xRead - Olfactory Disorders (September 2023)

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PATEL et al.

TABLE VII.3 Section evidence summary: CRS related olfactory loss in relation to endotypic factors

Endotypic factors associated with olfactory findings IL-5 was associated with worse overall SS-TDI score and identification CLC protein gene expression was associated with worse UPSIT R and threshold scores IL-2, IL-5, IL-6, IL-10 and IL-13 were significantly associated with SIT scores A cluster characterized by high IL-5 and IL-13 levels had significantly higher objective olfactory deficit; however, IL-5 and IL-13 alone were not independently associated when AERD status and CT score were modeled Preoperative eosinophilia was associated with objective olfactory decline IL-5, IL-6, IL-13, IL-9, IL-10, IL-23, CCL2, CCL3, and IgE were associated with TDI score Correlations between

Sample studied and olfactory testing method

Study

Year LOE Study design

Study groups

Schlosser 180

OCmucus SS-TDI

2016 2

Cross-sectional

34 patients: 19 with CRSsNPand with 15 CRSwNP controls, 10 with CRSsNP, and 13 with CRSwNP 30 patients: 7

Lavin 177

2017 2

Cross-sectional

Superior turbinate tissue UPSIT R and SS-T before ESS OCmucus UPSIT R beforeESS Middle meatal mucus UPSIT R beforeESS

Wu 179

2018 2

Cross-sectional

67 patients: 31 CRSsNP, 36 CRSwNP 110 patients: 49 with CRSsNP and61with CRSwNP

Morse 216

2019 2

Cross-sectional

Wu 217

Superior turbinate mucosa SS-TDI

2020 2

Longitudinal after sinus surgery

76 patients: 36 with CRSsNP and 30 with CRSwNP 62 patients: 25 with CRSsNP and 37 with CRSwNP

Soler 183

2020 2

Cross-sectional

OCmucus SS-TDI

inflammatory mediators and olfaction only were observed among patients with CRSwNP

AERD = aspirin-related respiratory disease; CCL = chemokine (C-C motif) ligand; CLC = Charcot-Leyden crystal; CRS = chronic rhinosinusitis; CRSwNP = chronic rhinosinusitis with nasal polyps; CRSsNP = chronic rhinosinusitis without nasal polyps; ESS = endoscopic sinus surgery; CT = computed tomography; IL = interleukin; LOE = level of evidence; OC = olfactory cleft; SIT = Smell Identification Test; SS-T = Sniffin’Sticks threshold only; SS-TDI = Sniffin’ Sticks threshold, discrimination, identification; TDI = threshold, discrimination, identification combination; UPSIT R = University of Pennsylvania Smell Identification Test.

pared with healthy individuals (odds ratio, 4.88). 224 In a systematic review of 36 studies, OD was observed in 10% to 90% of patients with AR, with most studies reporting between 20% to 40%. 225 This finding is corroborated among pediatric populations; one study identified a significant increase in OD only for pediatric patients whose symptoms exceeded 3 years. 226–229 One explanation for the wide range of OD in this population is that some studies have included patients with comorbid CRS. A variety of subjective and objective metrics have been used to assess OF in patients with rhinitis. The severity of OD is typically within the mild to moderate range; true anosmia is rare. 225,230,231 Patients with peren nial AR or non-AR exhibit symptoms of OD year-round. On the other hand, patients with seasonal AR exhibit hyposmia during allergy season, with normalization of

tory deficit and provide the impetus for endotyping-based approaches to study CRS-associated olfactory loss. CRS endotyping is associated with OF. Aggregate grade of evidence : C (Level 4: five studies). 3 Related to AR or CRS Extensive evidence supports the association between rhi nosinusitis and OD, although the prevalence of OD in patients with rhinitis varies significantly in the literature. In a large population study in Sweden, subjective hypos mia was reported by ≈ 30% of patients with non-AR, 13% with AR, and 12% of healthy individuals. 223 In South Korea, a diagnosis of OD was strongly associated with AR com