Patients should be referred if any of the following are present:

• doubt about the diagnosis of asthma
• uncontrolled asthma symptoms despite optimal management
• suspected co-morbidity such as a component of heart failure, suspected malignancy, coexisting COPD
• difficult asthma with persistent symptoms despite the use of optimal therapy advocated at step 4 on the BTS algorithm and beyond
• new diagnosis in patients older than 65 years of age with multiple medical problems
• asthma requiring repeated hospital admissions due to worsening of asthma symptoms over the previous year that is deemed to need a specialist evaluation
• elevated specific plasma IgE level raising the possibility of allergic bronchopulmonary aspergillosis
• patients receiving oral steroids or requiring treatment with immunosuppressants or monoclonal antibodies
• systemic symptoms raising the possibility of asthma being part of a vasculitic condition
• the need to confirm or rule out occupational asthma: consider occupational asthma in all adults with a new diagnosis of asthma, with the clinician alerted by a positive answer to the question: ‘‘Is your asthma better away from work?’’