The role of inequalities in asthma care and outcomes in England: a cohort study of people with asthma

Study type
Date of Approval
Study reference ID
Lay Summary

Asthma is a disease that affects the lungs. Coughing and feeling out of breath are symptoms of asthma. The United Kingdom has one of the highest number of people living with asthma in the world. There is concern that differences in social status, wealth, ethnicity, and opportunities between different groups of people may impact asthma and how it is managed. As these differences have been getting worse over the last 10 years, it is important to understand how this affects people with asthma. One area which is important to study is how an individual's position in a society, determined by wealth, occupation, and social class, can affect people with asthma. This in turn will help to create strategies to improve the health of people with asthma with different backgrounds. We will use primary care data to look for differences in how people with asthma are managed at general practices and in hospital with different positions in society in England and how much this costs the National Health Service over time. We will also study whether there are differences by age, sex, and ethnicity. This project is a part of a three nation study (England, Scotland and Wales) and we will present our results alongside those from colleagues in Scoland and Wales, which will be conducted in parallel.

Technical Summary

Asthma is a chronic respiratory condition characterised by coughing, wheezing, chest tightness and breathlessness. The UK suffers from one of the highest rates of asthma prevalence in the world, with inequalities worsening over the last decade. Meanwhile, the UK economy has borne over £1 billion annually in treating and managing asthma. Few studies have investigated the role of inequalities in asthma care and outcomes. For example, a study in Wales assessed the association between socioeconomic status and asthma, but only in Wales and before COVID-19. To that end, we aim to extend the analysis undertaken in Wales to England as part of a bigger three UK nation study to understand asthma inequalities in the UK. Using CPRD Aurum primary care data linked with hospital episode statistics (HES) APC, A&E, and ONS mortality and socioeconomic status data, we will investigate the association between Index of Multiple Deprivation and asthma care and outcomes including number of hospital admissions, A&E admissions, exacerbations, GP prescriptions and consultations, and mortality, adjusting for sex, age and ethnicity. We will fit negative binomial multilevel models to estimate the incidence rate ratio for variables that represent the count of asthma-related events within a given Index of Multiple Deprivation quintile compared to the least deprived quintile. We will fit survival models to determine factors associated with asthma-related death. We will also perform an economic analysis to estimate the direct costs of asthma inequalities from a healthcare system perspective. In addition, we will use time series techniques to investigate whether the magnitude and patterns of asthma inequities have changed over the last decade, including during the pandemic. We will present our results alongside comparable analysis of Scottish and Welsh data, which will be conducted in parallel, by project partners in each respective nation.

Health Outcomes to be Measured

The following outcomes will be investigated during the follow-up period:

Primary outcomes:
1) Asthma-related health service utilisation:
-Number of General Practice (GP) consultations
-Asthma exacerbations (defined as a GP or hospital admission for acute exacerbations of asthma or a GP prescription of an oral corticosteroid and respiratory-related antibiotic)
-Emergency department attendances (asthma-specific and all-cause)
-Number of hospital admissions
-Number of emergency and non-emergency hospital admissions
-Length of hospital stay
-Intensive Care Unit (ICU) admission

2) Asthma prescriptions:
-Maintenance medications (including inhaled corticosteroids, long acting beta agonists, long acting muscarinic antagonists and their combinations)
- Short acting asthma medications (short acting beta agonists, short acting muscarinic antagonists)
-Asthma medication ratio (AMR) (controller-to-total medications)

3) Mortality:
- All-cause mortality

Secondary outcomes include unit costs for asthma-related health service utilisation events and prescriptions according to the National Health Service (NHS) References Costs and the National Cost Collection.


Jennifer Quint - Chief Investigator - Imperial College London
Hannah Whittaker - Corresponding Applicant - Imperial College London
Zakariah Gassasse - Collaborator - Imperial College London


HES Accident and Emergency;HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation