Risk of Adverse Events and Costs Associated with Chronic Systemic Corticosteroid Use in UK Patients with Severe Asthma

Trial description: Approximately 5-10% of asthma patients have severe asthma and less than 5% of the total asthma population has severe refractory asthma (SRA). SRA is defined as the inability to achieve adequate asthma control despite maximal pharmacologic therapy with high dose inhaled corticosteroid (ICS) plus a second controller and/or systemic corticosteroids (SCS) to prevent asthma from becoming ‘uncontrolled’ or asthma that remains ‘uncontrolled’ despite this therapy. Prior research has shown that patients with more severe asthma incur higher economic burdens and incur costs that may be as much as 4.6 times more than those with mild disease. Those SRA patients experiencing exacerbations have been shown to have cost burdens 3.5 times those not exacerbating. As indicated by treatment guidelines, many patients with SRA are exposed to intermittent and/or chronic dosing with SCS therapy. While highly effective in the treatment of asthma, the use of corticosteroids can lead to the development of significant systemic adverse events (AEs). According to data from the Healthcare Cost and Utilization Project, corticosteroids were among the most common cause of drug-related AEs prior to hospital admission, accounting for 9.6% of all pre-admission drug-related AEs in the United States in 2011. While the cost for SCS is very low, the costs associated with the treatment of SCS related AEs are unknown.In an effort to more fully evaluate the potential of these new therapeutic agents to improve patient care through reduction in SCS use, it will be important to determine the degree to which SCS use impacts the risk of AEs and costs in the SRA population.Objectives: 1. In the UK Clinical Practice Research Datalink (CPRD) population, assess the impact of chronic SCS use controlling for SCS dose intensity on the development of key AEs among a severe asthma population.2. In the UK CPRD population estimate the total incremental healthcare costs associated with the use of chronic SCS therapy controlling for measures of SCS dose intensity among a severe asthma population.3. Assess the difference in relative risk of SCS related AEs and total incremental costs associated with SCS use for severe asthma patients identified as eligible to receive Mepolizumab compared to patients not eligible for Mepolizumab.This analysis will be conducted using a retrospective longitudinal cohort design. Medical diagnosis and prescribing data from the CPRD will be used for the analysis. The overall cohort will be defined as a group of patients with moderate to severe asthma as defined by the guidelines of the British Thoracic Society, category 4 or 5 (BTS 4/5). In order to align the study population to the chronic SCS using population in the Mepolizumab clinical trial programs, a prevalent user design will be employed that identifies chronic SCS users among the severe asthma population. The time period used for this study will extend from January 1, 1997 to December 31, 2013. Those patients using chronic SCS therapy will be propensity score matched to patients with severe asthma who are not chronic users of SCS. It is important to note that within the cohort of severe asthma patients, non-chronic SCS users may or may not have used SCS since being diagnosed with severe asthma. In this way the analysis will determine rates of AEs and costs among chronic SCS users and the ‘general’ severe asthma population. Several key periods will be defined within the cohort.