Patterns of smell recovery in 751 patients affected by the COVID-19 outbreak

Abstract

Background and purpose: Post-viral olfactory dysfunction is well established and has been shown to be a key symptom of COVID-19 with more than 66% of European and US patients reporting some degree of loss of smell. Persistent olfactory dysfunction appears to be commonplace and will drive the demand for general practitioner, otolaryngology or neurology consultation in the next few months - evidence regarding recovery will be essential in counselling our patients.

Methods: This was a prospective survey-based data collection and telemedicine follow-up.

Results: In total, 751 patients completed the study, of whom 477 were females and 274 males. The mean age of the patients was 41 ± 13 years (range 18-60). There were 621 patients (83%) who subjectively reported a total loss of smell and 130 (17%) a partial loss. After a mean follow-up of 47 ± 7 days (range 30-71) from the first consultation, 277 (37%) patients still reported a persistent subjective loss of smell, 107 (14%) reported partial recovery and 367 (49%) reported complete recovery. The mean duration of the olfactory dysfunction was 10 ± 6 days (range 3-31) in those patients who completely recovered and 12 ± 8 days (range 7-35) in those patients who partially recovered.

Conclusions: According to our results, at this relatively early point in the pandemic, subjective patterns of recovery of olfactory dysfunction in COVID-19 patients are valuable for our patients, for hypothesis generation and for treatment development.

Keywords: COVID-19; anosmia; coronavirus; olfaction; recovery; smell.

Figure 1

Study flowchart. Eleven patients initially considered in the group of normal smell developed an olfactory dysfunction. Four hundred and eighty patients were not included due to incomplete follow‐up data (362, 75.4%), lost to follow‐up by impossibility to contact the patient (61, 12.7%), because they refused to participate for personal reasons (48, 10%) or due to the need for intensive care unit admission (9, 1.9%). *To consider COVID‐19 negative patients were tested almost three times. **Persistent loss was considered in those patients who did not report any improvement. ***Partial recovery was considered in those patients who subjectively started to smell some odours.