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: ß = -0.346, p = 0.004; T-2: ß = -0.384, p = 0.001), especially concerning identification subtest (T-1: ß = -0.395, p = 0.001; T-2: ß = -0.398, p < 0.001). Moreover, increasing parosmia between T-1and T-2 led to worse orthonasal olfactory function (ß = -0.294, p = 0.016). CONCLUSIONS: Older age and parosmia seem to be unfavourable factors of persisting OD in COVID-19 patients.

The olfactory diary: Tracking awareness and consciousness of the sense of smell throughout the day.

Objectives: The aim of the present study was to follow the daily course of patients with olfactory dysfunction and healthy controls and to assess (i) how many times a day, (ii) at which time, and (iii) in which aspect of daily life participants are conscious about their sense of smell. Methods: In this longitudinal study, 49 patients with smell loss and 30 healthy participants were enrolled. Olfactory function was assessed using the Sniffin' Sticks. All participants received paper diaries designed for a 14-day period, featuring 12 rows representing 12 daily hours and six columns for various daily life aspects. They were instructed to mark their awareness of smell by indicating the relevant row and column in the diary. Following the return of the diaries, a second olfactory test was conducted within the patient group. Results: On average, patients were consciously aware of their sense of smell around 8 times daily, while healthy participants noted it about 6.5 times a day. Both groups primarily focused on their sense of smell during activities related to "eating," followed by considerations in "social life" and "personal hygiene." Interestingly, distinct patterns emerged: patients peaked in awareness at 8 a.m. and 7 p.m., whereas healthy individuals showed peaks at 6 a.m., 12 p.m., and 7 p.m. Despite regular diary use, we observed no improvement in patients' olfactory function or related quality of life. Conclusion: The olfactory diary is a valuable tool unveiling individual smell awareness patterns in patients with smell loss, aiding in counseling and patient management. Level of Evidence: 4.

Eating behavior in patients with smell loss.

Background: The objective of this study was to determine how clinical characteristics and validated quality of life (QoL)-measures are associated with eating behavior in patients with olfactory dysfunction (OD). Methods: For this cross-sectional study, 150 OD patients of different causes were retrospectively recruited. Olfactory function was measured using the Sniffin' Sticks (TDI), while olfactory-related QoL was evaluated with the Questionnaire of OD negative and positive statements (QOD-NS and QOD-PS). The importance of olfaction was measured using the Importance of Olfaction Questionnaire (IOQ). The Dutch Eating Behavior Questionnaire (DEBQ) assessed eating behavior based on emotional, external, and restrained eating. Associations were sought between eating behavior metrics (as dependent variables) with clinical characteristics and olfactory-related outcome measures. Results: Emotional, external, and restrained eating behavior deviating from normative standards were reported in 54%, 71.3%, and 68% of patients, respectively. Multivariate regression modeling revealed that emotional eating was associated with age (ß = -0.227, p = 0.032), the body mass index (BMI, ß = 0.253, p = 0.005), the TDI (ß = 0.190, p = 0.046), and the QOD-NS (ß = 0.203, p = 0.049). External eating was associated with OD duration (ß = 0.291, p = 0.005), the TDI (ß = 0.225, p = 0.018), the QOD-PS (ß = -0.282, p = 0.008), and the IOQ (ß = 0.277, p = 0.004). Restrained eating was associated with age (ß = 0.216, p = 0.033), the BMI (ß = 0.257, p = 0.003), male gender (ß = -0.263, p = 0.002), and the IOQ (ß = 0.332, p < 0.001). Conclusion: Clinical characteristics and olfactory outcome measures differentially impact eating styles in OD patients. Our study's results highlight the importance of considering unfavorable changes in eating behavior during clinical counseling.

Pediatric olfactory home testing using regular household items: A cross-over validation study.

