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The new BTS/SIGN asthma guidelines: where evidence leads the way
  1. B G Higgins1,
  2. J G Douglas2
  1. 1Freeman Hospital, Newcastle upon Tyne, UK
  2. 2Aberdeen Royal Infirmary, Aberdeen, UK
  1. Correspondence to:
    Dr B G Higgins, Freeman Hospital, High Heaton, Newcastle upon Tyne NE7 7DN, UK; b.g.higgins{at}ncl.ac.uk

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Announcing the publication of the new BTS/SIGN asthma guidelines as a supplement to this issue of Thorax.

It is 12 years since the first British guidelines on asthma management in adults were published as two papers in the BMJ.1,2 The British Thoracic Society (BTS) guidelines were rewritten in 19933 with additional advice on childhood asthma, and further updated in 1995.4 Elsewhere, the Scottish Intercollegiate Guidelines Network (SIGN) published their guideline on the hospital management of asthma in 19965 based on the BTS work, and subsequently published on the primary care management of asthma in 19986 and the management of acute asthma in 1999.7 While the BTS versions have been among the most widely implemented of all clinical guidelines, there has been an increasing need to update them using evidence-based methodology and covering all aspects of asthma care. With this issue of Thorax the new British guidelines on the management of asthma8 produced jointly by the BTS and SIGN are published in a separate supplement. The development process has involved individuals from all relevant professional groups involved in asthma care in the UK. Initial literature searches based on key questions produced over 15 000 abstracts and all relevant published papers up to the end of September 2001 were considered. What changes has this evidence-based review brought?

For those familiar with the previous guideline, the striking features will be the change in style and the increased size of the new version. The design will be more familiar to those working in Scotland since it follows the basic pattern of all SIGN publications. It is important—and hopefully interesting—for readers to be able to link the recommendations in the guideline to the supporting evidence, and the format of the guidelines follows naturally from this. Explanatory paragraphs citing the available evidence are accompanied by a clear recommendation. Although these are graded, it is worth emphasising that this reflects the strength of the evidence and not necessarily the importance of the recommendation. Those daunted by the size of the document will find that the recommendations are clearly highlighted, and anyone with a mind to do so will easily be able to pick their way through these and leave the supporting text for another day.

The guideline has grown bigger because several topics are covered in greater detail than previously and some new areas are included. There is a section addressing treatment of asthma by non-pharmacological methods including complementary medicine, acupuncture, homeopathy, and immunotherapy. This is an area of immense interest to many patients and a common reason for consultation with the UK National Asthma Campaign helpline; those practising more orthodox medicine need to be able to offer some guidance when patients ask advice about alternative treatments. There are also expanded sections on diagnosis and on the management of asthma in pregnancy. Some readers will feel that these contain nothing new, but there is still great concern about misdiagnosis of asthma, particularly in children, and evidence that patients with asthma tend to be undertreated when pregnant, indicating a need for guidance in these areas. The large bodies of literature on self-management of asthma and organisation of care have also been explored and have led to some strong recommendations to implement measures which may not be current standard practice everywhere. Advice on the performance of high quality audit of asthma care is also included for the first time.

What key messages does the guideline offer and what has changed from the previous version? For many the nucleus of the guideline will be the advice on pharmacological management, particularly the treatment steps, and the section on management of acute asthma. The steps have been retained and there are still five in adults and older children (although consideration of step 3 suggests that this may be difficult to retain in future). There are, however, changes in the sequencing of treatment with a new emphasis in adults—and most particularly in children—on trials of other treatment before a patient reaches higher doses of inhaled steroid. This stems firstly from the evidence which shows that, although an inhaled steroid is the first choice preventative treatment in asthma, high doses are infrequently required; secondly, from concerns regarding the potential dangers of high doses, especially in children; and finally from the strong evidence of benefit from the introduction of long acting β agonists at step 3. The ceiling dose of inhaled steroid at step 3 has therefore been brought down to 800 μg beclomethasone or equivalent in adults (compared with 2000 μg in the previous BTS guideline) and 400 μg in children. It is recommended that other agents, specifically a long acting β agonist in the first instance, should be tried before exceeding these doses. For the management of acute asthma the eye catching changes are the inclusion of advice on intravenous magnesium as a treatment option for severe non-responding or life threatening attacks and the potential use of continuous nebulisation of β agonists. No less important is the advice on identification of those patients at risk of life threatening asthma attacks.

Although these sections of the guideline are rightly regarded as important, it is to be hoped that the other sections are not dismissed as being of lesser value. Most paediatricians will tell cautionary tales of children in whom other diagnoses have been missed while the patient’s asthma medication was remorselessly increased. Adult physicians too will recognise this scenario, hence the encouragement to seek objective support for the diagnosis of asthma and to review this when the response to treatment is poor. Similarly, many patients with asthma still do not have an agreed Asthma Action Plan (formerly known as a self-management plan), yet there is good evidence that doing so is of clinical benefit in terms of overall morbidity and in avoiding the need for hospitalisation. Action plans are best introduced as part of a structured educational package and practices which do not offer these should be encouraged to do so, particularly targeting patients whose treatment is at steps 3–5 and those who have had a recent hospital admission or A&E attendance. The literature on inhaler devices has also been reviewed. Metered dose inhalers, with or without spacers, have been shown to be as effective as other devices but, as ever, the pragmatic advice is to match the device to the patient on the basis of individual technique and preference.

At face value the section on non-pharmacological management offers no compelling reason for change from conventional practice. There is disappointingly little evidence of efficacy even for measures which many have long felt should be beneficial, such as reduction of exposure to house dust mite or avoidance of pet allergen. However, those reviewing this literature will feel that what is necessary is more conclusive evidence, be it positive or negative. This also applies to the data on alternative medical therapies where high quality studies are few. Even where there is good evidence of efficacy, recommendations are not necessarily clear cut. Immunotherapy can improve asthma but there are insufficient data to assess its value relative to conventional pharmacological treatment.

These are issues which require further research and, indeed, this is one of the great secondary benefits of producing formal evidence-based guidelines. The extensive review of the literature which is part of the process has revealed many areas where more evidence is needed before clear guidance can be given. The gaps in our knowledge are sometimes surprising. For example, despite the number of pharmacological studies carried out in asthma, we still do not know the threshold at which inhaled steroids should be introduced and we have no evidence to help decide which treatment strategy to try first at step 4. Some will regard it as a failure that there are not more grade A recommendations, but it would be better to regard this as a challenge. We have the opportunity to take this as a starting point from which to analyse the major gaps in our knowledge and develop appropriate research to address these. This process has already started with an initiative led by the Asthma Taskforce, administered by the National Asthma Campaign.

A further consideration for the future is the concept of developing a “living guideline”. This would involve a regular—probably annual—review of the literature and revision of the guideline where appropriate. It is extremely difficult to keep a guideline both up to date and yet also grounded on firmly established evidence, but the current system of major revision every few years may lean too far away from the former aim.

In the meantime we believe that this new joint BTS/SIGN guideline represents the best synthesis of available evidence and practical advice on the clinical management of asthma. Implementing the recommendations should lead to improved care for our patients but, in addition, we would be delighted if this guideline acted as a stimulus to improving the evidence base available in the future.

Announcing the publication of the new BTS/SIGN asthma guidelines as a supplement to this issue of Thorax.

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