Background Smell testing is increasingly recognized as essential in rhinology practice but remains underutilized because of time constraints and limited clinical resources. This study aimed to evaluate the performance (test-retest reliability, accuracy and test completion time) of a self-administered, digital version of SMELL-RS, a non-semantic test of olfactory resolution (SMELL-R) and sensitivity (SMELL-S).

Methodology We performed a test-retest reliability study in a tertiary care facility. We enrolled 100 subjects with and without smell dysfunction. The primary outcome measures were two replicates of olfactory test scores (SMELL-RS composite score, SMELL-R score, SMELL-S score). The secondary outcome measures were Sniffin’ Sticks score, test completion time, patient demographics, and other clinical characteristics (clinical symptoms, etiologies).

Results The SMELL-RS composite score was reliable (ICC=0.71; p<0.0001) and correlated with the Sniffin’ Sticks composite score (r=0.68; p<0.0001). Different etiologies have different magnitudes of smell loss as revealed by the SMELL-RS score. SMELL-S reduces misdiagnosis associated with Sniffin’ Sticks threshold tests. The average completion time of the olfactory resolution test (SMELL-R) was on average 5.9 minutes (SD=1.9), while the average completion time of the olfactory sensitivity test (SMELL-S) was 5.5 minutes (SD=2.7). This is two to three times faster than the corresponding Sniffin’ Sticks tests.

Conclusions SMELL-RS is a rapid, fully automated, reliable, and accurate olfactory test suitable for self-administration in a clinical setting.

A.K. works as a consultant for Hynt Labs Limited. J.W.H and D.B are founders of UNBOOUND Medical Technologies SA. SMELL-RS is a patented technology from The Rockefeller University (US12364429B2 and EP3648613B1).

This study was funded by the Geneva University Hospitals, Department of Otorhinolaryngology. L.B.V. is supported by the Howard Hughes Medical Institute.

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Ethics committee of Commission Cantonale d'Ethique de la Recherche sur l'etre humain (Geneva, Switzerland) gave ethical approval for this work

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All data produced in the present study are available upon reasonable request to the authors