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*Chair of the editorial committee, Centre de pneumologie, Institut de cardiologie et de pneumologie de l'Université Laval, Hôpital Laval, Sainte-Foy, Que.; Department of Pediatrics, University of Manitoba, Winnipeg, Man.; Service de pneumologie, Hôpital Sainte-Justine, Montréal, Que.; ¶Atlantic Health Sciences Corp., Saint John, NB; Division of Clinical Epidemiology, Royal Victoria Hospital, Montréal, Que.
Abstract
Objectives: To provide physicians with current guidelines for the diagnosis and optimal management of asthma in children and adults, including pregnant women and the elderly, in office, emergency department, hospital and clinic settings.
Options: The consensus group considered the roles of education, avoidance of provocative environmental and other factors, diverse pharmacotherapies, delivery devices and emergency and in-hospital management of asthma.
Outcomes: Provision of the best control of asthma by confirmation of the diagnosis using objective measures, rapid achievement and maintenance of control and regular follow-up.
Evidence: The key diagnostic and therapeutic recommendations are based on the 1995 Canadian guidelines and a critical review of the literature by small groups before a full meeting of the consensus group. Recommendations are graded according to 5 levels of evidence. Differences of opinion were resolved by consensus following discussion.
Values: Respirologists, immunoallergists, pediatricians and emergency and family physicians gave prime consideration to the achievement and maintenance of optimal control of asthma through avoidance of environmental inciters, education of patients and the lowest effective regime of pharmacotherapy to reduce morbidity and mortality.
Benefits, harms and costs: Adherence to the guidelines should be accompanied by significant reduction in patients' symptoms, reduced morbidity and mortality, fewer emergency and hospital admissions, fewer adverse side-effects from medications, better quality of life for patients and reduced costs.
Recommendations: Recommendations are included in each section of the report. In summary, after a diagnosis of asthma is made based on clinical evaluation, including demonstration of variable airflow obstruction, and contributing factors are identified, a treatment plan is established to obtain and maintain optimal asthma control. The main components of treatment are patient education, environmental control, pharmacotherapy tailored to the individual and regular follow-up.
Validation: The recommendations were distributed to the members of the Canadian Thoracic Society Asthma and Standards Committees, as well as members of the board of the Canadian Thoracic Society. In addition, collaborating groups representing the Canadian Association of Emergency Physicians, the Canadian College of Family Physicians, the Canadian Paediatric Society and the Canadian Society of Allergy and Immunology were asked to validate the recommendations. The recommendations were discussed at regional meetings throughout Canada. They were also compared with the recommendations of other similar groups in other countries.
Dissemination and implementation: An implementation committee has established a strategy for disseminating these guidelines to physicians, other health professionals and patients and for developing tools and means that will help integrate the recommendations into current asthma care. The plan is outlined in this report.
Sponsors: This is a joint report of the Canadian Thoracic Society, the Canadian Paediatric Society, the Canadian Society of Allergy and Clinical Immunology, the Canadian Association of Emergency Physicians and the Family Physician Asthma Group of Canada. It is sponsored by these organizations, as well as the Lung Association and the College of Family Physicians of Canada. It was supported by 3M Pharmaceuticals, Astra Pharma Inc., Boehringer Ingelheim Canada, Ltd., Glaxo Wellcome Canada Inc., Merck Frosst Canada Inc., Novartis Pharma Canada Inc and Zeneca Pharma Inc.
In light of recent research, a group of respirologists, pediatricians, immunoallergists, emergency and family physicians met at Niagara-on-the-Lake, Ont., from 28 to 31 May 1998, to review and revise the 1995 recommendations.3
All recognized the importance of adapting treatment to the individual and the situation at hand; however, we provide these evidence-based recommendations as a guide to clinicians. Recommendations are made for both adults and children. There may be some duplication of information across the various sections, but this will allow a more comprehensive reading of each section and emphasize the most important messages.
