They conducted this study by comparing the use of scent cards and PCR diagnostic testing for COVID-19 for swabs collected from the nose.
‘A new COVID-19 screening tool that detects the sense of smell has been discovered.’
The novel scent card (SAFER Diagnostics) contains a single scent in a scratch-and-sniff label from where the participant needs to identify from 8 answer options: lemon, grape, floral, blueberry, banana, mint, unsure, or no scent. The answers are processed electronically via a QR code. An incorrect choice is classified as OD.
The demographics, medical history, COVID-19 symptoms, and subjective smell function on a binary and 10-point visual analog scale (VAS, with 0 indicating no sense of smell and 10 indicating normal sense of smell) of participants are also collected.
The results of the study show that among the participants who tested PCR-positive for COVID-19, 75% (12 out of 16) failed the olfactory screening compared to 4.8% (7 out of 147) among those testing PCR-negative for COVID-19. Only 37.5% (6 out of 16) of COVID-19 test-positive participants reported subjective loss of smell.
This demonstrates that a rapid smell detection test is feasible as a screening tool for COVID -19 but individuals may fail to recognize OD that is detectable on objective testing.
A screening test ideally gives importance to high sensitivity with potential lower specificity. Whereas, this novel olfactory test alone has a sensitivity of 75% and specificity of95.2% in detecting COVID-19 using PCR testing as the gold standard.
The optimal number of screening odorants required to achieve high sensitivity while maintaining practicality can be studied in the future studies.Combining screening of loss of smell with other common COVID-19 symptoms can help to increase the sensitivity.
Future studies with larger sample size and a heterogeneous population may better account for other OD risk factors and optimize sensitivity using a combination of OD testing with other symptoms for screening COVID-19.
Source: Medindia
