Onset of asthma in severe asthma patients (PATH)

Study type

• Study type:
  Non-interventional study
• Scope of the study:
  Disease epidemiology

Non-interventional study

• Non-interventional study design:
  Cross-sectional

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:
  2000

Study design details

• Main study objective:
  The study aims to describe and compare the demographic and clinical features of early-onset vs late-onset asthma phenotypes in an international cohort of adult patients with severe asthma.
• Outcomes:
  The primary outcome is to describe the distribution of age of asthma onset in the international severe asthma cohort, define and validate the most appropriate age cut-off to delineate age-of-onset groups and to describe and compare the demographic and clinical characteristics of the early-onset vs late-onset asthma phenotypes in adult patients with severe asthma. The secondary outcome is to evaluate possible geographical differences in early-onset and late-onset asthma phenotypes in a severe asthma population.
• Data analysis plan:
  To define age cut-off, the study will explore the potential cut-offs through various methods including ROC curve analysis and best fitted model (highest area under the curve). Baseline characteristics will be reported for early-onset and late-onset asthma groups with continuous variables summarised using descriptive statistics, the frequency and percentages of observed levels will be reported for categorical variables, and tables will be annotated with the total population size. Characteristics of groups will be compared via contingency tables and group difference will be tested for statistical significance via chi-square tests for comparison of counts. Moreover, t-test or one-way analysis of variance (ANOVA) will be applied to compare means across groups. Demographic or clinical constructs will be compared between early-onset vs late-onset severe asthma phenotype groups.