1.1.1.

Assess all patients to identify the risk of venous thromboembolism (VTE) and bleeding (see recommendations 1.1.2, 1.1.5, 1.1.9, 1.4.17 and 1.4.23)

People admitted to hospital

Medical patients

1.1.2.

Assess all medical patients to identify the risk of VTE and bleeding:

• as soon as possible after admission to hospital or by the time of the first consultant review
• using a tool published by a national UK body, professional network or peer-reviewed journal. The most commonly used risk assessment tool for medical patients is the Department of Health VTE risk assessment tool^mmm (See Appendix T). [2018]

1.1.3.

Balance the person’s individual risk of VTE against their risk of bleeding when deciding whether to offer pharmacological thromboprophylaxis to medical patients. [2018]

1.1.4.

If using pharmacological VTE prophylaxis for medical patients, start it as soon as possible and within 14 hours of admission, unless otherwise stated in the population-specific recommendations (see chapters 9–13). [2018]

1.

What is the accuracy of individual risk assessment tools in predicting the risk of VTE and risk of bleeding in medical patients admitted to hospital?

Predictive accuracy of VTE and bleeding risk tools

The committee was interested in the prognostic accuracy of risk assessment tools for medical patients admitted to hospital or who are in hospital having day procedures. A risk assessment tool would be used to identify people with an increased risk of VTE who would benefit from having VTE prophylaxis, or identify people with an increased risk of major bleeding in order to determine appropriate prophylaxis strategies, for example not giving pharmacological prophylaxis to people who are at a high risk of bleeding.

The committee agreed that sensitivity was more important than specificity in medical patients because people who are at higher risk of VTE could be identified for potential VTE prophylaxis treatment (fewer false negatives). The committee set thresholds for the acceptability of a test; for the populations noted here, these were ≥80% sensitivity and ≥60% specificity.

Some studies only reported a C-statistic. The committee acknowledged that this metric was important for comparing the overall accuracy of the tools, but in itself was unlikely to provide enough information on which to base a recommendation as it does not indicate the number of false positives and negatives of the tool. Therefore, the committee decided against recommending a tool without sensitivity and specificity data.

Clinical effectiveness of risk tools for reducing VTE

For the review of the clinical effectiveness of risk tools, the committee considered all-cause mortality, VTE (symptomatic or asymptomatic), DVT (symptomatic or asymptomatic), PE, fatal PE, major bleeding and quality of life as critical outcomes. The time points for these outcomes were up to 90 days from hospital discharge. The committee considered fatal bleeding, clinically relevant non-major bleeding, heparin-induced thrombocytopenia, hospital length of stay, unplanned readmission and haemorrhagic stroke as important outcomes. The time points for these outcomes were up to 90 days, apart from clinically relevant non-major bleeding up to 45 days from hospital discharge. Please see section 4.4.3 in the methods chapter for further detail on prioritisation of the critical outcomes.

Predictive accuracy of VTE and bleeding risk tools

Fourteen studies were identified looking at risk tools for predicting VTE in medical patients. Eight papers featured people admitted to hospital and six featured those having day procedures, all of whom were people coming into hospital to receive cancer treatment. One study was identified looking at a risk tool to predict the risk of major bleeding in hospitalised medical patients. PROBAST was used to assess the risk of bias. All these studies were at a high or very high risk of bias. Common reasons for this were papers only supplying retrospective validation, papers not reporting a clear definition or method of confirmation for the target condition (VTE, DVT, PE or major bleeding), papers not reporting the time-point for the target condition measurement, or unclear flow and timing between when the risk score was calculated and when the outcome was measured. There were also very low event rates in many of the studies and therefore not a reasonable number of outcome events compared to the number of factors in the risk tool. Many papers also failed to report all the relevant performance measures (sensitivity and specificity).

The committee were concerned about the applicability of some risk tools for UK practice due to the setting the tool was originally derived in as well as the location of the validation studies. The committee noted the differences in care settings and medical practices in the US and decided to downgrade any papers from a US setting for indirectness (see further detailed discussion on this in the following section).

