BACKGROUND: Allergic asthma causes substantial morbidity and constitutes a public health burden, which increases with asthma severity. There is evidence that allergy immunotherapy (AIT) prevents the progression of allergic rhinitis (AR) to asthma. However, evidence is missing on the potential of AIT to prevent progression from milder to more severe asthma.

METHODS: This population-based cohort study utilized healthcare data (2005 to 2014) from a statutory health insurance in Germany. The severity of asthma was classified according to the treatment steps recommended by the global initiative for asthma (GINA). The effect of AIT on the transition between the GINA steps was analyzed using multivariable Cox regression models adjusted for age and sex.

RESULTS: From the total cohort of 1,739,440 patients, 39,167 individuals aged 14 years or older were classified as having incident asthma during the observation period and were included in the study. From these, 4111 patients (10.5%) received AIT. AIT exposure was associated with a significantly decreased likelihood of asthma progression from GINA step 1 to GINA step 3 (HR 0.87; 95% CI 0.80-0.95) and GINA step 3 to GINA step 4 (HR 0.66; 95% CI 0.60-0.74). GINA medication for step 2 and step 5 was rarely prescribed.

CONCLUSIONS: This observational study in a real-world setting indicates that patients with allergic asthma who receive AIT are less likely to experience progression of asthma severity than asthma patients not receiving AIT.