Model parameters Base case value Range for DSA Range for DSA Distribution Reference
Lower Upper
Transition probabilities (per 3-month cycle)
ICS
 GINA Step 3 to GINA Step 2 0.025 Beta (23,25)
 GINA Step 2 to asthma without medications 0.041 0.000 Beta (23)
SCIT+ICS
 GINA Step 3 to GINA Step 2 0.024 0.458 Beta (23,25,37)
 GINA Step 2 to asthma without medications 0.155 Beta (23,25)
Frequency of asthma exacerbations
 Baseline probability of an asthma   exacerbation in patients with AA 0.095 Beta (43)
 Baseline probability of an asthma   exacerbation in patients with AA+AR 0.145 (43)
 Reduction in probability of asthma   exacerbation due to SCIT 0.504 0.500 0.900 Beta (29)
 Baseline rate of severe exacerbations per   year 1.5 Lognormal (3)
 Baseline rate of moderate exacerbations   per year 1.3 Lognormal (3)
 Length of a moderate exacerbation (days) 7.0 Lognormal (18)
 Length of a severe exacerbation (days) 10.2 Lognormal (44)
Health state utilities
 GINA Step 3 0.630 0.400 0.860 Beta (35)
 GINA Step 2 0.700 0.500 0.900 Beta (35)
 Asthma without medications 0.890 0.790 0.990 Beta (35)
Exacerbation-related disutilities
 Hospitalization -0.200 Lognormal (36)
 ED visit -0.100 Lognormal (36)
Costs per year or event (2018 USD)
 Subcutaneous immunotherapy ($27.8 per   administration) $ 334.4 $ 22.3 $ 33.2 Gamma (34)
 GINA Step 3
 Pediatric patients (8-11y) $ 43.2 Gamma (33,34)
 Adults and adolescents (>=12y) $ 52.2 Gamma (33,34)
 GINA Step 2
 Pediatric patients (8-11y) $ 32.1 Gamma (33,34)
 Adults and adolescents (>=12y) $ 36.6 Gamma (33,34)
 Asthma without medications $ 20.1
 ED visit $ 23.3 Gamma (33,34)
 Hospitalization $ 154.0 Gamma (33,34)