Clinical effectiveness of risk tools for reducing VTE

No randomised controlled trials were identified, therefore observational studies were considered for inclusion in this review. Four observational studies were included in this review (one retrospective cohort study and three before-and-after studies). Two of the studies compared use of a risk tool versus with no risk tool (the National VTE Risk Assessment Tool [otherwise known as the Department of Health tool, please see the other considerations section for further detail] and the Padua Prediction Score); and two studies compared achieving the quality standard of 90% of admissions being assessed with the National VTE Risk Assessment Tool with not achieving the quality standard.

The committee discussed the need for caution when evaluating evidence from quality standard cohort papers and before-and-after studies due to the risk of bias inherent in these designs. The four observational studies provided evidence of very low quality due to risk of bias, primarily based on selection bias and incomplete outcome data; and imprecision around the effect estimates.

There is no established definition of medical patients, and the papers included in this review cover different groups of people including acutely ill medical patients, people who have had acute stroke and people with cancer; all with different associated thrombotic and bleeding risks. The rate of VTE identified in the evidence ranged from 0.5–4.5%. This large disparity is due to a number of factors, including: the heterogeneous group of patients; different study designs including RCT, prospective and retrospective cohorts and database/registry studies; and different definitions of the VTE endpoint (asymptomatic or symptomatic). Of the 18 studies reporting on risk tools in medical patients only three of these were undertaken in the UK NHS context. All three of these looked only at the National VTE Risk Assessment Tool (hereafter referred to as the National Tool) but none were designed specifically to validate whether this tool can adequately predict risk of VTE or risk of bleeding the UK population.

Evidence was identified for a number of VTE risk assessment tools for medical patients including the Padua prediction score, the Kucher score, the Intermountain score and the IMPROVE tool. Evidence was also identified for a bleeding risk version of the IMPROVE tool. The committee discussed these tools at length including the various risk factors that went into them and whether these were weighted or not. The committee noted that the National Tool and Intermountain score performed more like a checklist as they are not weighted tools but instead involve an in-or-out decision. The committee determined that none of the tools demonstrated sufficiently accurate performance for predicting VTE or bleeding risk based on the evidence, with none reaching the committee’s pre-specified sensitivity and specificity thresholds and many reporting only poor discrimination.

All committee members agreed that risk assessment is a critical part of the pathway for VTE prophylaxis. They also agreed that risk tools are beneficial in this process. However, in the absence of clear evidence there was disagreement about which tool to recommend. Based on its increasing use in the US context, initial discussions considered whether the IMPROVE Tool should be recommended over current practice, which is the National Tool.

There are two different versions of the IMPROVE tool. The 4-factor version of the tool is known as the predictive version because information on all 4 factors the tool measures should be available at admission and are considered to be predictive of VTE during the 3-month period following hospital admission.¹⁷⁹ The 7-factor version of the tool is known as the association version because some of the extra factors will require judgement of in-hospital factors that cannot be known for certain on admission (for example expected number of days the person might be immobilised) that are believed to be associated with an increased risk of VTE during the 3-month period following hospital admission.¹⁷⁹ Evidence included in this review is for the 4-factor version of IMPROVE as this was the only version with an identified validation study that met the inclusion criteria for the review. No validation studies of the 7-factor tool met the criteria in the review protocol.

The committee noted that the National Tool has been embedded in practice for 7 years with a high level of adherence. However, several committee members were of the opinion that the tool leads to over prescribing of prophylaxis in medical patients without clear evidence of benefit, potentially incurring a significant cost to the NHS. Around 73% of medical patients in the UK receive prophylaxis using the National Tool (NHS Safety Thermometer Data – March 2016 to March 2017, published April 12, 2017; accessed 15 August 2017) compared to around 40% of medical patients (in largely US based populations) for other tools.⁶⁴ The committee considered the high rate of prophylaxis being given was in part due to the way the National Tool is being used in practice. The National Tool may have become a ‘tick-box exercise’ where clinicians view it as a unweighted checklist of risk factors; if you tick one box (a single risk factor), that equates to a high VTE risk and this automatically results in prophylaxis being offered. The committee stressed that this has led to a larger number of medical patients receiving VTE prophylaxis than would be expected. Most importantly this fails to highlight the clinical judgement that must come into play in order to consider whether individual risk factors lead to an overall increased risk, and the balance of this with any bleeding risk factors or other contraindications. The committee understood that none of the identified tools, nor the currently practiced National Tool, offer clear guidance on how to balance VTE risk and bleeding risk to come to a decision on whether to offer prophylaxis, and if so what type. While the IMPROVE tool has both a VTE risk and bleeding risk version, both of which are available in online calculator format (beta version and no validation available), these also only provide a percentage risk for each outcome with no guidance on how to balance the two.

