The aim of this guideline is to provide recommendations, evidence based where possible, to guide primary health care professionals in their management of adult patients with asthma. The development group assumes that health care professionals will use general medical knowledge and clinical judgement in applying the general principles and specific recommendations of this document to the management of individual patients. Recommendations may not be appropriate for use in all circumstances. Decisions to adopt any particular recommendation must be made by the practitioner in the light of available resources.
Responsibility and support for guideline
development
The guideline development group was composed of three broad groups: relevant health care professionals and patients; an a specialist resource and a specialist small group leader; and members of the research team.
It was important that the group contained individuals from appropriate sectors (Russell et al., 1993); the sectors approached were general practitioners, practice nurses, patient groups, secondary care physicians and public health physicians. These group members were there to ensure adequate relevant discussion of the evidence, of areas where there was no evidence and the subsequent recommendations in the guideline.
The specialist resource was a chest physician. He worked closely with the research team, discussing the literature search strategy, reviewing and summarising the literature and feeding this information back to the group. The small group leader had the role of ensuring that the group worked effectively. The research team was responsible for the pursuit of the group task, undertaken by the principal investigator, and the resourcing of the group.
The development group membership was (in alphabetical order):
Dr James Anderson, General Practitioner, Durham
Dr Steve Bourke, Consultant Chest Physician, Newcastle upon Tyne
Dr Bill Cunningham, General Practitioner, Corbridge (Small group leader)
Dr Martin Eccles, Health Services Researcher, Centre for Health Services Research (Guideline development leader)
Dr Bernard Higgins, Consultant Chest Physician, Newcastle upon Tyne (Specialist resource)
Prof Sean Hilton, Dept of General Practice and Primary Care, St George's Hospital Medical School, London
Dr David Jeavons, General Practitioner, Darlington
Mrs Margaret Jenkyns, Patient, Newcastle upon Tyne
Dr Kevin Jones, Dept of Primary Health Care, University of Newcastle upon Tyne
Kim Mansfield, Respiratory Nurse Specialist, North Shields
Sister Allana Massingham, Practice Nurse, Darlington
Mr Paul McNamee, Health Economist, Morpeth
Dr Paula Whitty, Consultant, Public Health Medicine, South Tyneside.
Meetings took place during a weekday afternoon. This arrangement ensured that meetings were long enough (3• hours) to ensure sufficient
time for the task, but also that they would be held at a time of day when group members had not already completed a full day's work. All group members were offered reimbursement of their travelling expenses, and general practitioners and practice nurses were offered reimbursement for any locum expenses incurred. As the skills provided by the small group leader and the specialist resource were central to the functioning of the group they were paid a fee in recognition of their work. A light sandwich lunch was available before the meeting for those who wanted it.
Evidence identification, review and synthesis
The search strategy was carried out using the electronic database MEDLINE and covered the period January 1985 to August 1994 (Appendix 1). This ten year period was a pragmatic decision influenced by the volume of papers and the time and resources available. All the searches carried out were limited to "english language", human studies and to the age bands of 18 years and above using the MEDLINE options. Certain types of study were of more relevance to our purpose than others and so we conducted MeSH heading and free text searches using the terms: meta analysis; randomised controlled trials; reviews; cohort studies or case control studies. This also linked in with our need to grade levels of evidence (Sackett, 1986). The method of restricting the literature by limiting the search to mainstream journals (Sackett et al., 1991) was considered, but was rejected for two reasons: firstly it did not reduce the number of irrelevant documents substantially and resulted in rejecting papers on areas such as management of care which were already limited in number; and secondly because of the breadth of the subject the number of mainstream journals was still large. Additional MEDLINE searches were carried out in the following specific areas: decision making; theophylline; terbutaline; antihistamine.
In addition to the main MEDLINE search, references were identified from three other sources. The BIDS on-line database was searched (using the search strategy "asthma + management"). If there was no recent evidence in a clinically important area the specialist resource was asked to identify, from his personal knowledge, key articles published before 1985, the lower time limit of our electronic search. Also, although non-systematic reviews
were not used for our evidence review, their reference lists were checked to ensure that we had identified relevant articles cited by them. Relevant articles published pre-1985 were also identified in this way (e.g. British Thoracic and Tuberculosis Association, 1975, 1976). We did not attempt to access the grey literature (unpublished reports and abstracts), nor did we identify letters in response to original articles.
| Table 1: Number of MEDLINE references remaining at various stages of the sifting process | |
| Stage of the sifting process | 1985-1994 |
| All refs | 27401 |
| Restricted to English only | 19005 |
| Restricted to human and adult only | 18189 |
| Restricted by publication type | 4936 |
| Sifted on title (HSR) | 1034 |
| Sifted on abstract (consultant) | 513 |
| Methodological sift - accepted | 150 |
| Methodological sift - rejected | 331 |
| Not used | 32 |
The total number of references identified was 802: 522 from MEDLINE (this includes nine outside 1985-94 limit), 49 from BIDS, 80 from the specialist resource, and 153 from the citations of non-systematic reviews.
