Current Review of Comorbidities in Chronic Rhinosinusitis.

Purpose of review: Chronic rhinosinusitis (CRS) is a heterogenous disease with a significant impact on patient quality of life and a substantial economic burden. CRS is associated with several systemic inflammatory conditions. We provide an updated review of CRS comorbidities as a springboard for future comorbidity mapping and potential therapeutics.

Recent findings: The link between environmental allergies and CRS is most evident for central compartment atopic disease (CCAD) and allergic fungal rhinosinusitis (AFRS) subtypes but remains inconclusive for CRS overall. The association between asthma and CRS, reinforced by the unified airway theory, is evidenced by their response to similar biologic therapies. Another lower respiratory tract disease, COPD, has up to a 50% co-occurrence with CRS and warrants careful screening and treatment. Eosinophilic esophagitis and CRS share eosinophilic inflammation in different sites, meriting further research. Obesity not only presents physiological challenges but also correlates with a more severe subset of CRS. Diabetes mellitus is associated with CRSwNP, possibly secondary to therapeutics with steroids. Autoimmunity may contribute to nasal polyp formation through cytokines such as B-cell activating factor (BAFF), offering potential for future therapeutics.  This review illustrates the need to employ a macroscopic approach in clinical decision making and treatment of CRS. Comorbidities may contribute to an overall proinflammatory state, magnify severity of symptoms, be a source of treatment resistance, and even an opportunity for future therapeutics.