Losing olfaction in COVID-19: Screening, training and effects on quality of life

Background & aims

Olfactory disorders impact mental health, with adverse effects on quality of life, particularly in the area of eating. Despite their high prevalence in the population, olfactory disorders are poorly managed, with patients still lacking easy access to rapid diagnosis and treatment. In this context, the present study offers a new screening tool and compares the efficiency of different olfactory training protocols.

Methods

A screening test was set up and different olfactory training paradigms were compared for their effect on the recovery of the sense of smell on the one hand, and quality of life on the other. The study population was composed of post-COVID-19 dysosmic patients (with a loss of more than 6 weeks). Three training protocols were used, differing in terms of number of odors and in format (either lab-supplied odorant kits, or the use of odorants found at home). All three protocols were implemented over a 12-week period.

Results

The screening test distinguished dysosmics from normosmics with an accuracy of 73%. During training, 69% of patients completed the evaluation protocol and 77% of them performed more than half of the training sessions, resulting in a 53% completion rate. Olfactory performances improved significantly after training, irrespective of the training paradigm and 59% of patients displayed a clinically significant improvement of their sense of smell. These improvements were positively associated with assiduity along training. Finally, olfactory disorders negatively affected quality of life. After olfactory training, this overall negative impact on quality of life was reduced, especially with regard to the pleasure of eating.

Conclusion

This study introduces a new screening tool for olfactory deficits. It also provides important insights into the optimization of olfactory training protocols and their effects on quality of life, and on eating behavior in particular.