Study type

Study type

Non-interventional study

Scope of the study

Disease epidemiology
Non-interventional study

Non-interventional study design

Cohort
Study drug and medical condition

Medical condition to be studied

Asthma
Population studied

Age groups

Adults (18 to < 46 years)
Adults (46 to < 65 years)
Adults (65 to < 75 years)
Adults (75 to < 85 years)
Adults (85 years and over)

Estimated number of subjects

100000
Study design details

Main study objective

This study aims to investigate whether the burden of severe asthma exacerbations is associated with lung function decline in asthma patientsThe main objective of this study is to assess the role of exacerbation burden as a predictor of lung function declined in asthma patients with at least 5 years of lung function recording (follow-up) and 3 or more lung function readings (spirometry or PEF)

Outcomes

Lung function decline measured by Forced expiratory value in 1 second (L) and/or Peak expiratory flow rate (L/minute).

Data analysis plan

The study will assess a historical cohort of patients diagnosed with asthma, who have 3 or more of either PEFR or FEV1 readings taken over a minimum of 5 years from their 18th birthday. The index date, i.e. the start of follow-up, will be the first date on which a lung function reading is recorded after age 18. Baseline is defined as the year prior to and including the index date.The association between exacerbation burden and lung function will be explored under a mixed-effects regression modelling approach. The variation in lung function trajectories between individual study subjects is accounted for by including a random intercept and slope of lung function over time at the patient level in the model. The relationship between exacerbation burden and the slopes of lung function is modelled by the interaction term of exacerbation burden and follow up time in years in the mixed effects model. Non-linear trajectories will be considered by the inclusion of time polynomials in the model