Presentation Details
| A double-blind study of olfactory/sniff training with a randomized blank control group Richard Doty1, Crystal Wylie1, 3, Ronald Devere2, Vince Groso3, Shima Moein3, Marco Fornazieri4. 1University of Pennsylvania, Philadelphia, PA, NJ, USA.2Taste and Smell Disorders Clinic, Austin, TX, USA.3Sensonics International, Haddon Heights, NJ, USA.4Universidade Estadual de Londrina, Londrina, Brazil |
Abstract
Objectives: Persons with smell loss reportedly benefit “olfactory training” (OT). However, most OT studies ignore drop-out rates, lack double-blinding, and do not employ randomly assigned contemporaneous control groups to account for expectation, practice effects, regression to the mean, and spontaneous improvement. We addressed these shortcomings in a double-blind multi-center study, labelling the research “sniff training” to facilitate compliance. Methods: Of 134 smell-deficient patients we contacted, 96 agreed to participate. 27% did not complete the 4-month-long training period, resulting in a final study group of 70. The patients were andomly assigned to three 10-stimulus exposure groups: unlabeled odorants; labeled odorants; and odorless blanks. The UPSIT® was administered before and after the training period; 35 also received a smell threshold test. General linear models, ꭕ2, and other statistical analyses were employed. Results: Although 64% improved on the UPSIT®, with 26% experiencing clinically meaningful improvement (i.e., ≥4 points), the three odor exposure groups did not differ in terms of such improvement. A 6.2% improvement in UPSIT® scores occurred independent of exposure group (p=0.003). A trend in improved threshold scores independent of exposure group was also evident (p=0.078). Conclusion: We found in a double-blind placebo-controlled study that OT with a blank produced the same degree of improvement over a 4-month training period as OT with olfactory stimuli. Confirmation from other similarly designed studies is clearly needed.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.