Sensitivity and specificity of prediction models based on gustatory disorders in diagnosing COVID-19 patients: a case-control study

Abstract

Objective: to quantitatively assess disturbances of sweet, sour and salty and bitter tastes in a group of young, asymptomatic or oligosymptomatic COVID-19 patients; establish a reliable, sensitive and specific test that can diagnose COVID-19 on the basis of taste disorders and publish the results according to STARD 2015 statement (Standards for Reporting Diagnostic Accuracy). Design: case-control study Setting: isolated rooms in the Central Clinical Hospital of the Ministry of the Interior and Administration in Warsaw (which had been transformed into an infectious hospital) and a dormitory in one of Warsaw universities. Participants: 52 SARS-CoV-2 positive (51 men, mean age 21.7 years) and 36 negative students (34 men, mean age 20.8 years). Main outcome measures: a gustatory function assessment (sweet, salty, sour and bitter taste), with flavour concentrations established previously in healthy subjects was conducted for all subjects. Each participant received one tasteless reference and nine flavour tablets with sucrose concentrations of 40, 80 and 106.4 mg/ml; NaCl at 13.5, 17 and 27 mg/ml; ascorbic acid at 6.25 and 12.5 mg/ml and grapefruit extract at 40 mg/ml. Results: the only taste that was impaired significantly more frequently in COVID-19 patients was the sweet taste at the lowest flavour concentration (40 mg/ml, p = 0.002). Different screening and diagnostic models were constructed using the examined variables. The highest accuracy screening test consisted of the positive result of a three-question questionnaire (self-reported loss of taste, self-reported loss of smell, or fever within the last month (positive if at least one present) and/or ageusia of sweet taste at a sucrose concentration of 40 mg/ml. The sensitivity of the model was 94% with a specificity of 55%. The highest accuracy diagnostic test consisted of ageusia of sweet taste at a sucrose concentration of 106.4 mg/ml or/and ageusia of salty taste at an NaCl concentration of 13.5 or 17 mg/ml. The specificity of the test was found to be 100%, and the sensitivity was 34%. Conclusion: as the most effective way of controlling the present pandemic involves testing the wider population for symptomatic, oligosymptomatic and asymptomatic carriers of SARS-CoV-2 and isolating or hospitalising infected subjects, in the present study, an inexpensive, simple, fast and sensitive (94%) screening test that can be used for such a purpose is proposed. In addition, a specific (100%) diagnostic test that could be used to refer patients to quarantine in the case of limited availability of genetic or serological tests is proposed.

Objective screening for olfactory and gustatory dysfunction during the COVID‐19 pandemic: A prospective study in healthcare workers using self‐administered testing

“… 32 , 33 , 34 While some studies have characterized the length and severity of smell and taste symptoms in COVID-19 patients, there is a growing recognition in the literature of the need for psychophysical gustatory testing in this population. 3 , 5 , 7 , 10 , 22 , 35 , 36 , 37 , 38 One goal of our study was to identify subjects with subclinical chemosensory dysfunction who do not have obvious symptoms of COVID-19. However, the low incidence of infection in our sample precluded us from such identification.…”

Oral Symptoms Associated with COVID-19 and Their Pathogenic Mechanisms: A Literature Review

“…Gustatory function is exclusively assessed by subjective or self-reported impressions of COVID-19 patients on taste alteration, whereas a small number of objective studies were performed by applying primary tastants to the tongue [ 22 , 49 , 74 , 82 , 90 ]. Although taste sensitivity is reduced with increasing age and is higher in females than males, the objective test has been considered reliable to assess the tasting ability [ 141 ].…”

“…Abalo-Lojo et al [ 70 ] demonstrated that complete taste, bitter taste, salty taste, and sweet taste loss are present in 75.7%, 8.1%, 4.1%, and 1.4% of COVID-19 patients, respectively. Adamczyk et al [ 74 ] qualitatively assessed gustatory disorder by using solutions of sucrose (40–106.4 mg/mL), NaCl (13.5–27 mg/mL), ascorbic acid (6.25–12.5 mg/mL), and grapefruit extract (40 mg/mL). Sweet taste was especially impaired in COVID-19 patients, who could not recognize the lowest sucrose concentration.…”

“…Gustatory and olfactory symptoms predict COVID-19 with the sensitivity of 70% and the specificity of 73–90.3% [ 48 , 93 ]. When assessing COVID-19 patients by using solutions of sucrose (106.4 mg/mL) and NaCl (13.5 or 17 mg/mL), ageusia of sweet and/or salty taste corresponds to the highest accuracy diagnostic test with the specificity of 100% and the sensitivity of 34% [ 74 ]. Given the onset time and the relation to disease severity, gustatory dysfunction is usable as a symptom for COVID-19 diagnosis at an early stage and in asymptomatic patients.…”

Human Taste Cells Express ACE2: a Portal for SARS-CoV-2 Infection

“…1,2 Interestingly, RNA for SARS-CoV-2 was detected in the submandibular glands and tumor of a patient undergoing tongue surgery for squamous carcinoma two days before the patient developed symptoms and had a positive nasal swab for the virus: 3 however, taste tissue was not examined. The sensory symptoms need not be unitary as the virus can independently target all or any combination of the senses 4,5 and may even cause deficits or changes in a specific taste quality. Branches of five cranial nerves (CN I [smell], V [chemesthesis: heat, pungency], and VII, IX and X [taste, Figure 1A] are involved in relaying those specific senses to the central nervous system.…”