The association between allergy and chronic rhinosinusitis with and without nasal polyps: An evidence-based review with recommendations

Background: The relationship between allergy and chronic rhinosinusitis (CRS) remains ill-defined and controversial. The association between the 2 is unclear, making an evidence-based decision of whether to evaluate and treat allergies in CRS patients difficult. The purposes of this systematic review are to (1) examine the relationship between allergy and CRS without nasal polyps (CRSsNP), (2) examine the same for allergy and CRS with nasal polyps (CRSwNP), and (3) recommend evaluation and treatment based on the evidence. Methods: A structured literature search was performed to identify articles examining the link between allergy and CRSsNP and CRSwNP. Pertinent articles were examined for evidence for an association between allergy and CRSsNP and/or CRSwNP. Results: A total of 24 articles were found that met the inclusion criteria; 18 articles examined the relationship between allergy and CRSwNP, with 10 articles showing an association, 7 articles showing no association, and 1 article showing a possible association. Nine articles examined the relationship between allergy and CRSsNP, with 4 articles showing an association and 5 articles showing no association. Four studies directly compared the role of allergy in CRSwNP and CRSsNP, and, again, the results were mixed. No articles examined the outcomes of CRSsNP or CRSwNP following allergy treatment. Conclusion: The role of allergy in CRSwNP and CRSsNP continues to be controversial, with the level of evidence poor. Based on the available data, the recommendation is that allergy testing and treatment are an option in CRSwNP and CRSsNP.