Difficult asthma

Most patients with asthma are easily diagnosed and respond to standard treatment with a short-acting inhaled β2agonist for symptom control and long-term treatment with an inhaled corticosteroid in doses of up to 2,000 μg daily. Approximately 5% of patients do not respond to this regime and require further investigation to establish the reasons for the lack of response. "Difficult asthma" may be defined as failure to achieve control when maximally recommended doses of inhaled therapy are prescribed. Although difficult asthma is usually severe, as judged by the need for extensive treatment, it may not necessarily be so as some patients have severe exacerbations but are well controlled most of the time. There are several factors that may contribute to a poor response to conventional therapy. It is important to consider these reasons systematically (table 1). Many patients with severe asthma are undertreated; in a recent survey, over 60% of patients classified as having severe asthma were not even treated with anti-inflammatory therapy [1]. All patients classified as suffering from difficult asthma should be assessed by a respiratory specialist, preferably in a specialist clinic devoted to patients with difficult asthma. Since patients with difficult asthma account for a large proportion of the direct and indirect costs of asthma, referral is financially as well as clinically justifiable [2].