In the UK, someone experiences a potentially life-threatening asthma attack every ten seconds, while every day three people die from asthma. Although some of these events could be prevented with daily inhaled corticosteroid (ICS) treatment, some patients continue to suffer from severe asthma despite good compliance.
A previous study conducted by the Observational and Pragmatic Research Institute (OPRI) found that patients with asthma and high blood eosinophil counts experience more severe exacerbations and have poorer asthma control.
We aim to further investigate the association between high blood eosinophil counts and prospective asthma disease burden with two objectives:
1. To study whether high blood eosinophil counts are a risk factor for asthma attacks at all levels of ICS treatment, including among patients adherent to medium to high dose ICS
2. To study whether patients admitted to hospital with asthma exacerbations are more likely to be re-admitted if their pre-admission eosinophil count is high
This study will provide evidence on how to identify patients at high risk of asthma attacks and may provide a rationale for alternative therapy options, such as biologic therapy targeting eosinophils, in patients with asthma who do not respond well to current guideline-recommended therapy.
Objectives:
To study whether:
1. High blood eosinophil counts are associated with subsequent increased asthma exacerbation frequency at all levels of ICS treatment.
2. Patients admitted to hospital with asthma exacerbation are more likely to be re-admitted if their pre-admission eosinophil count is high
Methods:
Objective 1: Patients with active asthma (≥2 drug prescriptions in the baseline year prior to index date (ID)) will be selected from both CPRD and the Optimum Patient Care Research Database.
Objective 2: CPRD patients with HES Admitted Patient Care data will be selected.
Objective ID: most recent date of Primary Outcome Outcome Period
1 Eosinophil count recording Number of exacerbations 1 & 3 years
2 First hospital discharge for asthma within 1 year of eosinophil measurement Occurrence of re-admission for asthma 4 & 52 weeks
Patients will be characterised and confounders will be assessed during the baseline year. Adjusted associations with 95% confidence intervals will be assessed from multiple regression analyses.
Objective 1: Rate Ratios (RR) by negative binomial regression analysis for patients on low, medium and high dose ICS separately. Analyses will be repeated in patients with good ICS adherence (Medication Possession Ratio ≥80%).
Objective 2: Hazard ratios (HR) by Cox regression analysis.
• Asthma exacerbations • Excessive short-acting bronchodilator use • Hospitalisations for asthma • Acute respiratory events
David Price - Chief Investigator - OPRI - Observational and Pragmatic Research Institute Pte Ltd
Marjan Kerkhof - Corresponding Applicant - OPRI - Observational and Pragmatic Research Institute Pte Ltd
Andrew Menzies-Gow - Collaborator - Royal Brompton Hospital
Derek Skinner - Collaborator - Research in Real Life ltd.( RiRl )
Gopalan Gokul - Collaborator - Astra Zeneca Inc - USA
Guy Brusselle - Collaborator - Ghent University Hospital
Janwillem Kocks - Collaborator - University Medical Centre Groningen
Javier Nuevo - Collaborator - Astra Zeneca Inc - USA
Rupert Jones - Collaborator - Plymouth University
Sarang Rastogi - Collaborator - Astra Zeneca Inc - USA
Trung Tran - Collaborator - Astra Zeneca Inc - USA
HES Admitted Patient Care