OBJECTIVE: To develop an olfactory test that can be conducted by an untrained person using common household items and to introduce a German version of the Chemosensory Pleasure Scale for Children (CPS-C(de)). METHODOLOGY: This olfactory home test was developed in phases including evaluation of odors for suitability in a home setting. Parents of 50 children (ages 6-17) were then equipped with instruction manuals and participants were tested twice in a cross-over design. A validated pediatric olfactory test (the Universal Sniff test (U-Sniff)) served as the comparative gold standard. Additionally, a Chinese-English-German "back-and-forth" translation was conducted to establish the CPS-C(de) and was tested for empirical validity. RESULTS: Fourteen items were tested for feasibility, and all were identified on a sufficient rate (≥66%, mean ±â€¯SD of 93.3% ±â€¯9.5%). Bland Altman Plot analysis between home testing and the U-Sniff test was nearly identical (bias = 0.04). CPS-C(de) showed similar results to the original Chinese version and a moderate correlation was found between CPS-C(de) scores and Body Mass Index of children (r30 = -0.527, p = 0.003). CONCLUSIONS: Remote olfactory testing in children using household items is feasible. The CPS-C(de) may be of value for future olfactory studies.

Depression Symptoms and Olfactory-related Quality of Life.

OBJECTIVES: Patients with olfactory dysfunction (OD) frequently report symptoms of depression. The objective of this study was to determine how clinical characteristics and olfactory-related quality of life (QoL) measures associate with the likelihood for major depressive disorders (MDDs). METHODS: A total of 192 OD patients were included. Olfactory function was measured using all three subtests of the Sniffn' Sticks test. Olfactory-related quality of life (QoL) was evaluated using the Questionnaires of Olfactory Dysfunction (QOD)-negative (NS) and -positive statement (PS). The likelihood for MDD was assessed using the Patients Health Questionnaire-2 (PHQ-2). Demographics and disease-specific variables (etiology and duration of OD) were collected. Univariate and multivariable analyses were used to associate disease-specific variables and the QOD with the outcome of the PHQ-2. Additionally, the predictive ability of the QOD-NS to predict depressive symptoms was calculated. RESULTS: In univariate analysis, COVID-19 related smell loss, the QOD-NS, and the QOD-PS were significantly associated with the PHQ-2. In multivariable analyses adjusting for QoL measures, the QOD-NS (ß = 0.532, p < 0.001) and sinonasal OD (compared with postinfectious OD) were significantly associated with the PHQ-2 (ß = 0.146, p = 0.047). When omitting QoL measures from multivariable analyses, only COVID-19 related OD (compared with postinfectious OD) was significantly associated with the PHQ-2 (ß = 0.287, p = 0.009). A QOD-NS score > 20.5 had 70.13% sensitivity and 76.32% specificity for detecting symptoms of depression. CONCLUSION: Our results suggest that COVID-19 related OD might be associated with a higher likelihood for MDD. Furthermore, we showed that the QOD-NS score might be helpful to predict symptoms of depression in OD patients. LEVEL OF EVIDENCE: 4 Laryngoscope, 132:1829-1834, 2022.

Retronasal olfactory testing in early diagnosed and suspected COVID-19 patients: a 7-week follow-up study.

OBJECTIVES: Olfactory dysfunction (OD) constitutes a major symptom in Coronavirus Disease 2019 (COVID-19). Yet, most data on smell loss rely on the evaluation of orthonasal olfactory performance. Therefore, we aimed to assess retronasal olfactory function (ROF) over a period of several weeks in proven and suspected COVID-19 patients. METHODS: One hundred and one subjects with suspected or laboratory-proven COVID-19 participated in this study. In patients with OD no longer than 4 weeks after initial symptom onset, ROF was measured with the 7-item Candy Smell Test ten times over 7 weeks. RESULTS: Olfactory function was decreased in the investigated patients and remained decreased over the course of 7 weeks. One-way repeated-measures ANOVA revealed no significant difference of ROF between different measurement time points. However, self-assessment of smell and flavour improved significantly (p = 0.013 and p = 0.043), but did not show complete recovery. CONCLUSION: The current investigation revealed significant improvements in subjective smell and flavour perception over the course of 7 weeks in proven and suspected COVID-19 patients suffering from acute OD. However, objectively measured ROF based on a screening test revealed no improvements within the same time period.

Olfactory-related Quality of Life Adjustments in Smell Loss during the Coronavirus-19 Pandemic.

