Clinical Review Extracts from “Clinical Evidence”

Chronic asthma

BMJ 2001; 323 doi: (Published 27 October 2001) Cite this as: BMJ 2001;323:976
  1. Christopher Cates, general practitioner (
  1. Manor View Practice, Bushey, Hertfordshire WD2 2NN


    Definition Asthma is characterised by dyspnoea, cough, chest tightness, wheezing, variable airflow obstruction, and airway hyper-responsiveness. The diurnal variation of peak expiratory flow rate is increased in people with asthma. Chronic asthma is defined here as asthma requiring maintenance treatment. Asthma is classified differently in the United States and United Kingdom (box): where necessary, the text specifies the system of classification used. 1 2 Acute asthma is defined here as an exacerbation of underlying asthma requiring urgent or emergency treatment, and will be dealt with in a separate “Extract from Clinical Evidence.”3



    • Inhaled short acting β2 agonists as needed for symptom relief

    • Low dose, inhaled corticosteroids in mild persistent asthma

    • Adding inhaled long acting β2 agonists to inhaled corticosteroids in poorly controlled asthma (for symptom control)

    Likely to be beneficial:

    • Leukotriene antagonists for people with mild to moderate persistent asthma

    Ineffective or harmful:

    • Regular use of β2 agonists in mild intermittent asthma

    Classification of severity for chronic asthma

    United States

    Asthma is classified by symptoms of severity. Even people with mild intermittent asthma can develop severe exacerbations if exposed to appropriate stimuli.

    Mild intermittent asthma—symptoms less than weekly with normal or near normal lung function

    Mild persistent asthma—symptoms more than weekly but less than daily with normal or near normal lung function

    Moderate persistent asthma—daily symptoms with mild to moderate variable airflow obstruction

    Severe asthma—daily symptoms and frequent night symptoms, and moderate to severe variable airflow obstruction

    United Kingdom

    Chronic asthma in ambulatory settings is graded according to the amount of medication required to keep symptoms controlled. People are classified stepwise according to the drugs they need for symptom control.

    Step 1—occasional β agonists for relief of symptoms

    Step 2—in addition, regular, inhaled anti-inflammatory agents (such as inhaled corticosteroids, cromoglycate, or nedocromil)

    Step 3—in addition, high dose …

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