Retronasal Screening of Olfactory Function with the 7-Item Candy Smell Test

Introduction:

The sense of smell helps us to fully enjoy food intake. Flavor perception is essentially influenced by retronasal perceived odor molecules. Ortho- and retronasal olfactory performance may differ – especially in patients with polyposis. For retronasal smell testing the validated Candy-Smell-Test (CST) was introduced in 2009. Aim of this study was to investigate for a short retronasal screening test with selected items from the CST.

Methods:

31 healthy subjects (18 f, 13 m; age mean/SD 28.6/9.4 years) and 21 patients complaining of olfactory dysfunction (OD) (14 f, 7 m; age 58.0/16.5 years) were tested using 27 different candies. Test-Retest-Reliability was studied, also in home settings. Orthonasal function was tested using sniffin' sticks (TDI) enabling comparison to normative data. Correct answers on the 27 CST and pretests helped determining 7 candies establishing the new 7-item CST. The test was performed in a non-forced-choice paradigm: subjects chose from a list of 7 possible flavors, or had the option to select “no flavor” and “undefinable”.

Results:

Ortho- and retronasal tests correlated significantly (r52 = 0.90; p < 0.001). Differences (healthy vs. OD patients) were most prominent in 9 odors, from which coffee, anise, vanilla, coconut, orange, pineapple and raspberry were chosen for a final 7-item CST. Analysis revealed a mean score of 2.4 ± 1.9 in OD patients and 6.0 ± 1.0 in healthy subjects. Our data show that OD patients are unlikely to score more than 4 points on the new 7-item CST.

Conclusion:

The results of the new 7-item CST show its usefulness in the screening for olfactory dysfunction. It is an easy to perform and valuable in epidemiologic studies, as well as in follow-up investigations. Further investigations need to obtain normative data.

Publication History

Publication Date:
23 April 2019 (online)