Proof-of-concept: SCENTinel 1.1 rapidly discriminates COVID-19-related olfactory disorders

Stellate ganglion block for treating post-COVID-19 parosmia

BACKGROUND

Post-COVID parosmia may be due to dysautonomia and sympathetic hyperresponsiveness, which can be attenuated by stellate ganglion block (SGB). This study evaluates SGB as a treatment for post-COVID olfactory dysfunction (OD).

METHODS

Retrospective case series with prospective data of patients with post-COVID OD undergoing unilateral (UL) or bilateral (BL) SGB. Patients completed Brief Smell Identification Tests (BSIT) (12 points maximum) and post-procedure surveys including parosmia severity scores on a scale of 1 (absent) to 10 (severe). Scores were compared from before treatment (pre-SGB) to after first (SGB1) or second (SGB2) treatments in overall, UL, and BL cohorts.

RESULTS

Forty-seven patients with post-COVID OD underwent SGB, including 23 UL and 24 BL. Twenty patients completed pre- and post-SGB BSITs (eight UL and 12 BL). Twenty-eight patients completed postprocedure surveys (11 UL and 17 BL). There were no differences in BSIT scores from pre-SGB to post-SGB1 or post-SGB2 for the overall (p = 0.098), UL (p = 0.168), or BL (p = 0.230) cohorts. Parosmia severity for the overall cohort improved from pre-SGB (8.82 ± 1.28) to post-SGB1 (6.79 ± 2.38) and post-SGB2 (5.41 ± 2.35), with significant differences from pre-SGB to post-SGB1 (p < 0.001) and pre-SGB to post-SGB2 (p < 0.001), but not post-SGB1 to post-SGB2 (p = 0.130). Number of parosmia triggers decreased for overall (p = 0.002), UL (p = 0.030) and BL (p = 0.024) cohorts. Quality of life (QOL) improved for all cohorts regarding food enjoyment, meal preparation, and socialization (p < 0.05).

CONCLUSION

SGB may improve subjective parosmia and QOL for patients with post-COVID OD, however it may not affect odor identification. Further placebo-controlled studies are warranted.

Using SCENTinel® to predict SARS-CoV-2 infection: insights from a community sample during dominance of Delta and Omicron variants

Introduction

Based on a large body of previous research suggesting that smell loss was a predictor of COVID-19, we investigated the ability of SCENTinel®, a newly validated rapid olfactory test that assesses odor detection, intensity, and identification, to predict SARS-CoV-2 infection in a community sample.

Methods

Between April 5, 2021, and July 5, 2022, 1,979 individuals took one SCENTinel® test, completed at least one physician-ordered SARS-CoV-2 PCR test, and endorsed a list of self-reported symptoms.

Results

Among the of SCENTinel® subtests, the self-rated odor intensity score, especially when dichotomized using a previously established threshold, was the strongest predictor of SARS-CoV-2 infection. SCENTinel® had high specificity and negative predictive value, indicating that those who passed SCENTinel® likely did not have a SARS-CoV-2 infection. Predictability of the SCENTinel® performance was stronger when the SARS-CoV-2 Delta variant was dominant rather than when the SARS-CoV-2 Omicron variant was dominant. Additionally, SCENTinel® predicted SARS-CoV-2 positivity better than using a self-reported symptom checklist alone.

Discussion

These results indicate that SCENTinel® is a rapid assessment tool that can be used for population-level screening to monitor abrupt changes in olfactory function, and to evaluate spread of viral infections like SARS-CoV-2 that often have smell loss as a symptom.

Odor dilution sorting as a clinical test of olfactory function: normative values and reliability data

Clinical assessment of an individual's sense of smell has gained prominence, but its resource-intensive nature necessitates the exploration of self-administered methods. In this study, a cohort of 68 patients with olfactory loss and 55 controls were assessed using a recently introduced olfactory test. This test involves sorting 2 odorants (eugenol and phenylethyl alcohol) in 5 dilutions according to odor intensity, with an average application time of 3.5 min. The sorting task score, calculated as the mean of Kendall's Tau between the assigned and true dilution orders and normalized to [0,1], identified a cutoff for anosmia at a score ≤ 0.7. This cutoff, which marks the 90th percentile of scores obtained with randomly ordered dilutions, had a balanced accuracy of 89% (78% to 97%) for detecting anosmia, comparable to traditional odor threshold assessments. Retest evaluations suggested a score difference of ±0.15 as a cutoff for clinically significant changes in olfactory function. In conclusion, the olfactory sorting test represents a simple, self-administered approach to the detection of anosmia or preserved olfactory function. With balanced accuracy similar to existing brief olfactory tests, this method offers a practical and user-friendly alternative for screening anosmia, addressing the need for resource-efficient assessments in clinical settings.