The committee also discussed the indirect context of the evidence for the IMPROVE tools (both the VTE risk version and the bleeding risk version). In particular the committee highlighted that in the US a much higher proportion of medical patients are cared for on intensive care wards (ICU), whereas in the UK it is only the very ill (generally those in need of artificial ventilation) who are moved to critical care – so the baseline condition of the two populations would be very different. The 7-factor version of the IMPROVE tool has ICU/CCU stay as a major risk component and this would contribute to different risk assessment interpretations in the UK compared to the US population in which the tool is validated. The committee also acknowledged that the average length of stay in intensive care is around 7 days in the USA, compared to a shorter stay of approximately 2–3 days in the UK. This is reflected in the National Tool listing mobility significantly reduced ≥3 days as a risk, and the 7-factor IMPROVE tool listing immobilisation ≥7 days as a risk. Factors such as these require the clinician to make judgements about anticipated patient features that cannot be known with certainty at admission. The committee pointed out that tools that require information that may not be available at the point of admission are not practical.

Overall, the committee agreed that there is a lack of good quality evidence for any tool. The following options were considered as recommendations for assessing risk in medical patients:

(1)

use the National Tool

(2)

use the IMPROVE Tool

(3)

use either the National Tool or the IMPROVE Tool

(4)

consider medical patients at risk if immobility was a factor and they have an additional risk factor, with individual risk factors being provided as examples in a box;

(5)

use an existing derived or validated tool or checklist.

After considerable debate a committee meeting consensus was reached to rule out the first 3 options. However, no consensus was reached on whether to recommend options number 4 or 5. The main arguments behind supporting each of these options were:

• Those favouring option 4 expressed concerns with recommending option 5. They were concerned about organisational rigour in a resource-stretched NHS and that the decision on which tool to use will be made that may not be in the patient’s best interest. A particular tool may be chosen because of potential cost saving benefit and not because it is considered to be more accurate or effective.
• Those favouring option 5 believed it better reflects the uncertainty in evidence as there is no clear evidence that one tool is better than another. It allows clinicians to decide which tool to use whereas option 4 seemed too similar to current practice. It would also prompt clinicians to consider that risk assessment for VTE is not just a checklist of risk factors that once ticked automatically mean prophylaxis, it is a balance between VTE risk and bleeding risk which requires clinical judgement before the decision to offer prophylaxis is made.

Because of the split decision the committee voted for one of these two options and agreed whichever option had the most votes would determine the recommendation. The vote produced a majority favouring option 5. Following stakeholder consultation the committee also decided to acknowledge in the recommendation that the most commonly used VTE risk assessment tool for hospital patients in the NHS is the National Tool (see appendix T).

Reflecting the uncertainty in the evidence for one risk tool over another, the committee prioritised a research recommendation in this area.

Two economic studies were included. One of the studies compared the use of a risk assessment tool for medical patients based on the PRETEMED scale (a validated risk stratification tool for medical patients) which was integrated in the hospital electronic system in the form of an e-alert system. The second study assessed the impact of restricting the provision of LMWH prophylaxis based on a list of risk factors that allow restricted, intermediate or broad eligibility for prophylaxis in general medical patients admitted to hospital. The committee discussed the two studies and noted that the study that compared using a risk assessment tool to not using one showed that the use of a risk assessment tool was dominant (both more effective and less costly). The committee acknowledged however that the tool used in this study was not validated and was not one of those identified in the clinical review.