Goals
The goals of participants in the conference were to:
Levels of evidence
Recommendations are based on a critical review of the scientific literature by small groups before the meeting and are categorized into 5 levels according to the strength of the supporting evidence (Table 1).4
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These 5 levels do not describe the quality or credibility of the evidence; rather, they indicate its nature. In general, a randomized, controlled trial has the greatest credibility (level I evidence); however, it may have defects that diminish its value, and these should be noted. Evidence based on too few observations to give a statistically significant result is classified as level II. Generally, level III studies carry less credibility than level I or level II studies, but credibility is increased when consistent results are obtained from several level III studies carried out at different times and in different places.
Decisions must often be made in the absence of published evidence. In these situations, it is necessary to rely on the opinion of experts based on their knowledge and clinical experience. Distinction is made between the published opinion of authorities (level IV) and the opinion of those who have contributed to these guidelines (level V). Nevertheless, because of the exhaustive consensus-building process used in the preparation of these guidelines, this level V evidence has achieved a level of credibility that is at least equivalent to level IV evidence.
General principles of management of asthma
Asthma is characterized by paroxysmal or persistent symptoms such as dyspnea, chest tightness, wheezing, sputum production and cough, associated with variable airflow limitation and a variable degree of hyperresponsiveness of airways to endogenous or exogenous stimuli.
Inflammation and its resultant effects on airway structure are considered to be the main mechanisms leading to the development and maintenance of asthma; therefore, the main thrust of asthma therapy is to limit exposure to triggering factors and to reduce the inflammatory process using anti-inflammatory agents. If needed, therapies to maintain optimal airway calibre and to control symptoms may be added to ensure acceptable asthma control and to improve quality of life. This requires individual assessment of the need for therapeutic intervention and establishment of the risks and benefits of various therapeutic choices (environmental measures, education and pharmacotherapy).
Environmental control, particularly avoidance of relevant allergens and respiratory irritants, and proper patient education are essential to achieve adequate control of asthma. A list of the most common environmental measures is included in the section on environment.
Conference participants agreed to retain the concept of the asthma continuum adopted at the last Canadian Asthma Consensus Conference,3 reflecting a dynamic therapeutic approach that allows drug therapy to be adapted to the severity of the underlying illness and facilitates adjustment of the intensity of therapy to the degree of control achieved.
They also agreed that the concept of "control" of asthma should be differentiated from "severity" of asthma.5
Criteria for asthma control
Although optimal control of asthma means the absence of respiratory symptoms and of the need for rescue bronchodilator, as well as normal pulmonary function, this is difficult to achieve in all patients with asthma. The participants preferred to base treatment needs on what they defined as acceptable asthma control, using clinical and physiologic parameters (Table 2). Such control is obtained through appropriate environmental measures, proper patient education and pharmacotherapy tailored to the individual. Control should be regularly assessed and treatment adjusted accordingly.
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Assessment of the severity of asthma
The severity of asthma in a patient is judged by the frequency and duration of respiratory symptoms, the presence of persistent airflow limitation and the medication required to maintain control. When asthma is well controlled, one of the best ways to judge severity is to determine the level of treatment needed to maintain acceptable control (see Table 3 and the section on diagnosis and evaluation).
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Signs of severe or poorly controlled asthma also include:
Each new treatment should be viewed as a therapeutic trial and its efficacy assessed by monitoring control according to the criteria described above. Furthermore, asthma severity is likely to vary over time; this is especially so in children, in whom asthma often decreases with age, and suggests the need to attempt to reduce medication when asthma ceases to be troublesome. Once control of asthma has been maintained for at least several months, an attempt should be made to reduce medication within the bounds of acceptable control.
Asthma management: a continuum
We propose the following algorithm for the management of asthma:
A. When asthma is suspected from symptoms and clinical presentation, confirm diagnosis by objective measures of variable airflow obstruction and assess severity
• Spirometry (the preferred method): A 12% (preferably 15%) or greater improvement in FEV1 (i.e., at least 180 mL) from the baseline 15 minutes after use of an inhaled short-acting ß2-agonist, a 20% (250 mL) or greater improvement after 10-14 days of ingested prednisone when symptoms are stable or 20% (250 mL) or greater "spontaneous variability" is considered significant.
• Serial measures of PEF: > 20% change after administration of a bronchodilator or over time.
