Interventions for the treatment of persistent post-COVID-19 olfactory dysfunction.

Area of Science:

• Otolaryngology
• Infectious Diseases
• Systematic Review

Background:

• Olfactory dysfunction (OD) is a sensitive early marker of COVID-19.
• Persistent hyposmia or anosmia significantly impacts quality of life.
• Limited guidance exists for treating post-COVID-19 OD.

Purpose of the Study:

• To assess the benefits and harms of interventions for persistent post-COVID-19 OD.
• To maintain an up-to-date evidence base using a living systematic review approach.

Main Methods:

• Systematic review of randomized controlled trials (RCTs) in participants with post-COVID-19 OD (symptoms ≥ 4 weeks).
• Searched multiple databases up to December 16, 2020.
• Primary outcomes: smell recovery, quality of life, serious adverse effects. Assessed evidence certainty using GRADE.

Main Results:

• One small RCT (18 participants) compared oral steroids plus nasal irrigation to no intervention.
• Very low-certainty evidence suggests a potential benefit in smell recovery (CCCRC score ≥ 90) at 40 days (RR 11.00).
• The intervention group showed a greater median improvement in smell function (CCCRC score) compared to the control group.

Conclusions:

• Very limited evidence exists on treatments for persistent post-COVID-19 OD.
• The single included study showed very uncertain benefits and harms for systemic steroids and nasal irrigation.
• Ongoing trials are being monitored for future updates to this living systematic review.