Longitudinal improvement and stability of olfactory function in the evaluation of surgical management for chronic rhinosinusitis

Background Abnormal olfaction is common with chronic rhinosinusitis (CRS) and associates with various measures of sinonasal inflammation. The Brief Smell Identification Test (BSIT) has demonstrated improvements in abnormal olfactory detection following endoscopic sinus surgery (ESS), but olfaction remains understudied using this instrument. Discerning longitudinal, postoperative durability in olfaction is critical for patient counseling. Methods Adult participants with medically recalcitrant CRS were prospectively enrolled into a multi‐institutional cohort study and observed for 18 months after ESS. Olfaction was operationalized using BSIT scores collected at baseline, 6 months, 12 months, and 18 months postoperatively and compared using repeated measures analysis of variance (ANOVA). Results A total of 122 participants met inclusion criteria and were recruited between March 2011 and February 2014. Improvement in mean BSIT scores at 6‐month follow‐up were reported for all participants (p = 0.014) with greatest improvement in subjects with nasal polyposis (p = 0.001). No differences in mean BSIT scores were found between 6 months and 18 months overall; however, subjects with comorbid asthma (F(2) = 5.29; p = 0.010) and nasal polyposis (F(2) = 3.99; p = 0.033) reported significant mean worsening. Prevalence of abnormal olfaction decreased from 28% preoperatively to 17% at 6 months (p = 0.015), for all subjects, without significant change at 12 months (19%; p = 0.791) or at 18 months (21%; p = 0.581) postoperatively. Conclusion Postoperative improvement in olfaction was reported 6 months after ESS using BSIT scores, with greatest improvements in patients undergoing polypectomy. Overall improvement persisted between 6 months and 18 months after ESS for most patient subgroups; however, dysosmia worsened after initial improvement in patients with asthma and nasal polyps, highlighting the need for further identification of prognostic factors associated with abnormal olfaction in CRS.