• Methacholine challenge: Provocative concentration of methacholine giving a 20% reduction in FEV1 (PC20) < 8 mg/mL (Juniper method6).
B. Rapidly achieve best asthma control
• If symptoms are infrequent and expiratory flows are normal, an inhaled short-acting ß2-agonist should be used on demand.
• If a rescue ß2-agonist is needed more than 3 times a week or if lung function is abnormal, an inhaled glucocorticosteroid equivalent to 400-1000 µg/d of beclomethasone dipropionate is the preferred next step (200-1000 µg/d in children).
• If symptoms are frequent and expiratory flows are < 60% of predicted value, initial therapy with prednisone should be considered.
C. Maintain acceptable asthma control (Table 2 and Fig. 1)
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• Determine minimal medication needs to keep best results, then write an action plan (Appendix).
D. Ensure regular follow-up
• Regularly review asthma control, medication needs and the action plan.
• Reassess environmental control and compliance with treatment.
• Assess the need for additional investigation, education or referral.
General principles of drug therapy
Medications used to treat asthma are generally divided into 2 main categories: relievers and controllers.
Relievers are best represented by the inhaled short-acting ß2-agonists. These quick-acting bronchodilators are used to relieve acute intercurrent asthma symptoms, only on demand and at the minimum required dose and frequency. Inhaled ipratropium bromide is less effective, but is occasionally used as a reliever medication in patients intolerant of short-acting ß2-agonists.
Controllers (or preventers) include anti-inflammatory medications, such as inhaled (and oral) glucocorticosteroids, leukotriene-receptor antagonists, and anti-allergic or inhaled nonsteroidal agents, such as cromoglycate and nedocromil. These agents are generally taken regularly to control asthma and prevent exacerbations. Inhaled glucocorticosteroids are the most effective agents in this category.
The controller group also includes some bronchodilators that are taken regularly in addition to inhaled glucocorticosteroids to help achieve and maintain asthma control. These include the long-acting inhaled ß2-agonists salmeterol and formoterol, which are the first choice in this category, as well as theophylline and ipratropium. The ß2-agonists and ipratropium are considered of no significant benefit in reducing airway inflammation. There is some evidence that theophylline may have immunomodulatory effects, but the clinical significance of this remains to be demonstrated.
Asthma drugs are preferably inhaled, because this route minimizes systemic absorption and, thus, improves the ratio of the therapeutic benefit to the potential side-effects. The patient must have repeated instruction on how to use the inhaled medication. The recently developed oral leukotriene-receptor antagonists have good safety and tolerance profiles and are taken orally, which may help certain patients comply with treatment.
Asthma medications should be used at the minimum dose and frequency required to maintain acceptable asthma control; they should not be used as a substitute for proper control of the environment. Asthma medications are considered to be safe over many years when used appropriately.
The participants in the asthma consensus conference have reviewed the role of each category of medication. In the following sections they describe briefly the mode of action, pharmacologic and clinical profile, mode of administration and potential side-effects of these drugs.
Competing interests: The authors have received consultancy fees, travel assistance to attend meetings, speaker fees and honoraria from various manufacturers of asthma medications.
Sponsoring organizations: The Canadian Association of Emergency Physicians; Canadian Pediatric Society; The Canadian Society of Allergy and Clinical Immunology; Canadian Thoracic Society; College of Family Physicians of Canada; Family Physician Asthma Group of Canada; The Lung Association
Supporters: The Lung Association; 3M Pharmaceuticals; Astra Pharma Inc.; Boehringer Ingelheim Canada, Ltd.; Glaxo Wellcome Canada Inc.; Merck Frosst Canada Inc.; Novartis Pharma Canada Inc; Zeneca Pharma Inc.
Footnotes
This article has been peer reviewed.
