These two audits have shown improvements in our local practice using NICE CG46,6
which for general surgical patients has few substantial differences from NICE CG92, published in January 2010.11
More importantly, they have demonstrated how different our compliance with ‘best practice’ appeared to be when using different sources of guidance as the gold standard (particularly in relation to stratifying patients in any greater detail than ‘at risk’ or ‘not at risk’). These observations raise questions about which gold standard to choose for auditing practice in VTE prophylaxis and about how best to deal with stratification of risk. At the outset, it should be noted that all this focuses on ‘general surgery’ as defined above in the above Methods section and not on other disciplines such as orthopaedic surgery and general medicine.
Our compliance rates in both audits were significantly higher for the NICE CG46 ‘at risk’ criteria (81% and 90%) than for the EC or local guidelines. In other words, we performed quite well in giving prophylaxis to ‘at risk’ patients but less well when judged for our use of the correct prophylaxis for specified levels of increased risk. The percentages of patients who fell into low, moderate and high risk groups differed between the different sources of guidance. Our local discussions have highlighted the fact that patients at lower risk may pose more difficult decisions in policy making than those at high risk.12
This is in part because it may be difficult to be sure which of these patients really are at risk (for example, many fit patients become mobile very rapidly after a hernia repair or scrotal surgery but some do not and this is unpredictable).
In addition, the evidence of benefit from prophylaxis for lower-risk patients is more controversial.13,14
Our local policy, developed after Audit 1, took a particularly risk-averse approach, such that only two patients (2%) were ‘low risk’. This approach was driven by the strong patient safety agenda (both in the UK and internationally) and by other pressures that led the surgeons to agree on a low threshold for using mechanical and/or pharmacological methods of prophylaxis unless there was a good reason not to do so.
In contrast to the low-risk patients, those at particularly high risk are, by and large, easily recognised. Our highest risk patients (those who ought to have been receiving high dose low-molecular-weight heparin (LMWH), most in combination with mechanical prophylaxis) had these prescribed correctly in around 90% of cases, unlike those who required only one modality and/or lower doses of heparin. Especially when patients are at very high risk, the responsible surgeon is likely to make personal judgements about prophylaxis. This is generally accepted as best practice and is implicit in the NICE CG92, which gives recommendations for broad types of prophylaxis rather than any amount of detail about precisely what type of prophylaxis to use in patients at different levels of risk.11,13
This contrasts with the other sources of guidance used in our audits and with the internationally influential guidelines from the American College of Chest Physicians.9,10
We had originally considered using the latter in Audit 1 but decided to confine the guidelines used to three in number, relevant to the UK and Europe.
Uncertainties about the use of different doses of LMWH were in part the stimulus for our audit of practice and development of local guidelines. There is evidence that higher doses are more effective in reducing VTE in general high-risk surgery patients.15–18
However, there is no good evidence that higher doses are more effective for moderate and low-risk patients, and the risk of bleeding may be increased. There are also uncertainties about the relative effectiveness of different types of mechanical prophylaxis depending on level of risk but most specialists seem to favour IPC over GCS for patients at very high risk.10
Making clear local agreements about these methods is vital because ready availability of IPC has costs and organisational consequences greater than the routine use of GCS.