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

Factors Associated With Persisting Olfactory Dysfunction After COVID-19

BACKGROUND

Fortunately, the majority of COVID-19 patients recover from olfactory dysfunction (OD) within the first couple of weeks. However, from approximately 5% up to 20% continue to suffer from OD even more than 1 year after the onset. Nonetheless, factors associated with long-lasting OD are hardly known. The aim of this study was to identify favourable and disadvantageous markers of persisting OD in COVID-19 patients.

METHODOLOGY

Sixty-six patients (46 female; mean age: 39.9 years) that suffer from OD longer than 6 months due to laboratory-confirmed SARS-CoV-2 infection have participated in this longitudinal study. Participants completed comprehensive psychophysical chemosensory tests (i.e., Sniffin' Sticks = TDI) and questionnaires twice at our department-on average 219 ± 80 (T-1) and 489 ± 89 (T-2) days after the onset of symptoms, respectively. Olfactory recovery rates were associated with demographic factors and questionnaires using linear regression analysis.

RESULTS

Patients below 40 years of age improved better (TDI: 4.1 ± 4.3 vs. 0.7 ± 5.8; p = 0.008) and achieved statistically significant higher scores (TDI: 31.5 ± 4.0 vs. 27.3 ± 6.7; p = 0.033) regarding psychophysical chemosensory tests. Furthermore, linear regression analysis revealed that parosmia was associated with worse orthonasal smell function (T-1: β = -0.346, p = 0.004; T-2: β = -0.384, p = 0.001), especially concerning identification subtest (T-1: β = -0.395, p = 0.001; T-2: β = -0.398, p < 0.001). Moreover, increasing parosmia between T-1and T-2 led to worse orthonasal olfactory function (β = -0.294, p = 0.016).

CONCLUSIONS

Older age and parosmia seem to be unfavourable factors of persisting OD in COVID-19 patients.

Determinants of persistence and recovery of chronic coronavirus disease 2019 chemosensory dysfunction

BACKGROUND

In 2% to 4% of patients, coronavirus disease 2019 (COVID-19) chemosensory dysfunction (CSD) persists beyond 6 months, accounting for up to 4 million people in the United States. The predictors of persistence and recovery require further exploration.

OBJECTIVE

We sought to define the predictors of recovery and assess the quality of CSD in registry subjects with self-reported persistent smell and taste dysfunction after COVID-19.

METHODS

COVID-19 CSD participants (n = 408) from the 4 major waves of the pandemic completed questionnaires at 4 time points between 2021 and 2023, assessing demographics, sinonasal symptoms, and self-assessed recovery. Objective measurements of smell (UPSIT) and taste (BWETT) were performed on a subcohort (n = 108).

RESULTS

In this chronic CSD cohort, the average symptom duration was 24 ± 5 months, with 70% of those who contracted COVID-19 in 2020 report ongoing dysfunction. Phantosmia and dysgeusia were most prevalent in the early waves of COVID-19, while most participants reported disrupted ability to distinguish scents and flavors as well as undulating chemosensory function. Subjects reported low incidence of subjective sinonasal symptoms but high prevalence of sleep and mood disturbance. Cigarette smoke phantosmia was predictive of persistence of CSD. Conversely, self-reported environmental allergies and hypertension were predictive of recovery, and dust mite allergies specifically were negative predictors of cigarette smoke phantosmia. Finally, no treatment resolved CSD, but nasal steroids were reported to be effective by recovered CSD subjects. Objective measures of both smell and taste were significantly reduced in patients with chronic CSD compared to controls.

CONCLUSIONS

Chronic COVID-19 CSD is a syndrome resistant to standard anti-inflammatory therapy. Preexisting environmental allergies and hypertension predict recovery, while cigarette smoke phantosmia predicts persistence.

Updated Clinical Practice Guidelines for the Diagnosis and Management of Long COVID

"Long COVID" is a term used to describe a condition when the symptoms and signs associated with coronavirus disease 2019 (COVID-19) persist for more than three months among patients infected with COVID-19; this condition has been reported globally and poses a serious public health issue. Long COVID can manifest in various forms, highlighting the need for appropriate evaluation and management by experts from various fields. However, due to the lack of clear clinical definitions, knowledge of pathophysiology, diagnostic methods, and treatment protocols, it is necessary to develop the best standard clinical guidelines based on the scientific evidence reported to date. We developed this clinical guideline for diagnosing and treating long COVID by analyzing the latest research data collected from the start of the COVID-19 pandemic until June 2023, along with the consensus of expert opinions. This guideline provides recommendations for diagnosis and treatment that can be applied in clinical practice, based on a total of 32 key questions related to patients with long COVID. The evaluation of patients with long COVID should be comprehensive, including medical history, physical examination, blood tests, imaging studies, and functional tests. To reduce the risk of developing long COVID, vaccination and antiviral treatment during the acute phase are recommended. This guideline will be revised when there is a reasonable need for updates based on the availability of new knowledge on the diagnosis and treatment of long COVID.