From the late 1980s he worked as a health psychologist focusing on respiratory disease. He has constructed several outcome and management scales for use in respiratory disease, including the lung information needs questionnaire (LINQ), the DOSE index and most recently the severe asthma questionnaire (SAQ). His research in respiratory medicine includes studies on adherence to medication and its relation to outcome, and the management and outcome of severe asthma in relation to new treatments and the extra-pulmonary symptoms of severe asthma.