Primary prevention of cardiovascular disease will always be a controversial subject – substantial numbers of patients are eligible for treatment, but the benefits can be slim and distant.
It is little wonder that the updated NICE lipid modification guidelines1 produced front page headlines in the national press.
The most dramatic new recommendation, advocating a 10% cardiovascular risk intervention threshold, opens the way to treatment and medicalisation for many millions of ‘patients’ and is worth scrutinising in more detail.
It is highly debatable whether there is any overall mortality benefit from taking statins for primary prevention at a 10% level of risk, as highlighted in a recent BMJ editorial by a Harvard research team.2
These researchers also pointed out that adverse effects are poorly collected in trials and the data are
not openly published, but sequestered by the trial funders.
Without the major selling point of a mortality benefit, the argument for lowering the risk threshold from 20% becomes less convincing and many GPs will baulk at even trying.
If the NICE consultation process is responsive, it is possible that this recommendation will not survive the final guideline release.
NICE has at least stuck with its previous advice to use a systematic strategy to identify people at increased risk of cardiovascular disease and in practice, this means we can continue to focus on those most likely to benefit – in other words, high-risk groups.
This is fortunate, because with the all-important NNT to prevent one MI or stroke being 140 people over five years, it would be a pointless exercise trying to implement a routine 10% threshold, informing patients they might not live a day longer because of the lack of any mortality benefit.
|The draft NICE guidance|
|What is new?
Many GPs will remember the ‘Framingham versus QRISK’ debate that followed publication of the original NICE lipid modification guideline in 2008, which equivocated by advocating both.
Evidence and attitudes have consolidated and NICE has now clearly recommended using the British derived and up to date QRISK2.
The traditional measure, LDL cholesterol, has been replaced with ‘non-HDL cholesterol’, on the grounds that it does not require a fasting sample and is directly measured, unlike LDL cholesterol, which can be affected by triglyceride levels and other parameters. This is a logical move.
Another major change is the move away from the ‘treat to target’ approach that has been debated over the years, largely on the grounds that clinical trials have not used targets, but employed fixed doses.
In this respect, NICE’s suggestion that fixed doses of atorvastatin are used (simvastatin is out, following emerging data on its higher rhabdomyolysis risk) will be a relief to GPs and practice nurses, who will not face the burdensome exercise of titrating the dose against an arbitrary cholesterol level.
The advice is that for primary prevention, GPs should use atorvastatin 20mg, while for secondary prevention, atorvastatin 80mg is preferred.
Statins are now recommended for patients with type 1 diabetes, with no lower age limit specified, which is surprising and evidence free, as it may be diagnosed in infancy.
Statins remain indicated for those with type 2 diabetes, where the UK Prospective Diabetes Study calculator is recommended for assessment.
Patients with chronic kidney disease (CKD) stages 1 and 2 are recommended to start statins after risk assessment, and statins are recommended for those with CKD stages 3 and 4, as they are deemed to be at sufficient risk to warrant treatment.
There has been discussion about using lifetime cardiovascular risk instead of a 10-year risk horizon.
However, lifetime risk has one key problem – nearly everyone has it.
Academics might find addressing cardiovascular disease by medicating the entire population an attractive idea, but NICE had to work within the evidence base, which is lacking for lifetime risk, and so stayed with the 10-year risk horizon, with which most people can identify.
NICE also provides guidance on drugs to avoid. Plant stanols, sterols, omega 3 fatty acids, fibrates, resins and nicotinic acid are not recommended for the prevention of cardiovascular disease, which has the effect of streamlining lipid prescribing.
Ezetimibe is not ruled out, largely because NICE’s approach prevents it from cutting across its other technology appraisal guidance, even if the evidence is known to be weak.
Management of cardiovascular risk is about much more than just treating cholesterol levels. NICE has signposted a decision aid for raised cholesterol which seems to miss the fact that risk reduction decisions happen regardless of cholesterol level; this seems a retrograde step.
Recommendations for weight control, alcohol, diet and exercise largely replicate the original guideline and at some point, consideration will need to be given to looking at these anew.
This draft guideline takes a pragmatic approach. It is likely the 10% intervention threshold will be scaled back in some way, even if it is ultimately through poor adherence by the clinical community.
GPs will find much to approve of in the guideline and its approach to measuring cholesterol and treatment with fixed doses should be well received by GPs and patients alike.
- Dr Minhas is a GP in Kent, member of the NICE lipid modification guidelines group 2008 and author of QRISK2