BACKGROUND: Previous studies provided the first evidence that the importance of olfaction decreases with the duration of olfactory dysfunction (OD). OBJECTIVE: To evaluate differences in olfactory-related quality of life (QoL) between patients with new-onset and persistent smell loss (>4 weeks) during the coronavirus-19 (COVID-19) pandemic and patients with persistent postinfectious OD (PIOD) that were recruited before the pandemic. METHODS: This was a retrospective study that included 149 patients with self-reported OD. The olfactory-related QoL was measured using the questionnaire of OD (QOD). The QOD measures the degree to which patients (i) adjust and cope with smell loss (QOD-positive statement [QOD-PS]), (ii) suffer from distorted odor perceptions (QOD-parosmia [QOD-PAR]), and (iii) suffer from smell loss in general (QOD-negative statement [QOD-NS]). Self-perceived chemosensory function, demographics, olfactory function, and duration of smell loss were evaluated. Analyses of variance were used to depict differences in QoL-outcomes between different OD groups. RESULTS: All patients included during the COVID-19 pandemic reported an extensive loss of chemosensory functions of smell, taste, and flavor perception. Psychophysical retronasal screening testing showed olfactory impairments in more than half of these patients. One-way analysis of variance and posthoc tests revealed that the QOD-NS was significantly higher in the new-onset OD group than the PIOD group. At the same time, the QOD-PS score was significantly higher in the PIOD and the persistent COVID-19 OD group than in the new-onset OD group. CONCLUSION: We showed that patients with persistent OD experienced better olfactory-related adjustment and lower QoL-impairment scores than those with recent-onset smell loss, suggesting that the olfactory-related QoL might change as a function of time after symptom onset.

Long-lasting olfactory dysfunction in COVID-19 patients.

OBJECTIVES: Olfactory dysfunction (OD) is a common symptom of Coronavirus Disease 2019 (COVID-19). Although many patients have been reported to regain olfactory function within the first month, long-term observation reports vary. Therefore, we aimed to assess the course of chemosensory function in patients diagnosed with COVID-19 within 3-15 months after the infection. METHODS: One hundred and two patients (71 females and 31 males; mean age 38.8 years) diagnosed with laboratory-confirmed COVID-19 and subjective OD participated in this single-center study 111-457 days after onset of OD. Patients first performed chemosensory tests at home, followed by psychophysical testing (Sniffin' Sticks (TDI), 27-item Candy Smell Test (CST), Taste Strips Test (TST)) in the clinic. Questionnaires regarding importance of olfaction (IOQ) and olfactory-specific quality of life (QOD) were applied at both timepoints. RESULTS: After a mean 216 days (SD 73; range 111-457) between OD onset and follow-up testing, the mean Sniffin' Sticks (TDI) score was 27.1 points (SD 5.8; range 4.25-38.5): 4.0% were anosmic, 72.5% hyposmic, and 23.5% normosmic. At follow-up testing, 73.5% of patients reported improvement, 5.9% deterioration, and 20.6% no change in OD. Moreover, full recovery of self-perceived smell, flavor, and taste was not observed. According to questionnaires, the individual importance of smell did not change, but participants showed improvement in OD-related quality of life (p < 0.001) and had increased parosmia scores (p = 0.014) at follow-up. CONCLUSION: Our results show that long-lasting OD after SARS-CoV-2 infection is a common symptom. The majority of patients had OD in the range of hyposmia, which was confirmed by comprehensive smell tests.

Bitter Taste Disrupts Spatial Discrimination of Piperine-Evoked Burning Sensations: A Pilot Study.

This study aimed to investigate the perceptual similarity between piperine-induced burning sensations and bitter taste using piperine-impregnated taste strips (PTS). This pilot study included 42 healthy participants. PTS of six ascending concentrations (1 mg, 5 mg, 10 mg, 15 mg, 20 mg, and 25 mg piperine/dL 96% ethanol) were presented at the anterior tongue, and participants rated perceived intensity and duration. Then, participants performed a spatial discrimination task in which they had to report which of the two strips presented to the anterior tongue contained an irritating stimulus when one strip was always a PTS while the other strip was impregnated with either a single taste quality (sweet or bitter) or a blank strip. Repeated measures one-way ANOVA revealed that burning sensations of higher concentrated PTS were perceived more intense and more prolonged compared to lower concentrated PTS. McNemar's test showed that PTS were identified correctly significantly less often when presented with bitter strips compared to when presented with blank (p = 0.002) or sweet strips (p = 0.017). Our results showed that bitter taste disrupts the spatial discrimination of piperine-evoked burning sensations. PTS might serve as a basis for further studies on disease-specific patterns in chemosensory disorders.

Smell loss as initial symptom of olfactory groove meningioma.

