Persisting Chemosensory Impairments in 366 Healthcare Workers Following COVID-19: An 11-Month Follow-up

Abstract

Background and Objectives: Olfactory and gustatory dysfunctions (OD, GD) are prevalent symptoms following COVID-19 and persist in 6%-44% of individuals in the first months after the infection. As only few reports have described their prognosis more than 6 months later, the main objective of this study was to assess the prevalence of OD and GD 11 months after COVID-19. We also aimed to determine test-retest reliability of subjective chemosensory ratings for the follow-up of chemosensory sensitivity, as this measure is often used for remote follow-up. Methods: Inclusion criteria included a PCR-confirmed SARS-CoV-2 infection; exclusion criteria were the presence of other respiratory infections and chronic sinusitis. To assess whether OD and GD had changed compared to pre-pandemic levels, we designed an observational study and distributed an online questionnaire assessing quantitative chemosensory function to healthcare workers 5 and 11 months after COVID-19. Specifically, we assessed olfaction, gustation, and trigeminal sensitivity (10-point visual analog scale) and function (4-point Likert scale) separately. We further assessed clinically relevant OD using the Chemosensory Perception Test, a psychophysical test designed to provide a reliable remote olfactory evaluation. Qualitative chemosensory dysfunction was also assessed. Results: We included a total of 366 participants (mean age of 44.8 years old (SD: 11.7)). They completed the last online questionnaire 10.6 months (SD: 0.7) after the onset of COVID-19 symptoms. Of all participants, 307 (83.9%) and 301 (82.2%) individuals retrospectively reported lower olfactory or gustatory sensitivity during the acute phase of COVID-19. Eleven months later, 184 (50.3%) and 163 (44.5%) indicated reduced chemosensory sensitivity, 32.2% reported impairment of olfactory function while 24.9% exhibited clinically relevant OD. Three variables predicted OD at follow-up, namely chest pain and GD during COVID-19 and presence of phantosmia at 5 months. Olfactory sensitivity ratings had a high test-retest reliability (intraclass correlation coefficient: 0.818 (95% CI: 0.760 - 0.860)) Discussion: This study suggests that chemosensory dysfunctions persist in a third of COVID-19 patients 11 months after COVID-19. Subjective measures have a high test-retest reliability and thus can be used to monitor post-COVID-19 OD. OD appears to be a common long-term symptom of COVID-19 important to consider when treating patients.

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

“…Upon infection, these cells degenerate which disturbs the local environment which, crucially, results in cell death of olfactory receptor neurons and associated olfactory dysfunction (Cooper et al, 2020; Xydakis et al, 2021). The olfactory system demonstrates, however, a very good ability to regenerate (Reden et al, 2006) which might explain why most of SARS-CoV-2 infected individuals regain olfactory abilities within weeks following the acute phase (Bussiere et al, 2021; Bussiere et al, 2022). It is not yet clear why some individuals do not completely regain their olfactory abilities.…”

“…Olfactory dysfunction is the most specific symptom of acute COVID-19 (Gerkin et al, 2021; Rudberg et al, 2020) and smell abilities are heavily impacted by COVID-19 (Parma et al, 2020). Olfactory function recovers in many patients after olfactory dysfunction in the acute phase of COVID-19 (Bussiere et al, 2022). However, a non-negligeable proportion of patients exhibits chronic olfactory dysfunction after COVID-19 (McWilliams et al, 2022).…”

“…However, a non-negligeable proportion of patients exhibits chronic olfactory dysfunction after COVID-19 (McWilliams et al, 2022). Estimations of the prevalence of olfactory dysfunction more than 6 months after an infection by SARS-CoV-2 – a threshold for chronicity of olfactory dysfunction – vary widely (Boscolo-Rizzo et al, 2022; Bussiere et al, 2021; Bussiere et al, 2022; Capelli & Gatti, 2021; Hopkins et al, 2021; Lechien et al, 2021; Ohla et al, 2022). Critically, a recent assessment of olfactory dysfunction based on subjective reports only, suggests that two years after contracting COVID-19, a staggering 61% still experience olfactory dysfunction (McWilliams et al, 2022).…”

Sociodemographic Characteristics and Comorbidities of Patients With Long COVID and Persistent Olfactory Dysfunction

“…The data are being collected as part of the follow-up research of this cohort and will be published in the future because the presence of these olfactory dysfunctions may be associated with the recovery of sense of smell. 63,64 The absence of formal data regarding previous clinical history and the acute phase of COVID-19 is a potential confounding factor, which was minimized by carefully using an anamnesis form and specialized consultation with neurologists and otolaryngologists. Future studies should continue the monitoring of this population, prioritizing interdisciplinary research in clinical, epidemiologic, and basic science, such as genetics and immunology.…”

Prevalence and 24‐month recovery of olfactory dysfunction in COVID‐19 patients: A multicentre prospective study

“…Although most patients recover the sense of smell within a few weeks, several authors have reported a significant rate of long‐term OD [ 8 , 9 , 10 ]. Only a few authors have investigated the prevalence of OD 1 year after infection with objective methods [ 11 , 12 , 13 ], and there are no studies with 2‐year follow‐up. Long follow‐up is essential to obtain a reliable estimate of the prevalence of persistent OD.…”