Due to the volume of literature, the reviewing task was extended beyond the single expert reviewer by taking discrete areas of the literature and inviting group members to review these on behalf of the group. Reviewers were provided with explicit written instructions to guide them in order to ensure consistency (Appendix 3). The number of papers rejected at this stage and the reason for rejection are shown in Table 2.
| Table 2: Methodological criteria for rejecting papers | ||
| Reason for rejecting article | Number rejected | % of total sifted (672* papers) |
| Less than 80% follow-up | 47 | 7 |
| Group sizes smaller than 20 | 238 | 35 |
| No control group | 25 | 4 |
| No method section (reviews) | 65 | 10 |
| Other design flaws | 37 | 6 |
| Other e.g. length of follow-up, population poorly sampled, etc | 37 | 6 |
| Total rejected on methodology | 453 | 67 |
| * 672 papers were identified as relevant to the task - a further 130 had been collected, but were not used because the areas were covered by good meta-analyses or because, after group discussion, the areas were felt to be outside the scope of the guideline. | ||
Of the 672 papers 226 were accepted after the methodological sift. Certain methodological criteria were not regarded as absolute methodological flaws but were of sufficient importance to merit mention in the text. The commonest of these was an experimental study at risk of a Type II error. This means that the study had a negative result (it concluded there was no difference between groups) but it did not provide any evidence that the study had sufficient power to detect a difference were one there. This is referred to in the guideline as either "at risk of a Type II error" or "a negative study without a power calculation".
I:based on well-designed randomised controlled trials, meta-analyses or systematic reviews
II:based on well-designed cohort or case control studies
III: based on uncontrolled studies or consensus.
External review of the guideline
The following external reviewers sent comments on the guideline:
Dr S Conway, General Practitioner, Hingham, Norfolk
Dr A Farmer, General Practitioner, Thame, Oxfordshire
Dr G Feder, Senior Lecturer, Academic Department of General Practice and Primary Care, Medical Colleges of St Bartholomew's and The London Hospitals
Dr JAR Friend, Consultant in Thoracic Medicine, Aberdeen Royal Infirmary, Aberdeen
Dr BDW Harrison, Consultant Physician, West Norwich Hospital, Norwich
Dr PW Jones, Reader in Medicine, St George's Hospital Medical School, London
Dr MR Partridge, Consultant Chest Physician, Whipps Cross Hospital, Leytonstone, London.
Their comments influenced the style and content of the guideline; however, the guideline remains the responsibility of the development group.
Piloting/pre-testing
of the guideline
The guideline will be pre-tested as part of its further validation. This will be done within the Royal College of General Practitioners' appraisal system.
Scheduled review of the
guideline
The guideline should be reviewed no later than three years after its completion. This will be done within the Northern and Yorkshire Region's guideline development structure.
with oral prednisone in patients starting long-term corticosteroid therapy for asthma. Lancet 469-473.
British Thoracic and Tuberculosis Association (1976) A controlled trial of inhaled corticosteroids in patients receiving prednisone tablets for asthma. British Journal of Diseases of the Chest 70:95-103.
British Thoracic Society, British Paediatric Association, Royal College of Physicians, King's Fund Centre, National Asthma Campaign, Royal College of General Practitioners, General Practitioners in Asthma Group, British Association of Accident and Emergency Medicine, and British Paediatric Respiratory Group (1993) Guidelines on the management of asthma. Thorax 48:s1-s24.
Canadian Task Force (1979) Canadian Medical Association Journal 121:1193-1254.
Guyatt, G.H., Sackett, D.L. and Cook, D.J. (1994) Users' guides to the medical literature II How to use an article about therapy or prevention. B. What were the results and will they help me in caring for my patients? Journal of the American Medical Association 271:59-63.
Jaeschke, R., Guyatt, G. and Sackett, D.L. (1994a) Users' guide to the medical literature. III: How to use an article about diagnostic test. A. Are the results of the study valid? Journal of the American Medical Association 271:389-391.
Jaeschke, R., Guyatt, G.H. and Sackett, D.L. (1994b) Users' guide to the medical literature. III: How to use an article about a diagnostic test. B. What are the results and will they help me in caring for my patients? Journal of the American Medical Association 271:703-705.
Kleijnen, J., Knipschild, P. and ter Riet, G. (1991a) Clinical trials of homoeopathy. British Medical Journal 302:316-323.
Kleijnen, J., ter Riet, G. and Knipschild, P. (1991b) Acupuncture and asthma: a review of controlled trials. Thorax 46:799-802.
Koes, B.W., Bouter, L.M., Beckerman, H., van der Heijden, G.J.M.G. and Knipschild, P.G. (1991) Physiotherapy exercises and back pain: a blinded review. British Medical Journal 302:1572-1576.
Russell, I., Grimshaw, J. and Wilson, B. (1993) Scientific and methodological issues in quality assurance. Proceedings of the Royal Society of Edinburgh 101B:77-103.
Sackett, D.L. (1986) Rules of evidence and clinical recommendations on the use of antithrombotic agents. Chest 89(2):2S-3S.
Sackett, D.L., Haynes, R.B., Guyatt, G.H. and Tugwell, P. (1991) Surveying the medical literature to keep up to date. In: Clinical epidemiology: a basic science for clinical medicine. London: Little, Brown & Company, p. 359-378.
ter Riet, G., Kleijnen, J. and Knipschild, P. (1990a) Acupuncture and chronic pain: a criteria based meta-analysis. Journal of Clinical Epidemiology 43:1191-1199.
ter Riet, G., Kleijnen, J. and Knipschild, P. (1990b) A meta-analysis of studies into the effect of acupuncture on addiction. British Journal of General Practice 40:379-382.
West, R. (1992) Assessment of evidence versus consensus or prejudice. Journal of Epidemiology and Community Health 46:321-322.