The committee highlighted that all the risk tools included in the clinical review are generally not associated with any licencing cost although some may require a specific software installation. However, the committee acknowledged that the prognostic performance of the risk tool, as well as the baseline risk in the target population, would determine the number of individuals who would receive prophylaxis. The choice of a tool that has high specificity would minimise the cost of unnecessary prophylaxis provision. If the specificity of a tool is low, there is a risk that a large number of people will be triggered for further care that they do not require (over-treatment), which would make the tool unlikely to be cost-effective. Conversely, if the tool has low sensitivity then a large number of people will not be identified as being at risk of VTE, and therefore not receive the prophylaxis they could benefit from. The committee determined that the evidence for the prognostic accuracy of the tools identified was inconclusive and does not support recommending one tool over another. This increases the uncertainty in the cost effectiveness of these tools.

The committee acknowledged that the use of the National Tool is considered current practice for surgical, medical and trauma patients. Hence, any changes are likely to have cost impact.

For medical admissions, the committee discussed the potential of using the IMPROVE tool, both the 4- and 7- factor versions; however there were concerns about the fact that neither has been validated in a UK population. Furthermore, the tool mainly assesses the risk of symptomatic VTE and does not identify patients at risk of developing an asymptomatic DVT.

A cost impact analysis was also undertaken to aid the committee’s decision making. This analysis showed that using the IMPROVE risk assessment tool would result in around 40% of people having prophylaxis, in line with the intermediate eligibility group in the Miller study. The saving from this reduction in prophylaxis is estimated to be around £22.3 million.

However after the extensive discussions and voting process outlined above, it was determined that the evidence underpinning the accuracy and effectiveness of IMPROVE and all the tools considered for medical patients (including the National Tool) did not show that one tool is better than the other and a research recommendation was made to allow for future research to address the uncertainty in this area.

The National VTE Prevention Programme was launched in England in 2010 mandating VTE risk assessment in all adult patients admitted to an acute hospital, using a National VTE risk assessment tool.¹⁶¹ The committee noted that CG92 and the National Tool were published concurrently in 2010, therefore CG92 did not recommend the National Tool by name. However, it was also noted that the recommendation in CG92 and the National Tool is identical.

The initial goal as part of the Commissioning for Quality Innovation (CQuIN) Framework was to set a 90% target of all patients risk assessed for VTE. This was supported by a financial incentive (CQuIN) payment and within 3 years this goal was increased to 95% which has been exceeded in subsequent years.¹⁶¹ However the committee noted that there have been no published studies examining the longterm impact of the National VTE prevention programme, specifically no research has been conducted validating the National Tool’s performance at predicting medical patients’ risk of VTE and risk of bleeding. The committee expressed their disappointment in this, especially as this was an area highlighted for further research by the CG92 committee.

The committee made a high-priority research recommendation on risk assessment tools; see appendix R for more details. The committee discussed giving guidance on the appropriate time to initiate pharmacological prophylaxis following completion of the risk assessment. In particular the committee wanted to highlight that, if using pharmacological prophylaxis, it should be given in a timely manner to ensure that people are not left for too long without it if they happened to be admitted shortly after what is usually a set daily time for doses to be given on a ward. The committee recommend a time point that is in line with current NHS policy on time to consultant review of acute inpatients. This standard states that all emergency admissions must be seen and have a thorough clinical assessment by a suitable consultant as soon as possible, but at the latest within 14 hours from the time of admission to hospital.¹³⁴ The committee agreed that recommending a similar timeframe within which pharmacological prophylaxis should be given (if indicated by risk assessment) makes logical clinical sense and will ensure clinical care is not delayed.

Surgical and trauma patients

1.1.5.

Assess all surgical and trauma patients to identify the risk of VTE and bleeding:

• as soon as possible after admission to hospital or by the time of the first consultant review
• using a tool published by a national UK body, professional network or peer-reviewed journal. The most commonly used risk assessment tool for surgical patients is the Department of Health VTE risk assessment toolⁿⁿⁿ (See Appendix T). [2018]

1.1.6.

