Retronasal olfactory testing using candies sent by post and for screening purposes: a feasibility study

Abstract

Background: The olfactory system is able to detect external odours through the orthonasal-and internal odours through the retronasal route. Flavour perception strongly relies on the sense of smell and this back route. In contrast to orthonasal, retronasal olfactory tests (ROT) are less frequently applied, although testing should be recommended for several reasons. The aim of the present investigation was to propose a suitable form of ROT for home-testing (and postal distribution) and evaluate a retronasal screening test.Methodology: Initially, 111 participants were tested using a 27-item version of the Candy Smell Test (CST). Fifty-four participants performed retesting, of which 25 subjects did so in a home-setting being supplied with professionally packed "candy-chains". Seven candies were chosen by means of hit rate differences in normosmics and severely hyposmics/anosmics. The 7-CST is designed in a non-forced-choice fashion with same seven flavours to choose from.Results: For the 27-item CST both groups (subjects performing home-testing and those performing retesting at the clinic) showed highly significant test-rest-reliabilities. The 7-CST was capable of discriminating healthy from diseased subjects when being tested in 116 healthy subjects and 47 patients suffering from olfactory dysfunction. Conclusion:The CST is suitable for home-testing and postal distribution. The new 7-item CST can be valuable for rapidly revealing anosmics. These findings help in further standardizing ROT, may encourage rhinologists to more routinely evaluate retronasal olfactory abilities and pave the way for larger epidemiologic studies also in regard to food preferences and nutritional behaviour.

Ortho- and retronasal olfactory performance in rhinosurgical procedures: a longitudinal comparative study

“…15.9 ± 7.5 11.4 ± 3.6 p = 0.0574 Olfactory assessment in a pre-surgical setting is often reduced to sheer asking for complaints and/or fast screening tests, though both strategies can be misleading. Subjective ratings of olfactory capacity are inconsistent and may show significant correlations in patients with OD [19,31]. On an individual basis, patients with OD of different etiologies do not rate their abilities consistently accurate.…”

“…Retronasal olfactory function was tested using the Candy-Smell-Test (CST) [17][18][19]. Validated in a 23-item version [17], in this study, we applied a 27-item version (for aromas and distractors, please see [20]).…”

Body-Mass-Index Associated Differences in Ortho- and Retronasal Olfactory Function and the Individual Significance of Olfaction in Health and Disease

“…Our group routinely recorded the BMI and provided patients with the questionnaire on the individual significance of the sense of smell (see below). Olfactory test results were part of a recent publication [15]. For retrieval of this data, permission was granted by the local ethics committee (amendment 08/2019).…”

“…Retronasal olfactory function was tested using the Candy Smell Test (CST) [21,22]. Originally validated in a 23-item version [21], we applied a 27-item version in all subjects [15,23]. For this version, less-identifiable aromas of the original items [21] were removed (three aromas: passion fruit, strawberry and kiwi) and others introduced (seven aromas, see Table 1.)…”

Individual importance of olfaction decreases with duration of smell loss

“…Thus, in this study, we sought to determine whether the individual significance of olfaction decreases with duration of OD and whether factors such as degree of olfactory function or etiology of the OD may modulate this relationship. of quantitative OD or were recruited as healthy volunteers for a recent research project (22) . We evaluated all subjects that underwent thorough olfactory testing between 1/2017 and 11/2019 and included those that filled out the importance of smell questionnaire (IOQ) prior to testing as part of a routine pre-testing procedure.…”