NICE NG89 recommendations for extended pharmacological thromboprophylaxis – is it justified and is it cost effective: a rebuttal from the British Society for Haematology

We are writing to express our collective concern about the recommendation in the National Institute for Health and Care Excellence (NICE) guideline [NG89] (, requiring a minimum of 7 days pharmacological thromboprophylaxis for all medical patients and surgical patients assessed to be at increased risk of venous thromboembolism (VTE). With the exception of certain high‐risk groups (e.g. abdominal cancer surgery, hip fracture and joint replacement) the vast majority of patients currently continue pharmacological thromboprophylaxis only until discharge from hospital. Our concerns relate to the following points.

  1. Is the recommendation justified by evidence?
  2. Is the guideline deliverable within the National Health Service (NHS)?

Is the new recommendation justified by evidence?

With regard to whether the new recommendation is justified by evidence, it is not clear how the guideline committee concluded that pharmacological prophylaxis should be administered for a minimum of 7 days. In the landmark low molecular weight heparin (LMWH) studies of thromboprophylaxis in medical patients, MEDENOX (Samama et al, 1999) and PREVENT (Leizorovicz et al, 2004), enoxaparin and dalteparin were administered for 6–14 and 14 days respectively. In the recently published MARINER study (Spyropoulos et al, 2018), LMWH was administered for 3−10 days. The choice of 7 days appears to be arbitrary, rather than based on the evidence available.

No studies of thromboprophylaxis in medical patients have shown a reduction in mortality. In some of the studies there was a non‐significant reduction in symptomatic deep vein thrombosis, but this is offset by an increased risk of clinically relevant bleeding. An analysis of the number needed to treat in the MEDENOX study concluded that administration of LMWH to 300 medical patients in hospital would prevent 3 pulmonary emboli but cause 2 severe bleeds (Calderon et al, 2000). An inclusion criterion for this study was an anticipated hospital stay of at least 6 days. The risk benefit when applying the same duration of thromboprophylaxis to a patient group with a far shorter length of stay is unknown. Current American College of Chest Physicians guidelines advise against extended post‐discharge LMWH for medical patients, because of the increased risk of bleeding (Kahn et al, 2012).

A similar argument can be made for the majority of surgical patients. Collins et al (1988) reviewed multiple surgical trials of thromboprophylaxis with low dose heparin, confirming a reduction in clinically relevant VTE events by two thirds. However, many of the non‐orthopaedic surgical trials did not require a full 7 days of prophylaxis and had no requirement to continue beyond discharge from hospital. In the largest study by Kakkar et al (1975), patients that were randomised to low dose heparin were those ‘who required a hospital stay of at least 7 days’.

A further key point is that the current national VTE risk assessment tool used to assess whether surgical and non‐surgical patients admitted to hospital in England require pharmacological thromboprophylaxis uses a far lower threshold for risk in comparison with all the published studies on thromboprophylaxis. For example, age 60 years or body mass index ≥30 are alone sufficient to trigger intervention using this national tool, which has never been validated by randomised trials. ( Forcing extended thromboprophylaxis in large groups of lower risk
patients is likely to increase the frequency of bleeding without impacting materially on hospital associated VTE rates.

Is this guideline deliverable within the NHS?

Notwithstanding the lack of an evidence base for the recommendation, we strongly disagree with the statement within NG89 that ‘we do not expect this update to the guideline to have a significant impact on resources’ (, that is:

  1. the resource impact of implementing any single guideline recommendation will be less than £1 million per year in England (or £1800 per 100 000 population) and
  2. the resource impact of implementing the whole guideline in England will be less than £5 million per year (or £9100 per 100 000 population).

After excluding day cases and admissions lasting <24 h, we have collected census data on > 100 000 consecutive medical and surgical admissions at a large teaching hospital in England from January 2016 to June 2018 and extrapolated this to estimate some of the costs to NHS England nationally (Table 1).This estimates an additional annual cost to NHS England of over £35 million in drug costs alone, which is still over £10 million after
allowing for discounted hospital contracts. Accepting the estimate that a third of patients required a district nurse to administer the drug (Parker, 2015), this would result in an additional cost far greater than that of the drug alone (the estimated cost of a district nurse visit used for this analysis is £63), assuming there was even capacity to provide such a service. Furthermore, this does not take into account the additional nursing time required to train millions of patients and carers to administer the drug at home. Even accounting for some variation in the true figures compared to our extrapolation, implementation of this guideline clearly would have a significant impact on resources, compounded in our view by the lack of clear evidence for added benefit in outcomes.

Table 1. Estimate of annual costs in England when applying the NG89 7‐day rule.

NICE guidelines were established to provide evidence‐based recommendations and, in fact, NICE state that ‘health and social care professionals are actively encouraged to follow our recommendations to help them deliver the highest quality care (but) our recommendations are not intended to replace the professional expertise and clinical judgement of health professionals’ (

Although NICE guidelines and recommendations are not in themselves legally binding, there is the risk of this occurring through case law, e.g. Elizabeth Rose v Thanet Clinical Commissioning Group in 2014 (

In summary, the British Society for Haematology is dismayed by the current NICE guidance on thromboprophylaxis. Given the absence of evidence of benefit and estimated significant cost of full implementation of this part of NG89, we suggest that NICE review their recommendation. Currently there is a lack of will to implement these guidelines among the Haematology community (McQuaid et al, 2019), who provide much of the drive and expertise in delivering thromboprophylaxis and we are unaware of any hospital in England and Wales following this recommendation.

Conflicts of interest

WL and ML have received speaker fees from Sanofi Aventis and Leo.

Article [Wiley Online Library]

Leave a comment: