Long-lasting olfactory dysfunction in COVID-19 patients

Abstract

Objectives Olfactory dysfunction (OD) is a common symptom of Coronavirus Disease 2019 (COVID-19). Although many patients have been reported to regain olfactory function within the first month, long-term observation reports vary. Therefore, we aimed to assess the course of chemosensory function in patients diagnosed with COVID-19 within 3–15 months after the infection. Methods One hundred and two patients (71 females and 31 males; mean age 38.8 years) diagnosed with laboratory-confirmed COVID-19 and subjective OD participated in this single-center study 111–457 days after onset of OD. Patients first performed chemosensory tests at home, followed by psychophysical testing (Sniffin’ Sticks (TDI), 27-item Candy Smell Test (CST), Taste Strips Test (TST)) in the clinic. Questionnaires regarding importance of olfaction (IOQ) and olfactory-specific quality of life (QOD) were applied at both timepoints. Results After a mean 216 days (SD 73; range 111–457) between OD onset and follow-up testing, the mean Sniffin’ Sticks (TDI) score was 27.1 points (SD 5.8; range 4.25–38.5): 4.0% were anosmic, 72.5% hyposmic, and 23.5% normosmic. At follow-up testing, 73.5% of patients reported improvement, 5.9% deterioration, and 20.6% no change in OD. Moreover, full recovery of self-perceived smell, flavor, and taste was not observed. According to questionnaires, the individual importance of smell did not change, but participants showed improvement in OD-related quality of life (p < 0.001) and had increased parosmia scores (p = 0.014) at follow-up. Conclusion Our results show that long-lasting OD after SARS-CoV-2 infection is a common symptom. The majority of patients had OD in the range of hyposmia, which was confirmed by comprehensive smell tests.

Analysis of Prevalence and Predictive Factors of Long-Lasting Olfactory and Gustatory Dysfunction in COVID-19 Patients

“…Furthermore, it is noteworthy that among the patients who self-reported a normal sense of smell, 75% exhibited some degree of alteration in UPSIT. A well-known inverse correlation between UPSIT scores and age [ 56 ] was found in our study ( r = −0.35, p = 0.0033). As expected, although higher UPSIT scores were found in patients who reported lower smell VAS values, the correlation between UPSIT and VAS scores was only moderate ( r = −0.36, p = 0.003) ( Figure 2 ), which agrees with previous olfactometry studies conducted in the European population [ 10 , 26 , 56 ].…”

“…The majority of patients (82.6%) showed an altered smell function in the UPSIT test, a considerably higher proportion than the 41.1% found in [ 55 ]. Other groups that quantified the smell through different olfactometry tests, such as the Sniffin’ Sticks test and the Brief Smell Identification test, showed rates for hyposmia from 25.4% to 72.5% [ 23 , 56 ] and 76% [ 57 ], respectively, compared with the 75.3% obtained in our study. The prevalence of anosmia in our study (7.2%) ( Table 9 ) was also higher than rates previously published between 0% and 4% [ 55 , 56 ].…”

“…Other groups that quantified the smell through different olfactometry tests, such as the Sniffin’ Sticks test and the Brief Smell Identification test, showed rates for hyposmia from 25.4% to 72.5% [ 23 , 56 ] and 76% [ 57 ], respectively, compared with the 75.3% obtained in our study. The prevalence of anosmia in our study (7.2%) ( Table 9 ) was also higher than rates previously published between 0% and 4% [ 55 , 56 ]. Furthermore, it is noteworthy that among the patients who self-reported a normal sense of smell, 75% exhibited some degree of alteration in UPSIT.…”

High prevalence of long-term olfactory disorders in healthcare workers after COVID-19: a case-control study

“…Olfactory dysfunction (OD) is a key symptom of COVID-19 with the prevalence of anosmia due to COVID-19 reported as 50% with an additional 10-20% reporting hyposmia 1 ; a significant portion also report parosmia (olfactory distortion). Hence, at some point of the disease, nearly 70% experience either partial or total loss or distortion of their sense of smell 2 . Because OD is associated with a range of aversive health effects, such as depression and weight gain, the prevalence of COVID-19-related OD, and whether its transient or persistent, are vital public health questions.…”

Distinct smell and taste disorder phenotype of post-acute COVID-19 sequelae

“…Although literature suggests resolution of OD within 2-3 weeks in most patients (17), OD may persist up to 6 months in 5-11% of patients (11,(18)(19)(20). Consequently, it represents an important post-acute sequelae, with a disabling character for certain patients due to its effect on quality of life, daily functioning and professional activity (20)(21)(22)(23). Characterization of COVID-19 recovery patterns is crucial to identify patients at risk of persistent OD who may profit from targeted therapy such as olfactory training .…”