BACKGROUND: Viral infection and allergy have been identified as major risk factors for exacerbation in asthma, especially in the presence of both. However, whether patients with allergic asthma are more susceptible to respiratory infections requiring antibiotics remains unknown.
OBJECTIVE: To investigate allergy as a risk factor for respiratory infections requiring antibiotics based on register data from a nationwide population of patients with asthma.
METHODS: A register-based prospective follow-up study was performed using the Danish prescription database. In the inclusion period from 2010 through 2011, we identified patients with allergic asthma 18 to 44 years old. Patients were investigated during the follow-up period from 2012 through 2013, depending on their prescription drug use of antiallergic medication and antibiotics. Odds ratios were adjusted for age, sex, asthma severity, education, and urban vs rural residence.
RESULTS: In a nationwide population we identified 60,415 patients with asthma. Based on prescriptions fillings for antiallergic medication, patients were subdivided into (1) nonallergic asthma (n = 35,334, 51.5%) and (2) allergic asthma (n = 25,081, 48.5%). Allergic asthma was associated with an increased risk of filling at least 2 antibiotic prescriptions per year compared with nonallergic asthma (odds ratio 1.28, 95% confidence interval 1.24-1.33, P < .0001). Interestingly, a subgroup analysis showed a protective effect of immunotherapy against the risk of requiring antibiotics (odds ratio 0.76, 95% confidence interval 0.66-0.87, P = .0001).
CONCLUSION: Patients with allergic asthma have an increased risk of being prescribed antibiotics for respiratory infections compared with those with nonallergic asthma. Treatment with allergen immunotherapy appears to have a protective effect against this risk.