The COVOSMIA-19 trial: Preliminary application of the Singapore smell and taste test to objectively measure smell and taste function with COVID-19

Abstract

Sudden loss of smell and/or taste has been identified as an early symptom of SARS-CoV-2 2019 (COVID-19) infection, and presents an effective target for prompt self-isolation and reducing community spread. The current study sought to develop and test a novel, rapid, self-administered test to objectively measure smell and taste losses associated with COVID-19, and administered self-report questionnaires to characterise symptoms associated with COVID-19 in Singapore. Participants (N = 99) completed questionnaires to record recent changes in smell and taste ability. This was followed by the 'Singapore Smell and Taste Test' (SSTT), a personal, objective testing kit for daily self-assessment of smell and taste function at their place of residence. Seventy-two recruited participants were confirmed as COVID-19 positive at baseline, of which 58 completed the SSTT at home. Of these, 36.2% had objectively measured smell and/or taste loss. The SSTT measures of smell and taste function were positively associated with participants' self-reported smell and taste acuity, and rated smell intensity of 6 common household items. This study presents the first application of the SSTT as a rapid, cost-effective, objective tool to self-monitor smell and taste function in a residential setting, and ensures comparability across individuals through the use of standardised stimuli. The SSTT has potential for future application in populations with limited access to formal COVID-19 testing as a self-administered objective method to monitor sudden changes in smell and taste, and to prompt early self-isolation, in order to reduce community transmission of COVID-19.

Keywords: Ageusia; Anosmia; COVID-19; COVID-19, Coronavirus disease 2019; Gustatory dysfunction; Olfactory dysfunction; PCR, Polymerase Chain Reaction; SARS-CoV-2; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2; SNOT-22, 22-item Sino-Nasal Outcome test; SSTQ, The Singapore Smell and Taste Questionnaire; SSTT, The Singapore Smell and Taste Test; VAS, Visual Analogue Scale.

Fig. 1

Flow chart of test completion by participants. displays the tests complete by each participant. Each day of testing included the SSTT and the Common Household Items Test. CHI = Common Household Item.

Fig. 2

Mean composite scores on the SSTT at ‘day 1′ by COVID-19 test outcome and objective smell/taste function at ‘day 1′ (‘normosmic/geusic’ or ‘hyposmic/geusic’) (N = 65). displays the mean composite smell and taste scores on the SSTT at ‘day 1′ split by COVID-19 test outcome (positive/negative) and objective smell/taste loss at ‘day 1′ (‘normosmic/norm-geusic’ or ‘hyposmia/hypogeusia’). One COVID-19 negative participant was identified as exhibiting moderate hypogeusia. Error bars are 95% confidence intervals.

Fig. 3

Objective smell/taste function by category at ‘day 1′ for COVID-19 positive patients (N = 58) shows the number of COVID-19 positive participants in each category of smell and taste function as defined by our tiered scoring system.