Interventions for the prevention of olfactory dysfunction after persistent COVID-19
Webster KE, O'Byrne L, MacKeith S, Philpott C, Hopkins C, Burton MJ Interventions for the prevention of olfactory dysfunction after persistent COVID-19. Cochrane Database of Systematic Reviews 2021, No. 7. Art. No.: CD013877. doi: 10.1002 /14651858.CD013877.pub2. Accessed July 28, 2021.
Commentary
This study was conducted to evaluate the effects (benefits and harms) of interventions used or proposed to prevent persistent olfactory dysfunction caused by COVID-19 infection. It also aimed to keep the evidence up-to-date by using a live systematic review approach.
The main findings included one study of 100 participants that compared nasal steroid sprays with no intervention, and participants in both groups were advised to undertake olfactory training for the duration of the study.
Data were identified for only two of the pre-specified outcomes in this review, and there were no data on the primary outcome of serious adverse effects.
In the one comparing intranasal corticosteroids compared to no intervention, the presence of normal olfactory function after three weeks of treatment was self-assessed using a visual analog scale. Evidence for an effect of intranasal corticosteroids on the recovery of olfactory self-assessment is very uncertain.
No changes in olfaction were reported, but olfactory self-assessment scores were reported at the study endpoints on the same visual analog scale (after 3 weeks of treatment). The median score at the endpoint was 10 for the group that received nasal corticosteroids and 10 for the group that did not receive the intervention.
The authors concluded that
Evidence on the effectiveness of interventions in preventing persistent olfactory dysfunction after COVID-19 infection is very limited, but several additional ongoing studies in this area have been identified.
Because this is a living systematic review, the evidence will be updated periodically to incorporate new data from these and other relevant studies as they become available.
In this (first) version of the Living Review, we identified a single study of nasal corticosteroids for inclusion in this review and provided data from only two of the pre-specified outcomes.
The certainty of the evidence was so low that we were unable to determine whether nasal corticosteroids have beneficial or harmful effects.
