Multimorbidities in Allergic Rhinitis-Current Evidence from Epidemiological Studies, Treatment Trials, and Molecular...

Given that allergic rhinitis (AR) commonly coexists with other diseases, the present narrative review attempts a brief presentation of current theories on multimorbidities in relation to phenotypes, genotypes, age, and treatment responses with the term "multimorbidities" indicating the uncertainty regarding the primary defect, organ, or pathophysiologic mechanism involved.

Though age-related manifestations allow for the generation of several hypotheses on AR's specific mechanisms, the various theories regarding the initiation or the aggravation of atopic disorders have yet to be proved. Multimorbid AR seems to have a different genetic basis from "stand-alone" AR as well a more severe phenotype. Most studies on the treatment of AR and its multimorbidities focus on allergen immunotherapy, which improves the atopic symptoms and may play a preventive role in the onset of new allergen sensitizations. The use of biological factors may also have a beneficial effect, even though it has currently been approved only for some comorbidities of AR, such as asthma. Employing the use of phenotypes and genotypes concerning multimorbidity broadens current knowledge, but further research is needed to develop diagnostic, stratificational, and predictive algorithms for single and multimorbid allergic diseases (Fig. 1). The real-time data obtained by mobile apps and the new insights on the pathophysiology of AR and its comorbidities will permit both timed preventive measures and better individualized and effective antiallergic treatment. Fig. 1 Current concepts and future trends in diagnosis and management of multimorbid allergic rhinitis.