Balance the person’s individual risk of VTE against their risk of bleeding when deciding whether to offer pharmacological thromboprophylaxis to surgical and trauma patients. [2018]

1.1.7.

If using pharmacological VTE prophylaxis for surgical and trauma patients, start it as soon as possible and within 14 hours of admission, unless otherwise stated in the population-specific recommendations (see chapters 9–13). [2018]

1.

What is the accuracy of individual risk assessment tools in predicting the risk of VTE and risk of bleeding in surgical and trauma patients admitted to hospital?

Predictive accuracy of VTE and bleeding risk tools

The committee was interested in the prognostic accuracy of risk assessment tools for surgical and trauma patients admitted to hospital or who are in hospital having daycase surgery. A risk assessment tool would be used to identify people with an increased risk of VTE who would benefit from having VTE prophylaxis, or identify people with an increased risk of major bleeding in order to determine appropriate prophylaxis strategies, for example not giving pharmacological prophylaxis to people who were at a high risk of bleeding.

The committee agreed that sensitivity was more important than specificity in surgical patients because people who are at higher risk of VTE could be identified for potential VTE prophylaxis treatment (fewer false negatives). The committee set thresholds for the acceptability of a test; for the populations noted here, these were ≥80% sensitivity and ≥60% specificity.

Some studies only reported a C-statistic. The committee acknowledged that this metric was important for comparing the overall accuracy of the tools, but in itself was unlikely to provide enough information on which to base a recommendation as it does not indicate the number of false positives and negatives of the tool. Therefore, the committee decided against recommending a tool without sensitivity and specificity data.

Clinical effectiveness of risk tools for reducing VTE

For the review of clinical effectiveness of risk tools, the committee considered allcause mortality, VTE (symptomatic or asymptomatic), DVT (symptomatic or asymptomatic), PE, fatal PE, major bleeding and quality of life as critical outcomes. The time points for these outcomes were up to 90 days from hospital discharge. The committee considered fatal bleeding, clinically relevant non-major bleeding, heparininduced thrombocytopenia, hospital length of stay, unplanned readmission and haemorrhagic stroke as important outcomes. The time points for these outcomes were up to 90 days, apart from clinically relevant non-major bleeding up to 45 days from hospital discharge. Please see section 4.4.3 in the methods chapter for further detail on prioritisation of the critical outcomes.

Predictive accuracy of VTE and bleeding risk tools

Fifteen studies were identified looking at risk tools for predicting VTE in surgical or trauma patients. Fourteen papers featured people admitted to hospital (10 for surgery, 3 for trauma and 1 for burn injuries) and one featured people in hospital for day-case surgery. No studies were identified looking at risk tools to predict the risk of major bleeding in surgical or trauma patients. PROBAST was used to assess the risk of bias. All of these studies were at a high or very high risk of bias. Common reasons for this were papers only supplying retrospective validation, papers not reporting a clear definition or method of confirmation for the target condition (VTE, DVT, PE or major bleeding), papers not reporting the time-point for the target condition measurement, or unclear flow and timing between when the risk score was calculated and when the outcome was measured. There were also very low event rates in many of the studies and therefore not a sufficient number of outcome events compared to the number of factors in the risk tool. Many papers also failed to report all the relevant performance measures (sensitivity and specificity). The committee were concerned about the applicability of some risk tools for UK practice due to the setting the tool was originally derived in as well as the location of the validation studies. The committee noted the differences in care settings and medical practices in the US and decided to downgrade any papers from a US setting for indirectness. In particular, the committee highlighted that in the US a much higher proportion of surgical patients are cared for on intensive care wards (ICU), whereas in the UK it is only the very ill (generally those in need of artificial ventilation) who are moved to critical care – so the baseline condition of the two populations would be very different. The committee also considered that the average length of stay in intensive care is around 7 days in the US, compared to a shorter stay of approximately 2–3 days in the UK.