Correspondence and reprint requests to: Dr. Louis-Philippe Boulet, Hôpital Laval, 2725, chemin Sainte-Foy, Sainte-Foy QC G1V 4G5; tel 418 656-4747; fax 418 656-4762; lpboulet@med.ulaval.ca
Appendix 1-1
Members of the Canadian Asthma Consensus Group: John C. Acres, MD, Moncton, NB; Tony R. Bai, MD, Vancouver, BC; Meyer S. Balter, MD, Toronto, Ont.; Allan Becker, MD, Winnipeg, Man.; Denis Berubé, MD, Montréal, Que.; Robert Beveridge, MD, Saint John, NB; Jacques Bouchard, MD, La Malbaie, Que.; Louis-Philippe Boulet, MD, Sainte-Foy, Que.; Dennis M. Bowie, MD, Halifax, NS; William W. Busse, MD, Madison, Wisc.; André Cartier, MD, Montréal, Que.; Andrew J. Cave, MD, Edmonton, Alta.; Moira Chan-Yeung, MD, Vancouver, BC; Kenneth R. Chapman, MD, Toronto, Ont.; Victor Chernick, MD, Winnipeg, Man.; Donald W. Cockcroft, MD, Saskatoon, Sask.; Johanne Côté, MD, Sainte-Foy, Que.; Robert L. Cowie, MD, Calgary, Alta.; Anna Day, MD, Toronto, Ont.; Mervyn M. Dean, MD, Corner Brook, Nfld.; Myrna Dolovich, PEng, Hamilton, Ont.; Denis Drouin, MD, Québec, Que.; Francine Ducharme, MD, Montréal, Que.; Nigel J. Duiguid, MD, St. John's, Nfld.; Anthony D. D'Urzo, MD, Toronto, Ont.; Gordon H. Dyck, MD, Steinback, Man.; Pierre Ernst, MD, Montréal, Que.; Alexander C. Ferguson, MD, Vancouver, BC; J. Mark Fitzgerald, MD, Vancouver, BC; Anton F. Grunfeld, MD, Vancouver, BC; Frederick E. Hargreave, MD, Hamilton, Ont.; Richard V. Hodder, MD, Ottawa, Ont.; John Hoey, MD, Ottawa, Ont.; Daniel Hughes, MD, Halifax, NS; Robert H. Hyland, MD, Toronto, Ont.; Robert Jin, MD, Ottawa, Ont.; Alan Kaplan, MD, Richmond Hill, Ont.; John Kolbe, MD, Auckland, NZ; Thomas Kovesi, MD, Ottawa, Ont.; Brent L. Kvern, MD, Winnipeg, Man.; Eric S. Leith, MD, Oakville, Ont.; Alex Leung, MD, Kamloops, BC; Ian B. MacLusky, MD, Toronto, Ont.; Carina M. Majaesic, MD, Edmonton, Alta.; S.F. Paul Man, MD, Edmonton, Alta.; Francisco J.D. Noya, MD, Montréal, Que.; Paul O'Byrne, MB, Hamilton, Ont.; J. Grahame Owen, MD, Oakville, Ont.; Sharon D. Peters, MD, St. John's, Nfld.; Georges B. Rivard, MD, Sainte-Foy, Que.; Michel-Y. Rouleau, MD, Québec, Que.; Robert Schellenberg, MD, Vancouver, BC; Malcolm R. Sears, MB, Hamilton, Ont.; Estelle R. Simons, MD, Winnipeg, Man.; Arthur Slutsky, MD, Toronto, Ont.; Sheldon Spier, MD, Calgary, Alta.; Robert L. Thivierge, MD, Montréal, Que.; John H. Toogood, MD, London, Ont.; Michel Turgeon, MD, Sainte-Foy, Que.; David W. Warren, MD, London, Ont.; Sally E. Wenzel, MD, Denver, Colo.; Barry Zimmerman, MD, Toronto, Ont.
References
This article has been cited by other articles:
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 S Suissa, P Ernst, and A Kezouh Regular use of inhaled corticosteroids and the long term prevention of hospitalisation for asthma Thorax, October 1, 2002; 57(10): 880 - 884. [Abstract] [Full Text] [PDF]
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 A. J. Bonnin, V. A. Marinkovich, M. Romagnoli, L. M. Fabbri, E. T. Naureckas, and J. Solway Mild Asthma N. Engl. J. Med., April 25, 2002; 346(17): 1335 - 1336. [Full Text] [PDF]
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