Olfactory changes after endoscopic sinus surgery for chronic rhinosinusitis: A meta-analysis

Background Endoscopic sinus surgery (ESS) is an important treatment modality for chronic rhinosinusitis (CRS). However, its effect on olfaction remains controversial. Objective of review To assess the olfactory impact of ESS in patients with CRS. Type of review A meta-analysis. Search strategy A systematic literature search in the PubMed, EMBASE and Cochrane Library databases was conducted to identify studies that assessed change in olfaction after ESS in patients with CRS. Search terms were related to paranasal sinus diseases, smell and endoscopy. Evaluation method The extracted data included authors, publication year, study type, age, sex, diagnostic criteria, surgical mode, sample size, follow-up time, olfaction measurement tool and outcome. We analysed the olfactory changes as continuous variables. Results Thirty-five studies including 3164 patients with CRS were eligible for the meta-analysis. Among patients having CRS with nasal polyps, olfactory dysfunction improved, as assessed by the Sniffin' Sticks total score (P = .000), Sniffin' Sticks discrimination score (P = .023), Sniffin' Sticks identification score (P = .005), University of Pennsylvania Smell Identification Test (P = .046) and Visual Analogue Scale (P = .000). However, the threshold score of the Sniffin' Sticks test did not improve significantly (P = .361). Olfactory dysfunction did not improve in patients having CRS without nasal polyps according to the University of Pennsylvania Smell Identification Test (P = .404). In non-classified CRS patients, improvement in olfactory dysfunction was observed according to the University of Pennsylvania Smell Identification Test (P = .000), Visual Analogue Scale (P = .001) and Questionnaire of Olfactory Disorders-Negative Statements (P = .001). However, there were no significant improvements according to the Brief Smell Identification Test (P = .325), Sniffin' Sticks threshold score (P = .160) and Sniffin' Sticks identification score (P = .079). Conclusion Endoscopic sinus surgery may be beneficial for improvement in olfactory conditions in patients with CRS. Further thorough and comprehensive studies need to be conducted.