SIGN guidelines point to evidence

The latest guidance on cardiovascular disease addresses the question of risk assessment. By Dr Rubin Minhas

In February the Scottish Intercollegiate Guidelines Network (SIGN) released five new cardiovascular guidelines.1

This signals major changes in clinical thinking in several areas relevant to general practice and it would be wrong to believe that because you do not practise in Scotland, they are not relevant to you. Guidelines are important because of the part they play in the implementation of the quality and outcomes framework.

SIGN and NICE share many similarities. Both apply the AGREE Collaboration framework, the international standard that assures clinicians that guidelines are of high quality and not susceptible to errors, serious bias, or commercial influence.

New guidelines
The new guidelines address risk estimation and prevention of cardiovascular disease (CVD), management of stable angina, treatment of acute coronary syndrome (ACS), chronic heart failure and cardiac arrhythmias. Each chapter is available separately and patient versions of the chapters that incorporate appropriate advice have been produced.

All clinicians with an interest in CVD should take note of the approach SIGN has taken to CVD risk estimation. The new risk calculator, ASSIGN, adjusts estimated CVD risk to take account of social deprivation using the Scottish Index of Multiple Deprivation.2 This is a significant innovation. CVD mortality rates shadow social class inequalities and older risk scores based on Framingham largely fail to detect social class gradients, so this is a fundamentally important step in reducing inequity in CVD prevention and a significant public health advance.

The performance of this new tool will be watched closely by the DoH and its success in Scotland may foreshadow its implementation in England and Wales in future. Guideline recommendations will increasingly reflect issues such as deprivation and ethnicity and it is possible that these improvements may be incorporated in future NICE?guidance.

Lipid targets
SIGN has deconstructed the debate regarding lipid targets with its methodological, real world, evidence-based guidelines. For primary and secondary prevention, it has taken an
evidence-based path away from dogma that suggested clinicians pursue a single uniform designated target for both primary and secondary prevention: risk stratification is the new paradigm.

There is no target for primary prevention – patients should be commenced on a fixed dose of simvastatin 40mg but with appropriate lifestyle advice, monitoring and attention to other risk factors, in stark contrast to ‘fire and forget’ strategies, such as with low-dose OTC statins. The reasoning appears to be ‘no evidence, no target’.

For secondary prevention, SIGN cites a systematic review. This concludes that current clinical evidence does not indicate that lipid therapy should be titrated to achieve proposed LDL cholesterol targets. Unconvinced by this lack of direct clinical trial and health economic evidence, SIGN has retained the target of 5mmol/L, while recognising that this represents the minimum standard of care. Importantly, SIGN acknowledges the importance of risk stratification in managing CVD and highlights that there are some particularly high-risk patient groups who benefit more from intensive therapy, while ensuring appropriate margins for safety.

SIGN does not incorporate health economic analysis and it remains for NICE to undertake this later in the year. SIGN has also issued guidelines for angina. These are the only current national UK guidelines for the management of this condition. They encompass diagnosis, pharmacological management and revascularisation. The accompanying chapter on ACS provides clear guidance on diagnosing, risk stratifying and managing patients with ACS.

Recommendations for heart failure are addressed. These are broadly similar to the NICE guideline for chronic heart failure. An additional recommendation is made regarding the potential use of candesartan in patients with heart failure who remain symptomatic despite ACE inhibitor therapy.

The concluding annexes provide useful advice on practical issues of initiation and up-titration of therapy. A particularly valuable feature is the inclusion of information on drugs to avoid in patients with this condition.

Cardiac arrhythmias are dealt with in a single volume. The guidance covers arrhythmias arising in a variety of settings, including AF. The overall recommendations are usefully summarised on the back cover of the guideline – a feature employed to good effect on all of the volumes.

Benchmarking
These guidelines set a benchmark for validity. The clinical recommendations represent the impartial, transparent application of scientific evidence and clinical reasoning by multidisciplinary groups, while taking account of health inequalities and providing valuable information for patients.

The adoption of a risk stratification approach is concordant with contemporary thinking and permits proportionality in managing risk for higher and lower risk groups. The SIGN guidelines are highly recommended as practical and reliable tools for evidence-based clinicians.

- Dr Rubin Minhas is a GP in Gillingham, Kent, and CHD clinical lead at Medway PCT. He is a NICE?Technology Appraisal Committee member and has received honoraria from pharmaceutical companies for educational meetings and advisory panels. These are his personal views.

References
1. SIGN?guidelines on CHD and stroke. February 2007.
2. ASSIGN score

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