Severe asthma treatment: need for characterising patients

Asthma is readily diagnosed in most cases and usually responds to inhaled corticosteroids with or without long-acting beta agonists, theophyllines, or leukotriene-receptor antagonists, adjusted stepwise according to symptoms and lung function. However, up to 40% of adult patients with asthma remain symptomatic, and up to 5% have difficult-to-control asthma despite multiple therapies. It is suggested that higher doses of inhaled steroids with long-acting beta2 agonists should be used for total control of symptoms; and anti-IgE therapy is newly licensed in the USA. However, difficult-to-control asthma is complex and multifactorial, and is often not due to severe or therapy-resistant asthma.

Last year saw encouraging reports on omalizumab (anti-IgE therapy) in severe allergic asthma, by Stephen Holgate, Jon Ayres, and their respective colleagues (Clin Exp Allergy 2004; 34: 632-38; Allergy 2004; 59: 701-08). Omalizumab reduced exacerbation rates, improved asthma symptoms and quality of life, and allowed lower doses of inhaled steroid compared with placebo. In placebo-controlled studies with anti-IgE, many patients were able to substantially reduce and even withdraw inhaled steroids in the placebo arm.

Severe asthma is often defined as persisting symptoms despite high-dose inhaled steroids. This definition is likely to include patients with various reasons for their persisting symptoms, for whom additional treatment is not always required. Before starting new therapy, it is important to systematically evaluate asthmatic patients to accurately define their disease and to identify those whose symptoms are caused by other factors, and thus avoid unnecessary medication. There might also be subgroups that have differing underlying inflammatory processes and who will respond differently to individual treatments.