Evidence-Based Medicine for Student Health Services
Robert J. Flaherty, MD
Swingle Student Health Service
Montana State University
Bozeman, MT 59717
Asthma
En Espanol: http://members.es.tripod.de/asma/Flaherty5.htm
 
Etiology Monitoring
Epidemiology Prognosis
Diagnosis Prevention
Treatment Patient Education
General Information

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Etiology

Epidemiology
No evidence is cited. 

Diagnosis
Clinical Diagnosis
Of patients presenting with chronic cough, 92% had gastroesophageal reflux disease (GERD), postnasal drip syndrome, and/or asthma. Considering only patients with cough of at least 3 weeks duration who are non-smokers, are not receiving angiotensin-converting enzyme (ACE) inhibitors, and have normal or nearly normal and stable chest radiographs, 99.4% will have GERD, postnasal drip syndrome, and/or asthma. Only 39% had a single cause of cough. Laboratory/X-ray Diagnosis
No evidence is cited. 

Treatment
General Guidelines
Guidelines for the general management of asthma have been developed by the Northern & Yorkshire (UK) Research & Development Directorate:
  • Drug treatment: check compliance particularly if control is poor or treatment to be increased; check inhaler technique
  • Oral treatment should be considered as second line therapy to inhaled treatment
  • Delivery devices: use the cheapest device the patient can use and comply with effectively
  • Suggested sequence: Use a metered dose inhaler, add a large volume spacer, use a dry powder or automatic aerosol inhaler
  • For uncontrolled asthma treat with prednisolone 30-40mg daily until symptoms settle and PEFR normal
  • Treat with a short acting inhaled beta2 agonist via a nebuliser or a large volume spacer
  • Lifestyle/education: establish smoking status, advise smokers to stop, offer education about condition and its management
  • Refer to chest physician patients in whom the diagnosis is in doubt, patients with possible occupational asthma, patients who present problems in their management
(These are evidence-based guidelines.)
  • Caveats
    • Age group targeted: Adults (>18y)
    • Type/size: Practice guideline (70+ references)
    • Population characteristics: Primary care patients with asthma
    • Outcome measures: Patients having the least possible symptoms, the least possible need for bronchodilators, least possible limitation of activity,  least possible circadian variation in peak flow, best peak flow possible, least possible adverse effects from medicine
    • Date: 1996 and 1997
  • Citations
Guidelines for the emergency management of asthma from the  Canadian Association of Emergency Physicians, the Canadian Thoracic Society and the Association des médecins d'urgence du Québec:
  • Beta2-agonists are the first-line therapy for the management of acute asthma in the emergency department (grade A recommendation). 
  • Bronchodilators should be administered by the inhaled route and titrated using objective and clinical measures of airflow limitation (grade A). 
  • Metered-dose inhalers are preferred to wet nebulizers, and a
  • chamber (spacer device) is recommended for severe asthma (grade A). 
  • Anticholinergic therapy should be added to beta2-agonist therapy in severe and life-threatening cases and may be considered in cases of mild to moderate asthma (grade A).
  • Aminophylline is not recommended for use in the first 4 hours of therapy (grade A). 
  • Ketamine and succinylcholine are recommended for rapid sequence intubation in life-threatening cases (grade B).
  • Adrenaline (administered subcutaneously or intravenously), salbutamol (= albuterol) (administered intravenously) and anesthetics (inhaled) are recommended as alternatives to conventional therapy in unresponsive life-threatening cases (grade B). 
  • Severity of airflow limitation should be determined according to the forced expiratory volume at 1 second or the peak expiratory flow rate, or both, before and after treatment and at discharge (grade A). 
  • Consideration for discharge should be based on both spirometric test results and assessment of clinical risk factors for relapse (grade A). 
  • All patients should be considered candidates for systemic corticosteroid therapy at discharge (grade A). 
  • Those requiring corticosteroid therapy should be given 30 to 60 mg of prednisone orally (or equivalent) per day for 7 to 14 days; no tapering is required (grade A). 
  • Inhaled corticosteroids are an integral component of therapy and should be prescribed for all patients receiving oral corticosteroid therapy at discharge (grade A). 
  • Patients should be given a discharge treatment plan and clear instructions for follow-up care (grade C). 
(Grade A guidelines reflect the highest quality evidence.)
  • Caveats
    • Age group studied: Adults
    • Type/size: Meta-analysis and consensus (167 references)
    • Population characteristics: Emergency department patients with asthma
    • Outcome measures: Improvement in pulmonary function tests and clinical findings, discharge from ED vs hospitalization, relapse
    • Date: 1996
  • Citations
The use of a chart audit can improve the diagnosis and treatment, and decrease the cost of care, for asthmatic children. 
  • Caveats
    • Age group studied: Children
    • Type/size: RCT of 3000 patients
    • Population characteristics: 12 primary care practices = 12500 pediatric patients
    • Outcome measures: Practice initiated consultations, patient initiated consultations, structured asthma assessments, diagnosis of asthma, prescriptions of respiratory drugs, type and cost of prescriptions,  admissions
  • Citations
Inhaled Bronchodilator Therapy
