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Free keywords:
Ascending procedure; Olfaction; Single staircase procedure; Smell; Threshold
Abstract:
Introduction: Assessment of olfactory performance is of high clinical interest in the contexts of smell loss as well as neurological diseases, and recently gained attention in obesity research. Available olfactory tests, especially for assessing olfactory sensitivity, are time-consuming and require high cognitive capacity. Therefore, we aimed to establish a short procedure for reliably testing olfactory sensitivity using a subtest of the “Sniffin’ Sticks” battery. Evaluation criteria are test duration, validity, and test-retest reliability. Methods: In a preliminary study using a within-subject repeated-measures design, we measured olfactory sensitivity for n-butanol in 20 young and healthy participants. We compared sensitivity obtained with three different measures during two sessions in a pseudo-randomized order: a standard single-staircase three-alternative forced-choice procedure with seven reversals (SSP_7); an abbreviated version with five reversals (SSP_5); and an ascending presentation of 16 dilution steps from lowest to highest odor concentration (brief ascending procedure, BAP). Results: Compared to the SSP_7, the BAP was 51%, and the SSP_5 26% shorter in duration. Both the BAP and SSP_5 scores were highly correlated with the SSP_7. The test-retest reliability in all three tests was similar to that typically reported in olfactory research. Conclusion: The abbreviated tests are valid measures of olfactory sensitivity. Especially, the BAP is as reliable as the standard method, but remarkably faster and easier to perform. Implications: Thus, the short procedures bear potential for both research and clinical practice, especially for complex study designs with time constraints on olfactory testing and for patient populations with attention deficits.
