Quantitative evaluation and progress of olfactory dysfunction in COVID-19

Purpose Since many different rates have been reported in the literature and the studies conducted are mostly based on the patient anamnesis, it was aimed to analyze the olfactory dysfunction in Coronavirus Disease 2019 (COVID-19) quantitatively and to reveal its progress by time. Methods Patients who described new-onset olfactory dysfunction, who were treated in the COVID-19 departments of our hospital and whose PCR tests demonstrated SARS-CoV-2 presence were included in the study and they were investigated prospectively. Clinical information of all the patients was taken and the levels of olfactory function were detected using the Brief Smell Identification Test (BSIT). Scores equal to or below 8 are considered as olfactory dysfunction. Patients who were followed up for 3 months were reevaluated with the BSIT test at the end of the third month and the progression of the symptom was investigated. Results The mean BSIT test score of the 42 patients (23 female patients, 19 male patients, mean age: 41.2 +/- 14.6) was 5.2 +/- 2.2. There was severe olfactory dysfunction in 16.7% of the patients (0-2 points), moderate olfactory dysfunction in 31% (3-5 points), and mild olfactory dysfunction in 52.4% (6-8 points). After a follow-up for 3 months, full recovery was observed in 36 patients (85.7%) and the mean test score rose to 9.9 +/- 1.8. Although olfactory dysfunction persisted in 6 patients, an elevation in test scores was noted. Olfactory dysfunction was the first symptom in 17 patients (40%) and the other symptoms occurred after 2 days (1-6) on average. Conclusion We investigated olfactory dysfunction caused by COVID-19 using BSIT, and found a high rate of moderate-mild level symptoms with a high level of recovery in the 3-month follow-up. The finding revealing that olfactory dysfunction was the first symptom in 40% of the patients suggests the importance of inquiry on olfactory functions for the early diagnosis of the disease.