A proportion of asthmatics (probably less than 1%) continue to have severe symptoms that interfere with their lives despite the treatments described (high doses of controller inhalers, antileukotrienes or theophyllines and/or oral steroid tablets). This has been termed difficult or difficult to treat asthma.
As with any illness there are many possible reasons that treatment is ineffective: these include incorrect diagnosis: i.e. symptoms are not due to asthma, not taking the prescribed treatment (generally because it was not well explained or particular fears intervened), or co-existing problems at home that prevent good control of asthma. In surveys of difficult asthma these factors account for about half of the cases seen at specialist hospitals. Only by careful and systematic investigation are these potentially treatable problems detected. In the remaining 50% of cases asthma remains problematic despite treatment with inhalers, tables and often oral steroids.
This is the group of patients most at risk from hospital admission or death from asthma and much research is focussed to find new treatments. Possible treatments that have been used include cyclosporine A, methotrexate and more recently monoclonal antibody to IgE or Xolair. Use of these treatments require specialist assessment and monitoring.
Anti-IgE therapy may be appropriate for severe asthma with frequent attacks requiring oral steroids or hospital visits. Trials suggest it could reduce exacerbation rates by 50%. It can be used for patients with allergic asthma with total IgE concentrations in the blood between 30 and 700 units per ml. Expert assessment and monitoring is required.
Detailed assessment protocols of difficult asthma have been published. These include specific questionnaires on history, blood tests, lung function, imaging (CT scans), allergy, ENT and physiotherapy assessments. In addition psychological or psychiatric assessment is often valuable. The aim of such intensive investigation is to rule out other causes for symptoms, psychosocial problems or non-concordance with treatment and to characterise different patterns of asthma. Many regional centres now have expert clinics that can provide such investigations.