Olfactory training using nasal inserts is more effective due to increased adherence

The recommended treatment for hyposmia (a clinically reduced sense of smell) is olfactory training using odor containers that the patients smell twice a day for several weeks. Adherence to the olfactory training regimen is, however, generally low. We aimed to investigate if a new form of odor delivery, using scented nasal inserts, could enhance adherence to olfactory training by allowing participants to be mobile during the training and thereby lower the perceived intrusion on everyday life.

Using a randomized controlled parallel-group design, individuals (N = 116) with hyposmia underwent 8 weeks of olfactory training. One group was assigned olfactory training using scented nasal inserts (nasal devices that retain nasal patency) while the other group was assigned the standard care regimen currently recommended by the Swedish healthcare system. We assessed objective and subjective olfactory ability before and after olfactory training as well as adherence to training.

Both groups significantly improved both their objective and subjective olfactory abilities, and training with nasal inserts produced similar improvement as standard care in overall treatment outcome. However, there was a significantly greater increase in discrimination performance and lower dropout rate (6.7%) in the nasal insert compared to the standard care group (23.2%). Critically, after exclusion of the drop-out participants, the nasal insert group still showed significantly higher adherence to the training regimen.

Olfactory training with nasal inserts could serve as a more effective form of treatment for hyposmia due to patients' improved adherence to protocol and increased tendency to finish their treatment regimen.