Clinical asthma phenotypes in the real world: opportunities and challenges

Abstract

Asthma is a common, chronic and heterogeneous syndrome, affecting people of all ages, all races and both sexes. It may range from mild disease with barely noticeable symptoms, to very severe disease with constant symptoms that greatly hinder the life of the patient. Guidelines issued by various medical societies provide guidance on how to diagnose and manage asthmatic patients. It is now increasingly recognised that asthma management must be individualised, tailored not only to the severity of the disease but to the phenotypic characteristics of each patient. The aim of asthma treatment is control of asthma and the prevention of risk of exacerbations and fixed airflow limitation. Asthma control can be easily assessed clinically through simple screening tools such as the use of validated questionnaires and spirometry. The use of inflammatory biomarkers can be an alternative approach that, however, requires more time and resources. Asthma treatment involves the use of controllers, mainly inhaled corticosteroids and long-acting β2-agonists, and relievers, mainly rapid-acting β2-agonists. Controller medications reduce airway inflammation, lead to better symptom control and reduce the risk of future exacerbations. Reliever (rescue) medications alleviate symptoms and prevent exercise-induced bronchoconstriction. Treatment must be based on a "stepwise approach" in order to achieve good control of symptoms and to minimise future risks of exacerbations. That is, less treatment for mild disease, more treatment for severe, uncontrolled disease. Once good asthma control has been achieved and maintained, treatment should be stepped down. In severe asthmatics, phenotypic characterisation becomes more clinically useful and add-on treatment such as anti-immunoglobulin E monoclonal antibodies may be required. Despite our better understanding of asthma, there are still patients who will not respond to treatment and remain symptomatic. Dissemination of guidelines and national plans allowing early diagnosis of asthma as well as access to specialised primary and secondary care for asthmatic patients, personalised treatment and continuity of care may lead to excellence in care and controlled asthma for the majority of patients. Education of the patient in asthma is also very important, as in every chronic disease, as the patients live with the disease every day while they visit a healthcare professional a few times a year. Future planning for new treatments should focus on the needs of such severe asthma patients.

Figure 1

Stepwise approach to the treatment of asthma. If control is not achieved with low-dose medication, higher doses and more classes of medication are prescribed in order to control asthma symptoms. Moreover, doses are kept at the minimum level that achieves good control in order to minimise future risk.

Figure 2

Asthma phenotypes identified using cluster analysis plotted according to their relative expression of symptoms and inflammation. The axes represent symptoms and inflammation. The disease is concordant when symptoms and inflammation increase in parallel. However some patients have discordant disease, i.e., a lot of inflammation requiring high doses of ICS but few symptoms, requiring little bronchodilation. And some patients have a lot symptoms but with little inflammation and therefore require bronchodilation but low ICS doses. So one size does not fit all! BMI: body mass index. Adapted from [4] with permission from the publisher.