More spice, less salt: How capsaicin affects liking for and perceived saltiness of foods in people with smell loss

People who lose their sense of smell self-report consuming more salt to compensate for a lack of flavor and enhance eating enjoyment. However, this may contribute to excess sodium intake. Capsaicin may help increase salt taste intensity and eating enjoyment in people with smell loss, but this has not been studied in this population. The purpose of this study was to determine 1) whether salt intake in those with smell loss differs from population averages, 2) whether capsaicin increases flavor and salt taste intensity, and 3) if adding spice to foods increases liking in individuals with smell loss. Thirty-three participants 18-65 years old with confirmed smell loss for at least 12 weeks completed two sets of replicate test sessions (four total). In two sessions participants rated overall flavor intensity, taste qualities' intensities, spicy intensity, and liking for model tomato soups with low or regular sodium content and three levels of capsaicin (none, low, or moderate). In the other two sessions, participants rated the same sensory attributes for model food samples with three levels of added spice (none, low, or moderate). 24-hour urine samples were collected to determine sodium intake. Results indicate that although sodium intake is higher than recommended (<2300 mg/day) in those with smell loss (2893 ± 258 mg/day), they do not consume more sodium than population averages (3039 ± 100 mg/day; p = 0.3). Adding low and moderate amounts of capsaicin to a model tomato soup increased the intensity of overall flavor (p < 0.001) and saltiness (p = 0.004) compared to a model tomato soup without capsaicin. However, capsaicin's effect on liking differed by food type. Thus, capsaicin can improve flavor, salt taste intensity, and eating enjoyment in people with smell loss.

Patient Insights into the Diagnosis of Smell and Taste Disorders in the United States

OBJECTIVES

Diagnosis of smell/taste dysfunction is necessary for appropriate medical care. This study examines factors affecting testing and diagnosis of smell/taste disorders .

METHODS

The online USA Smell and Taste Patient Survey was made available to US patients with smell/taste disorders between April 6-20, 2022. 4,728 respondents were included.

RESULTS

1,791 (38%) patients reported a documented diagnosis. Patients most often saw family practitioners (34%), otolaryngologists (20%), and Taste/Smell clinics (6%) for smell/taste dysfunction. 64% of patients who went to Taste/Smell clinics received smell testing, followed by 39% of patients who saw otolaryngologists, and 31% of patients who saw family practitioners. Factors associated with increased odds of diagnosis included age (25-39 years (OR 2.97, 95% CI [2.25, 3.95]), 40-60 (OR 3.3, 95% CI [2.56, 4.52]), and >60 (OR 4.25, 95% CI [3.21, 5.67]) vs. 18-24 years), male gender (OR 1.26, 95% CI [1.07, 1.48]), insurance status (private (OR 1.61, 95% CI [1.15, 2.30]) or public (OR 2.03, 95% CI [1.42, 2.95]) vs. uninsured), perception of their family practitioner to be knowledgeable (OR 2.12, 95% CI [1.16, 3.90]), otolaryngologic evaluation (OR 6.17, 95% CI [5.16, 7.38]), and psychophysical smell testing (OR 1.77, 95% CI [1.42, 2.22]).

CONCLUSION

Psychophysical testing, otolaryngologic evaluation, patient assessment of family practitioner knowledge level, insurance, age, and gender are significant factors in obtaining smell/taste dysfunction diagnosis. This study identifies barriers to diagnosis including lack of insurance or access to specialist evaluation and highlights the importance of educating family practitioners in diagnosis and management of patients with smell/taste disorders.

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

Background

There is a lack of overview of the tools used to assess qualitative olfactory dysfunction, including parosmia and phantosmia, following COVID-19 illness. This could have an impact on the diagnosis and treatment offered to patients. Additionally, the formulations of symptoms are inconsistent and often unclear, and consensus around the wording of questions and responses is needed.

Aim of study

The aim of this systematic review is to provide an overview of tools used to assess qualitative olfactory dysfunction after COVID-19, in addition to addressing the content validity (i.e., item and response formulations) of these tools.