Clinical effectiveness of risk tools for reducing VTE

No randomised controlled trials were identified, therefore observational studies were considered for inclusion in this review. Two observational studies were included in this review (one retrospective cohort study and one before-and-after study). One compared use of the Caprini risk assessment model with no risk assessment tool and one study compared achieving the quality standard of 90% of admissions being assessed with the National VTE Risk Assessment Tool (otherwise known as the Department of Health tool, please see the other considerations section for further detail) with not achieving the quality standard.

The committee discussed the need for caution when evaluating evidence from quality standard cohort papers and before-and-after studies due to the risk of bias inherent in these designs. The two observational studies provided evidence of very low quality due to risk of bias, primarily based on selection bias and incomplete outcome data. There was imprecision around the effect estimates, and the evidence on the Caprini risk assessment model was also downgraded for indirectness due to the setting being in the US hospital system where practice differs from the UK context.

Evidence for risk assessment tools came from a very wide range of surgical populations, including abdominal, colorectal, lung, neuro, oesophageal, plastic, and urological surgery; as well as mixed surgical populations, trauma patients and those undergoing day-case surgery (surgical outpatients); all with different associated thrombotic and bleeding risks. The rate of VTE identified in the evidence ranged from 0.33–27.9%. This very large disparity is due to a number of factors including the heterogeneous group of patients and surgery-associated VTE risk; different study designs including RCT, prospective and retrospective cohorts and database/registry studies; and different definitions of the VTE endpoint (asymptomatic or symptomatic). Of the 17 studies reporting on risk tools in surgical and trauma patients only one was undertaken in the UK NHS context. This UK study looked at the National VTE Risk Assessment Tool (hereafter referred to as the National Tool) but was not designed specifically to validate whether this tool can adequately predict risk of VTE or risk of bleeding in the UK surgical population.

Evidence was identified for a number of VTE risk assessment tools including the Caprini risk assessment model, the American College of Surgeons National Surgical Quality Improvement Programme (ACS NSQIP) Universal Surgical Risk Calculator (not specific to the outcome of VTE) and the Trauma Embolic Scoring System (TESS). No tool was identified to assess the risk of bleeding. The majority of the evidence was found for the Caprini risk assessment model, which is a weighted tool made up of an extensive list of risk factors. Low and very low quality evidence from some highly specific surgical populations (lung cancer, oesophageal cancer, and high-risk abdominal and neurosurgical) suggested that the Caprini risk assessment model reached the committee’s thresholds for consideration for both sensitivity and specificity when using cut-offs such as ≥9, ≥10.5 and ≥15. The low and very low evidence from these studies suggested the tools showed moderate discrimination for predicting VTE. Very low quality evidence from the clinical effectiveness review also suggested a reduction in DVT rates when using the Caprini risk assessment model compared to using no formal risk assessment.

All committee members agreed that risk assessment is a critical part of the pathway for VTE prophylaxis. They also agreed that risk tools are beneficial in this process. Based on the evidence, initial discussions considered whether the Caprini risk assessment model should be recommended over current practice, which is the National Tool. The committee highlighted that there was not thought to be the same issue within the surgical population as that recognised in the medical population (use of the National Tool leading to giving too much prophylaxis). However, they acknowledged that the National Tool has not been validated in any surgical population or in people with trauma. While the evidence suggested the Caprini risk assessment model could be beneficial, the evidence was of low to very low quality and was only validated in highly specific surgical populations and the committee could not be sure that these findings could be generalised to the wider ‘mixed’ surgical population. There was also concern that the Caprini risk assessment model has almost exclusively been validated only in a US population, and never in the UK population.

Following decisions on the recommendation for risk assessment in medical patients, the committee discussed whether it was conceptually feasible to recommend different risk assessment tools for the surgical and trauma patients as for the medical patients. They highlighted that the distinction between these two populations is becoming increasingly blurred in the current UK context as surgical patients will increasingly be older and/or have more medical comorbidities (increasing rates of life-style diseases such as obesity, non-alcoholic fatty liver disease and diabetes). This was also discussed in the context of day-case or outpatient surgery. This covers a mix of minor procedures and as technology improves, and surgeons have access to innovative technologies, surgical time will be reduced and an increasing amount of surgical procedures will become day cases. For this population the VTE and bleeding risk may not necessarily be related to the surgical procedure, but instead be related to the pre-surgical context (for example their medical status).

