Effects of Frequency-Controlled Ear Acupuncture on COVID-19- related Refractory Olfactory Dysfunction: a Randomized Clinical Trial.

Background: Olfactory dysfunction is a common COVID-19 symptom, posing treatment challenges.

Objectives: We aimed to investigate the efficacy of frequency-controlled ear acupuncture in treating COVID-19-related olfactory dysfunction.

Methods: A randomized, participant-blind clinical trial occurred at the Rasoul Akram Hospital (IRCT20210311050671N1). Forty patients were recruited, and 20 patients were randomly assigned to either the experimental or control group. The primary outcome was the improvement in patients' quality of smell. The olfactory dysfunction was confirmed using the Smell Identification Test. The intervention group received two sessions of acupuncture treatment according to auricular frequency treatment, with a one-week interval, while the control group received an equal number of switched-off laser sessions. Both groups were instructed to use nasal betamethasone drops. The patients were asked to rank their ability to smell before and after each intervention on a 10-point visual analog scale. Secondary outcomes were related side effects.

Results: Covariance analysis revealed a significant difference in adjusted scores between the groups (F [37, 1] = 37.463; p = 0.000, Eta² = 0.503). The smell quality improved from 2.80 ± 1.76 to 5.22 ± 3.40 after treatment in the intervention group (p = 0.007), while the control group showed no significant change (p = 0.184). Three patients reported short and transient side effects, such as nausea, headache, and dizziness, in the first hours after the intervention.

Conclusion: Frequency-controlled ear acupuncture is an effective option for treating COVID-19-related olfactory dysfunction. The study highlights the potential of alternative therapies in the treatment of this condition, and further research is warranted to investigate its long-term effects.