Methods

MEDLINE, Web of Science, and EMBASE were searched 5th of August 2022 and updated on the 25th of April 2023 to identify studies that assess qualitative olfactory dysfunction in COVID-19 patients. Primary outcomes were the tool used (i.e., questionnaire or objective test) and item and response formulations. Secondary outcomes included psychometric properties, study design, and demographic variables.

Results

The assessment of qualitative olfactory dysfunction is characterized by heterogeneity, inconsistency, and lack of validated tools to determine the presence and degree of symptoms. Several tools with overlapping and distinct features were identified in this review, of which some were thorough and detailed, while others were merely assessing the presence of symptoms as a binary measure. Item and response formulations are also inconsistent and often used interchangeably, which may lead to confusion, incorrect diagnoses, and inappropriate methods for solving the problem.

Conclusions

There is an unmet need for a reliable and validated tool for assessing qualitative olfactory dysfunction, preferably one that also captures quantitative olfactory issues (i.e., loss of smell), to ensure time-effective and specific assessment of the ability to smell. A consensus around the formulation of items and response options is also important to increase the understanding of the problem, both for clinicians, researchers, and the patient, and ultimately to provide the appropriate diagnosis and treatment.

Registration and protocol

The URL is https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=351621. A preregistered protocol was submitted and accepted (12.09.22) in the International prospective register of systematic reviews (PROSPERO) with the registration number CRD42022351621.

More spice, less salt: how capsaicin affects liking for and perceived saltiness of foods in people with smell loss

People who lose their sense of smell self-report consuming more salt to compensate for a lack of flavor and enhance eating enjoyment. However, this can contribute to excess sodium intake and a poor diet. Capsaicin may help increase salt taste intensity and eating enjoyment in this population, but this has not been studied. The purpose of this study was to determine 1) whether salt intake in those with smell loss differs from population averages, 2) whether capsaicin increases flavor and salt taste intensity, and 3) if adding spice to foods increases food liking in individuals with smell loss. Participants 18-65 years old with confirmed partial or total smell loss for at least 12 weeks completed two sets of replicate test sessions (four total). In two sessions participants rated overall flavor intensity, taste qualities' intensities, spicy intensity, and liking for model tomato soups with low or regular sodium content and three levels of capsaicin (none, low, or moderate). In the other two sessions, participants rated the same sensory attributes for model food samples with three levels of added spice (none, low, or moderate). 24-hour urine samples were also collected to determine sodium intake. Results indicate that although sodium intake is higher than recommended in those with smell loss (2893 ± 258 mg/day), they do not consume more sodium than population averages. Adding low and moderate amounts of capsaicin to a model tomato soup increased the intensity of overall flavor and saltiness compared to a model tomato soup without capsaicin. However, the effect of capsaicin on liking differed by food type. In conclusion, the addition of capsaicin can improve flavor, salt taste intensity, and eating enjoyment in people with smell loss.

Low to moderate genetic influences on the rapid smell test SCENTinel™

SCENTinel™ - a rapid, inexpensive smell test that measures odor detection, intensity, identification, and pleasantness - was developed for population-wide screening of smell function. SCENTinel™ was previously found to screen for multiple types of smell disorders. However, the effect of genetic variability on SCENTinel™ test performance is unknown, which could affect the test's validity. This study assessed performance of SCENTinel™ in a large group of individuals with a normal sense of smell to determine the test-retest reliability and the heritability of SCENTinel™ test performance. One thousand participants (36 [IQR 26-52] years old, 72% female, 80% white) completed a SCENTinel™ test at the 2021 and 2022 Twins Days Festivals in Twinsburg, OH, and 118 of those completed a SCENTinel™ test on each of the festival's two days. Participants comprised 55% percent monozygotic twins, 13% dizygotic twins, 0.4% triplets, and 36% singletons. We found that 97% of participants passed the SCENTinel™ test. Test-retest reliability ranged from 0.57 to 0.71 for SCENTinel™ subtests. Broad-sense heritability, based on 246 monozygotic and 62 dizygotic twin dyads, was low for odor intensity (r=0.03) and moderate for odor pleasantness (r=0.4). Together, this study suggests that SCENTinel™ is a reliable smell test with only moderate heritability effects, which further supports its utility for population-wide screening for smell function.