Diagnostic Value of Butanol Threshold Test in COVID-19 Related Olfactory Dysfunction

Olfactory and taste dysfunction has been reported as a specific, preliminary symptom in COVID-19, but a few comparative studies with quantitative tests are reported. In this study, we aimed to compare the butanol olfactory threshold values between COVID-19 patients and healthy volunteers.A cross-sectional study was designed. A total of 53 patients were included in the COVID-19 group and the control group. The definitive diagnosis of COVID-19 was made with reverse-transcription polymerase chain reaction (RT-PCR) test. Frequency of odor and taste dysfunction and other head and neck system-specific and other symptoms were recorded. Afterward, olfactory threshold values determined according to Connecticut Chemosensory Clinical Research Center (CCCRC) test principle for study groups. 21 patients included in the COVID-19 group and 32 patients in the control group. Symptom onset time was 7.1 ± 3.1 (min: 3, max: 14) days for COVID-19 patients. The most common symptom in the otolaryngology system was olfactory dysfunction (n = 15, 71.4%). The butanol olfactory threshold value was determined as an average of 4.4 ± 1.9 in the COVID-19 group and 6.4 ± 0.8 in the control group (p < 0.001, 95% CI 2.9–1.0). The sensitivity of the butanol threshold test for COVID-19 related olfactory dysfunction was 80.0% and the specificity was 66.6%. For differential, early and initial, diagnosis of COVID-19, complaint of the smell dysfunctions, and impairment butanol threshold may be a distinctive indicator.