Approximately 20% of the general population suffer from olfactory dysfunction (OD). Until today, olfactory function (OF) receives less attention than other human senses despite its significance for quality of life. The main causes of OD are upper respiratory tract infections, traumatic brain injuries and sinonasal diseases. Here, we report the case of a 28-year-old woman, who started to suffer from OD during pregnancy. Smell loss was attributed to pregnancy-induced rhinitis and initiated no further examinations. Nevertheless, OD persisted post partum and undulating headache occurred 1 year later. Only after visual impairment and one more year passing by, diagnosis of olfactory groove meningioma was made using MRI. With this case report, we want to highlight the importance of the symptom of smell loss. Patients reporting OD should undergo thorough anamnesis, endoscopy of the nasal cavity, psychophysical smell testing and radiographic imaging in unclear cases to determine diagnosis.

Self-perceived Taste and Flavor Perception: Associations With Quality of Life in Patients With Olfactory Loss.

OBJECTIVE: To evaluate associations between self-perceived chemosensory functions of smell, taste, and flavor perception with olfactory-specific quality of life (QoL) in patients with olfactory dysfunction (OD) and whether these associations would be influenced by other factors, such as duration or etiology of smell loss. STUDY DESIGN: Retrospective cohort study. SETTING: Tertiary care, academic center. METHODS: Olfactory-specific QoL was measured with the Questionnaire of Olfactory Disorders (QOD). The QOD measures the impact of OD on QoL (QOD-negative statements) and the ability of patients to cope with smell loss (QOD-positive statements). Orthonasal olfactory function, patients' demographics, self-perceived chemosensory perception, and duration and etiology of OD were retrospectively collected in a cohort of patients with quantitative OD. Correlations and multivariable linear regression models were computed to determine possible associations with the outcome measure of QOD-negative and QOD-positive statement scores. RESULTS: A total of 133 patients with OD were included. Analysis revealed a positive correlation between self-perceived taste and flavor perception with QOD-negative statement scores, while self-perceived smell showed no significant correlation. Similarly, longer duration of smell loss and higher age were also correlated with higher QOD-positive statement scores. Multivariable regression models confirmed that self-perceived taste was independently associated with the QOD-negative statement score, while age and duration of OD were independently associated with the QOD-positive statement score. CONCLUSIONS: These findings suggest that the impact of diminished flavor perception during eating and drinking has a stronger impact on the QoL of patients with OD as compared with decreased orthonasal olfaction.

Decrease and Recovery of Olfactory and Gustatory Function in a Case of SARS-CoV-2 Infection.

Self-reported chemosensory dysfunction in severe acute respiratory syndrome coronavirus 2 patients is common. We present a case of reversible smell loss in a young patient with mild coronavirus disease 2019 infection assessed with established testing methods over a period of 8 weeks.

Association Between Orthonasal Olfaction and Chemosensory Perception in Patients With Smell Loss.

OBJECTIVES: Self-ratings seem to be the most effortless strategy for assessment of patients' chemical senses. Notably, although flavor perception strongly relies on olfaction, the relationship between self-reported flavor perception and orthonasal olfactory tests have hitherto not been considered. The aim of this study was to investigate the relationship between self-perceived olfactory function (SO), taste (ST), and flavor perception (SF) and smell test results in patients with olfactory dysfunction (OD). METHODS: We included 203 patients with quantitative OD. Group comparison, bivariate correlation, and ordinal logistic regression were employed to quantify the relationships between predictor variables (age, gender, reason for OD, and orthonasal olfaction-summed scores of threshold, discrimination, and identification [TDI]) and outcomes of SO and SF ("impaired," "average," or "good"). RESULTS: Group comparison revealed significant differences between SO and SF (P < .001). Stronger correlations were found between SO and TDI (r = 0.64), compared to SF and TDI (r = 0.27). No relevant correlation was found between ST and TDI (r = 0.10). Higher TDI was associated with odds of higher SO in univariate (odds ratio = 1.25) and multivariable analyses (adjusted odds ratio = 1.23), and both models showed good fit of data. Conversely, regression models on the associations between TDI and changes in SF did not meet the assumption of goodness of fit. CONCLUSION: We found that higher orthonasal olfactory performance was associated with odds of higher SO in patients with OD, even after controlling for olfactory-relevant factors. To the contrary, similar models based on flavor perception failed to describe these relationships. This indicates for SF and ST to be less represented by the TDI compared to SO. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:2213-2219, 2020.