Asthma is the most common chronic lung disorder in the UK; approximately 1 in 9 people have received an asthma diagnosis. The mainstay of treatment is regular inhaled medication, called maintenance medication, which aims to prevent daily asthma symptoms (including breathlessness, wheeze and cough) and asthma attacks (sudden worsening of symptoms requiring urgent treatment). If an asthma patient does not have many symptoms, and only infrequently uses their asthma reliever medication (gives immediate symptom relief), the patient is described as having well-controlled asthma. Once a patient is well controlled, i.e. has stable asthma, guidelines recommend considering reducing their maintenance medication to reduce the risk of side effects; for example, all maintenance medications include inhaled corticosteroids (side effects include voice hoarseness, cataracts or slowed growth in children). However, recent nationally-recognised medical reviews have concluded there is insufficient evidence from trials as to whether stepping down (reducing) asthma treatment is beneficial or not. Our study aims to, firstly, determine how common stepping down (reducing) asthma treatment is in UK clinical practice, and secondly, estimate the effect of this clinical practice on asthma attacks, and asthma control, in the real-world.
We will used CPRD to identify asthma patients and their medication, and describe how often patients step down, or step up, their maintenance asthma medication, according to British asthma clinical guidelines, between 2000 and 2016. We will use a Poisson regression model to identify factors associated with stepping down, and stepping up, asthma maintenance medication.
Next we will use CPRD, linked with HES and ONS, to conduct a matched cohort study, the exposures will be stepping down asthma treatment, according to clinical guidelines, and the main outcome will be asthma attacks (treated in primary and secondary care). A secondary outcome will be stepping asthma treatment back up. Patients will be matched by GP practice, asthma severity, age and gender. A Cox proportional hazards model will be used to estimate the hazard ratios and their corresponding 95% confidence intervals. Multiple potential confounders or effect modifiers will be included in the model to obtain adjusted estimates, and to identify factors affecting the association between the exposure and the outcomes.
Asthma attacks
Reducing asthma medication
Increasing asthma medication
Jennifer Quint - Chief Investigator - Imperial College London
Chloe Bloom - Corresponding Applicant - Imperial College London
HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation