Correlation of forced expiratory volume in one second with mortality and resource use in patients with asthma

Date of ISAC Approval: 
Lay Summary: 
Asthma is a chronic lung condition affecting over 5 million people in the UK. It is caused by inflammation of the airways which leads to symptoms such as wheezing, breathlessness and coughing. Asthma can vary in severity from mild to severe and can be life threatening with approximately 1,400 deaths due to asthma occurring in the UK each year. The aim of this study is to use data from the Clinical Practice Research Datalink to identify patients with asthma and to determine how well their lungs operate based on a test that measures how much air a person can breathe out in one second (forced expiratory volume in one second (FEV1)). We will look at how this measurement is associated with deaths related and unrelated to asthma, and how often patients use NHS services following an asthma attack. This will provide valuable data to inform the development of therapies to help people with asthma.
Technical Summary: 
We aim to study patterns of mortality for patients with asthma and determine the association with measurements of forced expiratory volume in one second (FEV1)). The primary objective is to determine if FEV1 is related to mortality risk in patients with asthma who have had a prior asthma exacerbation. Secondary outcomes are to assess the impact of FEV1 measurements upon non-exacerbation related mortality and all-cause mortality; and the corresponding resource use. Data will be selected from the Clinical Practice Research Datalink including linked Hospital Episode Statistics admitted patient care and accident and accident and emergency data and ONS mortality data. Subjects with asthma will be selected from between 2000-2016 by clinical code (Read code in CPRD GOLG and ICD-10 in HES). For the primary objective, patients with a moderate asthma exacerbation (based upon prescription of oral corticosteroid) and/or severe asthma exacerbation (based on inpatient or accident and emergency admission) will be identified and their previous recorded FEV1 used to stratify mortality risk in a logistic regression model. Time dependent Cox proportional hazard models will be created for the secondary mortality outcomes with FEV1 recorded as a quarterly segmented variable. Post-exacerbation resource use will be aggregated and costed using published tariffs and compared by prior FEV1 groupings.
Health Outcomes to be Measured: 
- mortality

Dr Christopher Morgan - Chief Investigator - Pharmatelligence
Miss Bethan Jones - Corresponding Applicant - Pharmatelligence
Dr Sara Jenkins-Jones - Collaborator - Pharmatelligence

HES A&E;HES Admitted;ONS;Patient IMD