Discussion:
Olfactory dysfunction is known to affect the quality of life as patients with olfactory dysfunction report difficulties with cooking, decreased appetite and challenges with maintaining personal hygiene and social relationships, fear of hazardous events (5) .
Post viral anosmia is one of the main reasons for smell dysfunction in adults (40% of cases of anosmia). Common cold viruses or upper respiratory tract infections are well known to cause post-infectious smell loss. The previously described coronaviruses are assumed to account for 10-15% of cases. So that, the COVID-19 virus supposed also to be able to cause anosmia in infected patients and if it occurs, it is not a specific finding (16) .
Olfactory dysfunction in COVID-19 patients, which can be the only presenting symptom or with other symptoms, but its pathogenesis is still not fully understood. It may result from viral-induced olfactory nerve damage, local inflammation of the nasal passage, or both (17) .
In Kanjanaumporn et al. (3) study, short-term smell and taste recovery rate was approximately 44-74%, which is higher than previous reports of other post-viral olfactory dysfunction such as rhinovirus, influenza, respiratory syncytial virus, and other coronaviruses. Overall, 48.6–89% of COVID-19 patients with Olfactory dysfunction experience complete remission or improvement after 4 weeks of follow-up(18) .
Le Bon et al. (19) in their systematic review showed that there is no strong evidence to support using oral and topical corticosteroids in patients with post-infection olfactory dysfunction. However other studies like Kanjanaumporn et al.(3) stated that topical steroid treatment has improved the chance of recovery in post-infectious olfactory dysfunction.
Our results support the results of Le Bon et al. (19) as no statistically significant difference in improvement after topical steroid usage combined with olfactory training in group B (60%) of patients exhibited clinical improvement by the fouth week of treatement compared to 56.6% in the control group A (olfactory training alone), and this result matches with Abdealim et al. (20) and Hintschich et al. (21) studies who suggested that using topical mometasone furoate nasal spray in the treatment of post COVID- 19 anosmia offers no benefits over olfactory training.
In a retrospective cohort study by Hummel et al. (22) revealed a benefit from intranasal vitamin A 10000 IU per day in addition to olfactory training in the treatment of post-infectious olfactory loss for two months of treatment.
Our resuts shows minor improvement rates in group C after combining topical vitamin A with olfactory training 70 % of patients showed clinical improvement by the end of fourth week compared to 56.6 % in the control group A but this is not significantly differed from olfactory training alone or with combined topical steroid usage after 4 weeks.
Our resuts shows inconclosive improvement rates in group D combined topical theophylline with olfactory training (70%) of patients showed clinical improvement by the end of fourth week compared to 56.6 % in the control group A and this is also not superior than olfactory training alone,combined topical steroid nor combined topical vitamin A usage after 4 weeks, and this results matches the results of Gupta et al. (23) and Lee et al. (24) studies.
By following the improvements in the study, all groups showed significant improvements over the first three weeks of the study. Comparing the smell scores between the studied groups, there was superiority for the study group (group B) of topical mometasone nasal spray, and (group C) topical vitamin A and (group D) topical theophylline over the control group (group A) olfactory training alone as the comparison of smell scores between all groups after 1 week, 2 weeks and 3 weeks of treatment, showed statistically significant differences between groups, (P-values were <0.001*) but no final significant difference between smell scores between groups after the end of the fourth week (p-value= 0.6) .
Regarding the duration of anosmia/hyposmia and the recovery rates, there was a statistically significant difference as the average time for complete recovery in group B was 25.7 ± 9.20 days and group C was 24.8± 6.67 days and in group D was 23.5± 7.13 days compared to 28.97 ± 4.29 days in the control group A (P = 0.02*) . These results show that intranasal vitamin A application and topical usage of theophylline help to shorten the duration of post-COVID-19 anosmia/hyposmia.
Our study revealed no significant association between age, sex ,place of management, severity of COVID-19 illness, obesity and the duration of COVID-19 illness with smell scores and the duration of anosmia/hyposmia in the studied groups but showed a high significant association between other prognostic factors as; diabetes (P-Value=<0.001***) , hypertension (P-Value=<0.001***) , smoking (P-Value=<0.001***) , and asthma (P-Value=<0.001***) and full recovery within 4 weeks. We found a significant positive correlation between asthma and both smell scores after 4 weeks and duration of anosmia/hyposmia p-values were 0.01* and 0.03* respectively.
These results as regards the prognostic factors differ from Esquinas-Requena et al. (25) , who confirmed that the only prognostic factor of persistent olfactory/taste dysfunction in COVID-19 patients was the absence of fever as they studied the prognostic factors during the period of COVID-19 illness, not after patient recovery.
Conclusion :
This study suggests that combining the usage of topical mometasone furoate or topical vitamin A or intranasal theophylline with olfactory training shortens the duration of post-COVID- 19 anosmia/hyposmia but offers no superiority regarding smell scores over olfactory training alone after 4 weeks.
Age, sex, place of management, severity of COVID-19 illness, obesity and the duration of COVID-19 illness can be rolled out as discriminative prognostic factors affecting the duration of anosmia but diabetes, hypertension, smoking and asthma can affect the full recovery within four weeks.