The committee agreed that it was logical and advisable to have the same risk assessment recommendation for the surgical and trauma population as for the medical population. They also considered that the question of risk assessment tools for the surgical and trauma population was a key priority for future research alongside the research recommendation for risk assessment tools in the medical population. Following stakeholder consultation the committee also decided to acknowledge in the recommendation that the most commonly used VTE risk assessment tool for hospital patients in the NHS is the National Tool (see appendix T).

One economic study was included. This compared the use of a risk assessment tool based on using ACCP guidelines for surgical patients which were integrated in the hospital electronic system in the form of an e-alert system. The committee discussed the study and noted that, similar to the general medical population in the study, the use of a risk assessment tool for surgical patients was dominant (both more effective and less costly).

The committee noted that all the risk tools included in the clinical review are generally not associated with any licencing cost although some may require a specific software installation. However, the committee agreed that the evidence for the tools identified was inconclusive and does not support recommending one tool over another. The committee acknowledged that the use of the National Tool for both surgical and trauma patients is currently embedded in NHS practice. However, in contrast to the case in medical patients, the committee did not feel that this tool led to over-prescribing of prophylaxis in the surgical population given the higher baseline risk of VTE compared to general medical patients. The committee also acknowledged that changing from the use of the National Tool to any other tool is likely to have a cost impact to allow the integration of a new tool into practice, which would require robust evidence in terms of clinical and cost effectiveness to support it. The current status of the retrieved evidence did not offer a strong base for recommending any of the identified tools.

The committee discussed the potential of using the Caprini tool, however there were concerns about the fact that it has not been validated in a UK population and also that it has only been validated in a small number of surgical specialities. After the extensive discussions and voting process outlined in the discussion on risk assessment in medical patients, it was determined that the evidence underpinning the accuracy and effectiveness of all the tools considered for the surgical and trauma populations did not show that one tool is better than the other and a research recommendation was made to allow for future research to address the uncertainty in this area.

The National VTE Prevention Programme was launched in England in 2010 mandating VTE risk assessment in all adult patients admitted to an acute hospital, using a National VTE risk assessment tool.¹⁶¹ The committee noted that CG92 and the National Tool were published concurrently in 2010, therefore CG92 did not recommend the National Tool by name. However, it was also noted that the recommendation in CG92 and the National Tool is identical.

The initial goal as part of the Commissioning for Quality Innovation (CQuIN) Framework was to set a 90% target of all patients risk assessed for VTE. This was supported by a financial incentive (CQuIN) payment and within 3 years this goal was increased to 95% which has been exceeded in subsequent years.¹⁶¹ However the committee noted that there have been no published studies examining the longterm impact of the National VTE prevention programme, specifically no research has been conducted validating the National Tool’s performance at predicting surgical and trauma patients risk of VTE and risk of bleeding. The committee expressed their disappointment in this, especially as this was an area highlighted for further research by the CG92 committee.

The committee made a high-priority research recommendation on risk assessment tools; see appendix R for more details.

The committee discussed giving guidance on the appropriate time to initiate pharmacological prophylaxis following completion of the risk assessment. In particular the committee wanted to highlight that, if using pharmacological prophylaxis, it should be given in a timely manner to ensure that people are not left for too long without it if they happened to be admitted shortly after what is usually a set daily time for doses to be given on a ward. The committee recommend a time point that is in line with current NHS policy on time to consultant review of acute inpatients. This standard states that all emergency admissions must be seen and have a thorough clinical assessment by a suitable consultant as soon as possible, but at the latest within 14 hours from the time of admission to hospital.¹³⁴ The committee agreed that recommending a similar timeframe within which pharmacological prophylaxis should be given (if indicated by risk assessment) makes logical clinical sense and will ensure clinical care is not delayed.