with AES for the outcomes of all-cause mortality, DVT and PE, however there was uncertainty around these results consistent with no difference, or harm. There were seven comparisons of mechanical versus pharmacological prophylaxis. This evidence demonstrated conflicting findings, with some suggesting clinical benefits of mechanical prophylaxis or combined mechanical and pharmacological prophylaxis for DVT, PE and fatal PE, and other evidence demonstrating clinical benefits of pharmacological prophylaxis for DVT.

The committee discussed that for the major trauma population, the risk of bleeding is high, and therefore mechanical prophylaxis may be preferable. It was also noted that AES are not always practical in the major trauma population, due to the nature of the injuries which may prevent AES from being worn (for example injuries involving broken legs). The committee discussed different prophylaxis strategies including immediate combined mechanical and pharmacological prophylaxis or initial mechanical and then switching to pharmacological once bleeding risk had minimised. While the review sought to find any differences between the effectiveness of IPCD and foot-pumps, in practice foot-pumps are understood to be a subset (type) of intermittent pneumatic compression device, specifically shaped for the foot only. The committee considered that the evidence did not clearly demonstrate clinical superiority of half- or full-leg based IPCD compared to foot pumps and therefore decided it was reasonable to group all such devices under the more general term of intermittent pneumatic compression. The committee concluded that mechanical prophylaxis such as IPCD and foot pumps should be recommended as initial treatment, until the risk of bleeding is reduced, at which time the risk of bleeding should be weighed against the risk of VTE. Given the lack of evidence for AES alone and the practical issues surrounding its use, the committee concluded that AES would not be recommended.

There were two pharmacological prophylaxis only comparisons. When UFH was compared to no prophylaxis, possible clinical benefits of UFH were seen for all-cause mortality, DVT and PE. However, when UFH was compared to LMWH, the evidence was mixed and therefore the committee considered that there was insufficient evidence to specify which type of pharmacological prophylaxis was most effective for this population. It was highlighted that if necessary (for example reoperation) anticoagulation with UFH can be reversed, unlike with LMWH or fondaparinux. The committee concluded that pharmacological prophylaxis should be considered for major trauma patients, but did not specify which type of pharmacological prophylaxis should be used. The particular prophylaxis preparation used would need to be based on clinical judgement on consideration of the individual patient factors. The committee also discussed whether pharmacological prophylaxis should be given in addition to or as an alternative to mechanical prophylaxis, however it was agreed that this would need to depend on a clinical judgement taking into account the individual patient.

Two economic studies have been included in this review. One study comparing LMWH to UFH was previously included in CG92. The second study compared VCFs to IPCDs in trauma patients who have contraindications to pharmacological prophylaxis. Both studies were assessed as partially applicable with potentially serious limitations.

The committee discussed the economic evidence alongside the clinical evidence. It was acknowledged that the serious and major trauma populations are at very high risk of bleeding, hence mechanical prophylaxis options will have a more favourable benefit-harm balance, particularly in the early stages of the trauma event. The economic evidence presented supported the cost effectiveness of IPCD and showed that it was a cost saving option compared to VCFs in people who have contraindication to pharmacological prophylaxis. The committee considered that, based on the evidence presented and their collective clinical experience, the use of VCFs for primary prevention of VTE in this population is not a cost-effective use of resources. They also acknowledged that the removal of VCF incurs extra cost that has not been included in the economic evidence presented and this is likely to make VCFs even more costly. Hence, the committee chose to recommend against their use for the purpose of primary VTE prevention in this population. For people at low risk of major bleeding, the committee considered that the benefit of pharmacological prophylaxis in the prevention of VTE is likely to outweigh their risks. Therefore, the committee considered the addition of pharmacological prophylaxis in this group to be a cost-effective use of resources and likely to be off-set through the prevention of costly VTE events.

It was noted that the studies included in this review include populations with varying degrees of injury severity. Initially the committee considered including only those papers with patients with major trauma defined as Injury Severity Score ≥16.¹⁵ However in keeping in line with the NICE Major Trauma guideline (https://www​.nice.org.uk/guidance/ng39) this definition was extended to include major trauma by definition of included study. The committee discussed that in the UK context having an ISS of ≥9 gets patient details entered onto TARN (trauma audit and research network). Once the ISS is getting into the high teens this represents multi-system injuries.

The committee highlighted that reassessment of VTE and bleeding risk needed to happen on an at least daily basis in this population due to the nature of their injuries and evolving risk profile.

The committee also considered the use of vena caval filters, however due to the lack of clinical evidence and the presence of economic evidence demonstrating it not to be cost effective it was decided not to recommend this method of prophylaxis.

For people undergoing neurosurgery as a result of a head injury see the recommendations relating to cranial surgery in section 32.6.