Patients treated for acute asthma with albuterol metered dose inhaler (MDI) with expansion chamber (one puff each minute x6) repeated every 30 or 60 minutes, compared to 120 minutes, had a significant increase in FEV1. The rate of adverse effects, systemic steroid use, and hospitalization was not different among the treatment groups. Continuous standard dose albuterol (2.5mg over 2hrs) is as effective as high dose continuous albuterol (7.5mg over 2 hrs) at raising the FEV1 in adults with severe asthma, while causing less lowering of serum potassium levels. Continuous albuterol was superior to intermittent dosing in severe asthma. A metered-dose inhaler with a spacer for the administration of albuterol was an effective alternative to a nebulizer in children with acute asthma and resulted in both shorter treatment time  spent in the emergency department and fewer side effects. (Similar results also found with adults: See Citations below) Spacers for metered dose inhalers (MDIs) were tested to determine how much disodium cromoglycate, salbutamol (albuterol) and budesonide were delivered with each spacer as compared to the amount delivered by the MDI alone. The differences between spacers were significant for disodium cromoglycate and salbutamol (albuterol), but less significant for  budesonide. Listed in order of effectiveness: Fisonair, Nebuhaler, Volumatic, Inspirease, Aerochamber, Aerosol Cloud Enhancer and Dynahaler. The addition of a single inhalation of anticholinergics (such as ipratropium bromide) to a beta2-agonist regimen may improve lung function in children and adults with acute exacerbations of asthma treated in the emergency department. Multiple-dose anticholinergics improve lung function and may avoid hospitalisation in severe exacerbations. Other Bronchodilators
Currently available data do not indicate a significant beneficial effect of theophylline in children hospitalized with acute asthma. There is evidence for weak detrimental effects. 
  • Caveats
    • Age group studied: 1.5 - 18 y
    • Type/size: Meta-analysis (6 studies = 164 patients)
    • Population characteristics: Patients hospitalized with asthma
    • Outcome measures: Pulmonary function, changes in clinical scores, respiratory and pulse rates, length of hospital stay, need for albuterol nebulisations
  • Citations
Caffeine (5mg/kg per dose = 2-3 7oz cups of brewed coffee or 6-8 12oz cans of cola for a 70 kg adult, or more) improves airway function by a modest amount in asthmatic patients for up to four hours. Corticosteroid/Other Immune Modulator Therapy
A short course of corticosteroids following assessment for an acute exacerbation of asthma significantly reduces the number of relapses to additional care and decreases beta-agonist use without an apparent increase in side effects. Intramuscular corticosteroids appear as effective as oral agents.  Use of inhaled corticosteroids in children showed improvement in symptoms, a reduction in concomitant beta-agonist use, and a reduction in the use of oral steroids. There was no evidence of adrenal suppression, reduction in height velocity or occurrence of cataracts.
  • Caveats
    • Age group studied: Children
    • Type/size: Meta-analysis (24 studies = 1087 patients)
    • Population characteristics: Asthmatics, some dependent on oral steroids
    • Outcome measures: Symptoms, concomitant drug use, lung function tests
    • Unclear what other treatments the patients were on
  • Citations
Oral and intravenous methylprednisolone (2 mg/kg single dose) were equally effective in reducing the need for hospitalization in children with moderate to severe asthma. There appears to be no case for the routine use of methotrexate in patients on long term oral steroids.
  • Caveats
    • Age group studied: Adult
    • Type/size: Meta-analysis (10 studies = 185 patients)
    • Population characteristics: Stable steroid-dependent asthmatics
    • Outcome measures: Wide range of measurements, including alterations in steroid dosage
  • Citations
Immunotherapy 
Immunotherapy had no significant effect on asthma symptom scores. Although medication use was reduced by immunotherapy during the first year of treatment, this difference was not sustained for two years. Family physicians caring for patients with asthma should appropriately utilize the broad spectrum of inhaled anti-inflammatory medications currently available. Immunotherapy should be reserved for asthmatics proven to be allergic who exhibit flares of disease in association with allergen exposure and who have not had a satisfactory response to both environmental control and medical therapy. Other Therapies
Evidence from limited clinical trials of homeopathy is generally positive, particularly for duration of obstetric delivery, for improvement of nasal symptoms from pollinosis and pain from ankle sprains, but not for asthma, sinusitis or prevention of influenza or postoperative infections.  It is not yet possible to make any recommendations to patients, their physicians or acupuncturists about the practice of acupuncture in the treatment of asthma on the basis of the data currently reported.  The current literature does not support a definite indication for the use of vitamin C in asthma and allergy.
  • Caveats
    • Age group studied: Unknown
    • Type/size: Narrative review of 24 studies (>255 patients)
    • Population characteristics: Unknown
    • Outcome measures: Scurvy, incidence of asthma, plasma ascorbic acid levels, skin sensitivity, exercise-induced bronchospasm, severity and frequency of asthma attacks, methacholine challenge, airway tone, bronchoconstriction, cellular immunity, leukocyte function, histamine bronchoprovocation, pulmonary function
  • Citations

Monitoring
There was both a 50% reduction in total incidents caused by asthma (hospitalizations, unscheduled outpatient visits, work absence, courses of antibiotics, courses of prednisolone) over one year and improved quality of life in patients using a self management program guided by peak flow measurements as compared with traditional treatment. 
Prognosis
A clinical prediction rule accurately predicts the need for hospitalization in adult patients with asthma. It uses 3 variables measured at presentation and at 30 minutes after treatment is begun: 
  • Peak expiratory flow rate (PEFR) variation over baseline at 30 minutes in L/min (> 50 = 0 points, 20-50 = 1 point, <20 points = 2 points)
  • PEFR at 30 minutes as a % of predicted (> 45% = 0 points, 35 - 45% = 1 point, <35% points = 2 points)
  • Accessory muscle use at 30 minutes defined as visible retraction of the sternocleidomastoid muscles and depression of the supraclavicular spaces (none="0" points, mild="1" point, moderate="2" points, severe retraction and depression="3" points). 
A score >= 4 predicts the need for hospitalization. Informational handouts which describe the purpose and natural history of coughs can lower the rate of return visits for lower respiratory tract symptoms.  Children hospitalized for acute asthma whose parents received a nurse-led home management education program had fewer readmissions than did children who received usual care. (Similarly for adults - See Citations below.)
Prevention
The prophylactic use of nedocromil sodium 15 - 60 minutes before exercise was effective in inhibiting significantly the severity and duration of exercise-induced bronchospasm (EIB). This benefit appeared to be greater in patients with more severe EIB. Secondhand cigarette smoke worsens symptoms in children with asthma.  Current chemical and physical methods aimed at reducing exposure to house dust mite allergens seem to be ineffective and cannot be recommended as prophylaxis for mite sensitive asthmatics. 
  • Caveats
    • Age group studied: Unknown
    • Type/size: Meta-analysis
    • Population characteristics: Unknown
    • Outcome measures: Subjective well-being, asthma symptom scores, medication usage, days of sick leave from school/work, number of unscheduled visits to a physician/hospital, pulmonary function tests, skin prick testing
  • Citations

Patient Education
The following patient education materials are consistent with the available evidence.
Rev. 9/12/01

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