Patients with refractory asthma represent a significant unmet clinical need where treatment options are limited and effective management poses a challenge. Treatment with daily systemic corticosteroids is the norm for many patients. Subsequently they are at risk of many significant and potentially life threatening adverse effects of systemic corticosteroid use. Little evidence is available surrounding this issue in a severe or refractory asthma population. Using data from the British Thoracic Society Difficult Asthma Registry and the Optimum Patient Care Research Database, the aims of this thesis' were to determine the prevalence of systemic corticosteroid dependency in refractory asthma and the direct healthcare costs associated with this cohort and finally to identify the prevalence I of systemic corticosteroid induced morbidity in refractory asthma. We identified that ca 52% of patients with refractory asthma in the UK are receiving daily doses of systemic corticosteroids. We found that the economic costs of patients with severe refractory asthma attending specialist difficult asthma centres are substantial and outweigh the costs of patients with difficult to treat asthma. Furthermore, we determined the cross-sectional prevalence rates for adverse effects which are commonly related to systemic corticosteroid use in severe refractory asthma including type 11 diabetes, osteoporosis, gastric disorders, obesity, hypertension and obstructive sleep apnoea. These are Significantly greater in subjects with severe asthma who require daily systemic corticosteroids, compared to subjects with severe disease using intermittent rescue corticosteroids and well-controlled asthma In conclusion, we have identified that refractory asthma represents a substantial burden to the NHS as well as being associated with many adverse effects related to systemic corticosteroid exposure. The need for better targeting of steroid therapy in asthma using objective biomarker based strategies and the urgent delivery of novel therapies which will both reduce exposure to systemic corticosteroids and the overall burden of disease are critical