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by Thomas King, M.D.
(Presented at the 1999 CAMS Annual Scientific meeting)
Epidemiology
Despite improved understanding of the pathophysiology and the availability of new medications, the prevalence and mortality for asthma are still on the rise. In the United States, about 5% of the population suffer from asthma, the more severe cases tended to be in inner city poor areas and in those with poor access to medical care.
Pathophysiology
The important advance in patho-physiology is the recognition that asthma is a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role, in particular, mast cells, eosinophils, T lymphocytes, neutrophils and epithelial cells. In susceptible individuals, this causes recurrent wheezing, breathlessness, chest tightness and cough. With increase in bronchial hyper-responsiveness to a variety of stimuli. If left untreated, airway remodeling occurs which can lead to permanent changes.
Diagnosis and Management
The NIH convened an expert panel whose latest guidelines were published in 1997. It recognized 4 components for the diagnosis and management of asthma:
1. Measures of assessment and monitoring.. This includes the documentation of episodic and at least partially reversible airflow obstruction, the exclusion of other diagnosis and periodic assessment and monitoring.
2. Control of factors contributing to asthma severity, including avoidance of inhaled allergens and irritants and environmental controls.
3. Pharmacologic therapy. Emphasizes a stepwise approach in the use of medications tailored to the severity of asthma and the need for daily long-term therapy in those with persistent asthma.(see below)
4. Education for a partnership in asthma care. Emphasizes the importance of patient education and understanding of the disorder, the action of medications and formulation of plans for management of exacerbations and assessing goals of treatment and outcomes.
The stepwise management is summarized below for classification and treatment of asthma
Step 1 - Mild Intermittent
Symptoms
• Symptoms <= 2x/wk.
• Asymptomatic and normal PEF between exacerbations.
• Exacerbations brief, varying intensity.
Pre-treatment Pulmonary Function
• FEV1 or PEF >= 80% of predicted.
Treatment Options, Long Term control
• No daily medication needed.
Quick Relief
• Short-acting bronchodilator as needed.
Step 2 - Mild Persistent
Symptoms
• Symptoms >= 2x/wk but< 1xday.
• Exacerbations may affect activity.
Pre-treatment Pulmonary Function
• FEV1 or PEF >= 80% of predicted.
• PEF variability 20-30%.
Treatment Options, Long Term control
Daily antiinflammatory therapy:
• inhaled corticosteroid (low dose) or
• inhaled cromone
alternatives (not preferred)
• Theophylline (5-15 µg/ml)
• Leukotriene modifiers
Quick Relief
• Short-acting bronchodilator (inhaled beta2-agonist), as needed.
Step 3 - Moderate Persistent
Symptoms
• Daily symptoms.
• Daily bronchodilator use.
• Exacerbation effect.
Pre-treatment Pulmonary Function
• FEV1 or PEF >= 60%<80% of predicted.
• PEF variability > 30%.
Treatment Options, Long Term control
Daily antiinflammatory therapy: inhaled corticosteroid, medium dose or low-medium dose, and long-acting beta2-agonist or theophylline or long-acting beta2-agonist.
Quick Relief
Short-acting bronchodilator (inhaled beta-2 agonist), as needed.
Step 4 - Severe Persistent
Symptoms
• Continual symptoms.
• Limited physical activity.
• Frequent Exacerbations.
Pre-treatment Pulmonary Function
• FEV1 or PEF >= 60% of predicted.
• PEF variability > 30%.
Treatment Options, Long Term control
Daily antiinflammatory therapy:
• inhaled corticosteroid (high dose) and
• long-acting inhaled beta2-agonist, theophylline or long-acting oral beta2- agonist.
• oral corticosteroids if needed (2 mg/kg/day up to 60 mg/day).
Quick Relief
Short-acting bronchodilator (inhaled beta-2 agonist), as needed.
Prevention
Primary prevention of asthma, that is, preventing asthma onset before its development in infants of atopic parents, has just begun to be studied. Newborns are randomized into 2 groups, one of which is protected from environmental allergens from birth. Preliminary data suggest a reduction in asthma prevalence but more data are needed to confirm the finding.
Secondary prevention, in the form of avoidance of allergens and irritants and immunotherapy in selected patients, should be part of the management program for all asthma sufferers.
Dr. King is Associate Professor of Medicine , Cornell University Medical College
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