Prevalence of poorly controlled asthma and factors associated with specialist referral in those with poorly controlled asthma in a paediatric asthma population.

Date of Approval
Application Number
Technical Summary

Our objective is to better understand the burden of poorly controlled asthma, overall and among those with severe asthma (GINA steps 4 and 5) and to see if this has changed over time. In addition, we will investigate which factors may be associated with referral to specialists in those with poor asthma control. This will help to inform better referral pathways and management for asthma patients.

We will include a cohort of asthma patients aged 6–18 years and describe the proportion who have poor control, both overall and by disease severity (defined by asthma medications using the Global Initiative for Asthma (GINA) steps where steps 1–3 represent mild asthma and steps 4&5 severe asthma). We will investigate time to specialist referral in those with poor control and assess factors that may be associated with specialist referral. Poor control will be defined as at least one of: ≥2 courses of OCS / hospital admissions / A&E attendances in past 12 months, (i.e. asthma exacerbations), prescription of ≥6 SABA inhalers in past 12 months, FEV1/FVC <80%, or ACT/cACT <20.

We will use CPRD Aurum data linked with HES APC, HES A&E, HES OP and IMD data. The study period will be 2007–2019. We will calculate time to referral in the group of children with poor control. We will use Cox regression to compare time to referral in severe versus mild asthma patients. In the Cox model, we will adjust for sex, age, socioeconomic status, co-morbidities and possibly region. We will also undertake conditional logistic regression to determine factors associated with specialist referral using a nested case–control study design.

Health Outcomes to be Measured

Specialist referral defined as:
- Hospital respiratory clinics or paediatric clinics or allergy clinics
- CPRD asthma referral codes


Jennifer Quint - Chief Investigator - Imperial College London
Jennifer Quint - Corresponding Applicant - Imperial College London
Ann Morgan - Collaborator - Imperial College London
Constantinos Kallis - Collaborator - Imperial College London
Louise Fleming - Collaborator - Imperial College London


HES Accident and Emergency;HES Admitted Patient Care;HES Outpatient;Patient Level Index of Multiple Deprivation