1. Global Initiative for Asthma . Global strategy for asthma management and prevention. Available online at www.ginasthma.org/local/uploads/files/GINA_Report_2014_Aug12.pdf [Accessed 19 March 2015].
2. The prevalence of severe refractory asthma;Hekking;J Allergy Clin Immunol,2015
3. Severe asthma treatment: need for characterising patients
4. International ERS/ATS guidelines on definition, evaluation and treatment of severe asthma
5. NHS England . A14/S/1b – 2013/14 NHS standard contract for respiratory: severe asthma (adult). Available online at www.england.nhs.uk/wp-content/uploads/2013/06/a14-respiratory-sev-asthma.pdf [Accessed 19 March 2015 ].