Definition and characteristics of acute exacerbation in adult patients with chronic rhinosinusitis: a systematic review

BACKGROUND: Acute exacerbations (AE) in chronic rhinosinusitis (CRS) have been increasingly recognized as an important clinical issue. The purpose of this study is to summarize the current definitions and evaluation parameters of AE and then identify and quantify the clinical and immunopathologic characteristics of AE in CRS. METHODS: A systematic review of the literature was performed on PubMed, Scopus, and Cochrane databases from January 1990 through August 2020 to identify studies relating to AE in CRS. Exclusion criteria included non-English and non-human studies, and case reports. RESULTS: The definitions of AE in CRS among all the studies were based on a description of short-term worsening sinonasal symptoms. Patient-reported sinus infection and exacerbation related medical treatment during the preceding 3 months to 1 year were used to evaluate the frequency of AE in CRS. The average decline in 22-item Sino-Nasal Outcome Test (SNOT-22) score during an exacerbation was 7.83 points relative to baseline. Comorbid asthma, SNOT-22 scores ≥24, allergic rhinitis, eosinophil count ≥150/μL and autoimmune disease were positively associated with an exacerbation-prone CRS phenotype. AE in chronic rhinosinusitis with nasal polyps (CRSwNP) was associated with increased expression of mucus cytokines including myeloperoxidase (percentage increase [PI] = 101%), IL-5 (PI = 125%), and IL-6 (PI = 162%) and could be predicted by the increasing mucus cystatin and periostin. CONCLUSION: The definition of AE in CRS is largely driven by patient-reported symptoms and is associated with several risk factors. Quantitative changes in mucus cytokines associated with AE in CRSwNP and may be used to predict events. The development of a consistent definition of AE in CRS is critical to help define disease control and treatment efficacy.