Phantosmia May Predict Long‐Term Measurable Olfactory Dysfunction After COVID‐19

Abstract

Objectives Persistent olfactory dysfunction (OD) after 6 months caused by SARS‐CoV‐2 infection has been reported with a variable prevalence worldwide. This study aimed to determine the prevalence of long‐term OD and identify predisposing factors. Methods A prospective cohort study was conducted on 100 adults with COVID‐19. Olfactory function was assessed with the University of Pennsylvania Smell Identification Test and a symptom survey at the onset of disease and 30 days later. Patients with persistent quantitative OD at the second assessment were reevaluated after 1 year. Demographic variables, symptoms, and the degree of smell loss were analyzed. Results Participants included 100 patients. The mean age was 42.2 ± 15.6 years, 55 (55%) were female, and 56 (56%) were outpatients. Baseline smell loss was identified in 75/100 (75%) patients, decreasing to 39/95 (40%) after 1 month, and persisting in 29 patients after 1 year. Phantosmia at baseline was the only risk factor identified for persistent OD after 1 year (relative risk 2.51; 95% confidence interval 1.53–4.12; p < 0.001). Regardless of the outcome in smell function, a significant decline in olfaction was associated with the presence of phantosmia at 1 month ( β = −12.39; 95% CI −19.82 to −4.95; p < 0.01). Conclusions SARS‐CoV‐2 (2019–2020 variants) produced a highly frequent OD that persisted in 29% of the patients after 1 year. The presence of phantosmia at baseline and 1 month was associated with a worse evolution, but phantosmia may interfere with the performance in an identification smell test. A longer follow‐up is required in these patients. Level of Evidence 2 Laryngoscope , 2022

Clinical factors influencing olfactory performance in patients with persistent COVID‐19 smell loss longer than 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. Similarly, in contrast with previous authors 11 , 12 , 13 , 14 , 39 we did not find any effect of age on smell recovery.…”

“…A meta‐analysis published in June 2022 and including articles up to October 2021 showed that female patients, subjects with greater initial severity of dysfunction or nasal congestion were less likely to recover their olfaction. 5 More recently, Leung et al 10 by using an identification test found that presence of phantosmia was associated with a worse evolution in smell recovery. In a survey conducted on 2218 COVID‐19 patients, Chudzik et al 11 found that the risk of developing persistent OD after COVID‐19 was greater in younger people with less comorbidities and a higher number of symptoms during the acute phase of COVID‐19.…”

The assessment of qualitative olfactory dysfunction in COVID-19 patients: a systematic review of tools and their content validity

“…The assessment of various aspects was also included in other studies (Schwab and Fjaeldstad, 2022 ; Fjaeldstad et al, 2023 ). For instance, in the longitudinal study by Leung et al ( 2022 ) researchers addressed the frequency, impact, and intensity of symptoms, and how these symptoms changed with time.…”

Multisensory and nutritional innovations: A narrative review of opportunities for food designers in supporting long SARS‐CoV‐2 patients

“…It is difficult to determine the exact percentage of long SARS-CoV-2 patients who experience olfactory disorders as anosmia, hyposmia, parosmia and phantosmia, as studies and data on the subject are still ongoing. However, a significant proportion of long SARS-CoV-2 patients have reported International Journal of Food Science and Technology 2023 olfactory and gustatory disturbances (Ohla et al, 2021;Leung et al, 2022). Cases of olfactory dysfunction have been reported from asymptomatic to severe, ranging from upper respiratory infections, to decreased acuity during aging, and anosmia (Whitcroft et al, 2020).…”