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The 8-Odorant Barcelona Olfactory Test (BOT-8): Validation of a New Test in the Spanish Population During the COVID-19 Pandemic

Rojas-Lechuga MJ1,2,3, Ceballos JC1,2, Valls-Mateus M4, Mackers P5, Izquierdo-Domínguez A2,6,7, López-Chacón M1,2,3, Langdon C1,2,3, Mariño-Sánchez F8, Valero J9, Mullol J*1,2,3, Alobid I*1,2,3,7

1Rhinology Unit and Smell Clinic, Department of Otorhinolaryngology, Hospital Clinic, Universitat de Barcelona, Spain
2Clinical and Experimental Respiratory Immunoallergy, IDIBAPS, Barcelona, Spain
3CIBER Respiratory Diseases (CIBERES), Spain
4Department of Otorhinolaryngology, Hospital Universitari Son Espases, Mallorca, Spain
5Department of Otorhinolaryngology, Hospital del Mar, Barcelona, Spain
6Department of Allergology, Consorci Sanitari de Terrassa, Barcelona, Spain
7Unidad Alergo Rino, Centro Médico Teknon, Barcelona, Spain
8Rhinology and Skull Base Surgery Unit, Otorhinolaryngology Department, Hospital Ramón y Cajal, Madrid, Spain
9Departament de Fisicoquímica, Facultat de Farmàcia, Universitat de Barcelona, Spain
*These authors contributed equally as senior and corresponding authors

J Investig Allergol Clin Immunol 2022; Vol 32(4) : 291-298
doi: 10.18176/jiaci.0824

Background: Most smell tests are difficult to implement in daily clinical practice owing to their long duration. The aim of the present study was to develop and validate a short, easy-to-perform, and reusable smell test to be implemented during the COVID-19 pandemic.
Methods: The study population comprised 120 healthy adults and 195 patients with self-reported olfactory dysfunction (OD). The 8-Odorant Barcelona Olfactory Test (BOT-8) was used for detection, memory/recognition, and forced-choice identification. In addition, a rose threshold test was performed, and a visual analog scale was applied. The Smell Diskettes Olfaction Test (SDOT) was used for correlation in healthy volunteers, and the University of Pennsylvania Smell Identification Test (UPSIT) was used for patients with OD to establish cut-offs for anosmia and hyposmia. In order to take account of the COVID-19 pandemic, disposable cotton swabs with odorants were compared with the original test.
Results: In healthy persons, the mean (SD) BOT-8 score was 100% for detection, 94.5% (1.07) for memory/recognition, and 89.6% (0.86) for identification. In patients with OD, the equivalent values were 86% (32.8), 73.2% (37.9), and 77.1% (34.2), respectively. BOT-8 demonstrated good test-retest reliability, with agreement of 96.7% and a quadratic k of 0.84 (P<.001). A strong correlation was observed between BOT-8 and SDOT (r=0.67, P<.001) and UPSIT (r=0.86, P<.001). Agreement was excellent for disposable cotton swabs, with a k of 0.79 compared with the original test. The cut-off point for anosmia was ≤3 (area under the curve, 0.83; sensitivity, 0.673; specificity, 0.993).
Conclusions: BOT-8 offers an efficient and fast method for assessment of smell threshold, detection, memory, and identification in daily clinical practice. Disposable cotton swabs with odorants proved to be useful and safe during the COVID-19 pandemic.

Key words: Olfaction, Smell test, Loss of smell, Anosmia, COVID-19