Comparison of prevalence and evolution of COVID-19 olfactory disorders in patients infected by D614 (wild) and B.1.1.7. Alpha variant: a brief report

Abstract

Objectives To investigate the prevalence and the evolution of olfactory disorders (OD) related to coronavirus disease 2019 (COVID-19) in patients infected during the first and the second European waves. Methods From March 2020 to October 2020, COVID-19 patients with OD were recruited and followed over the 12-month post-infection. The following data were collected: demographic, treatments, vaccination status, and olfactory function. Olfaction was assessed with the Olfactory Disorder Questionnaire (ODQ), and threshold, discrimination, and identification (TDI) test. Outcomes were compared between patients of the first wave (group 1: wild/D614G virus) and the second wave (group 2: B.1.1.7. Alpha variant) at 1-, 3- and 12-month post-infection. Results Sixty patients completed the evaluations accounting for 33 and 27 patients in group 1 and 2, respectively. The 1-month TDI score (23.7 ± 5.3) was significantly lower in group 2 compared to group 1 (29.8 ± 8.7; p = 0.017). Proportion of normosmic patients at 1-month post-infection was significantly higher in group 1 compared to group 2 ( p = 0.009). TDI scores only significantly increased from 1- to 3-month post-infection in anosmic and hyposmic patients. Focusing on There was a negative association between the 1-month ODQ and the 1-month TDI ( r s = − 0.493; p = 0.012). ODQ was a significant predictor of TDI scores at 3- and 12-month post-infection. The 12-month prevalence of parosmia was 60.6% in group 1 and 42.4% in group 2, respectively. There was no significant influence of oral corticosteroid treatment, adherence to an olfactory training and vaccination status on the olfactory outcomes. Conclusions Patients of the second wave (Alpha B.1.1.7. variant) reported significant higher proportion of psychophysical test abnormalities at 1-month post-infection than patients infected during the first wave (D614G virus).

Clinical factors influencing olfactory performance in patients with persistent COVID‐19 smell loss longer than 1 year

“…Even though this could have been caused by a sample bias in our study, our finding corroborates previous results from Akbari and colleagues 39 who found significant better identification scores in smokers but also previous studies 41,42 which reported that COVID‐19‐related OD is less frequent in patients with a smoking habit. Prevalence of parosmia in our population (80%) was higher when compared to previous studies, although this varies widely across different studies in the literature and reported to be between 43% at 6 months and 70.9% when evaluated at 1 year 43–46 . A higher prevalence of parosmia in our group of patients could be explained either by a longer OD in our population (1.4 years) or by the fact that only patients with a self‐reported long‐term OD were referred to our long‐COVID smell clinic and included in the study.…”

“…Prevalence of parosmia in our population (80%) was higher when compared to previous studies, although this varies widely across different studies in the literature and reported to be between 43% at 6 months and 70.9% when evaluated at 1 year. 43 , 44 , 45 , 46 A higher prevalence of parosmia in our group of patients could be explained either by a longer OD in our population (1.4 years) or by the fact that only patients with a self‐reported long‐term OD were referred to our long‐COVID smell clinic and included in the study. Although past studies have reported a possible influence of parosmia 14 , 15 and phantosmia 10 on smell recovery our analysis did not confirm that.…”

Subjective Perception of Recovery and Measured Olfactory Function in COVID-19 Patients

“…Parosmia is frequent in COVID-19-associated olfactory loss. At around 1 year after COVID-19 infection, the prevalence of parosmia still ranges between 23 and 61% in the literature [ 20 , 21 , 22 ]. It is associated with difficulties in odor identification that typically are not paralleled by major changes in odor thresholds [ 23 ].…”

Comparison of Patient Characteristics and Olfactory Sensitivity for Trigger Odorants in Parosmia and Phantosmia

“…16 Since 2020, clinicians have increasingly encountered patients with qualOD due to its association with COVID-19. 8,10,[16][17][18][19][20][21][22][23][24][25][26] Despite the surge in cases, there remains limited understanding of the pathophysiology of qualOD, 8 but it is suspected to arise from a complex interaction between peripheral and central mechanisms. 8,9,20 Parosmia typically occurs after quantitative OD, among younger women 20 after post-infectious olfactory loss 27 or head trauma, 27 whereas phantosmia may occur in idiopathic OD, with tumors, or neuropsychiatric conditions.…”

“…Despite its generally unpleasant nature, some studies have shown parosmia as an indicator of recovery of OD particularly in cases of post‐viral olfactory dysfunction (PVOD), 5,12–15 whereas another showed a lower rate of recovery among those with parosmia 16 . Since 2020, clinicians have increasingly encountered patients with qualOD due to its association with COVID‐19 8,10,16–26 . Despite the surge in cases, there remains limited understanding of the pathophysiology of qualOD, 8 but it is suspected to arise from a complex interaction between peripheral and central mechanisms 8,9,20 …”