Fig 4. Probability of severe asthma as a function of asthma duration, stratified by gender.

The probability of severe asthma in men [A] and in women [B] as a function of asthma duration stratified by age group comparing older asthma to young adult asthma. The fitted final logistic regression model, which included variables associated with severe asthma and adjusted for asthma duration, a history of Gastro-esophageal Reflux Disease (GERD) and a history of nasal corticosteroids, was used to calculate the probability of severe asthma. Young men and women have a 2% and 4%, increased risk of severe asthma per year of asthma duration, respectively. After age 45, the risk of severe asthma in women is not impacted by asthma duration, whereas risk of severe asthma in men continues to increase with increasing asthma duration.