Olfactory function trends in COVID-19 patients: a prospective cohort study

Abstract

Background

One of the most common symptoms in COVID-19 patients is olfactory and taste dysfunction.

Aims/objectives

This study aimed to evaluate the olfactory threshold, and identification using objective tests in the Iranian population.

Material and methods

The present study was a prospective cohort study conducted in 2020–2021 on clinically recovering COVID-19 patients. Olfactory function was evaluated at the baseline, 4–6 weeks, and 12 weeks later. Olfactory threshold assessment was performed using the Saba Sabalan kit. The Iranian version of the Pennsylvania Smell Identification Test (IR-SIT) was used for olfactory identification. The olfactory threshold was categorized as poor (<8) and good olfaction (≥8).

Results

In the present study, 111 patients were examined, including 55 men and 56 women (mean age 41.4 and 53.4 years, respectively). The mean olfactory threshold was better for men (7.2) than for women (6.6). Analysis showed age to have a negative relationship with good olfaction at baseline (OR = 0.93, p = .05). Using IR-SIT, only 29.7% had normal olfactory function. Using linear regression, smoking was found to be significantly related to baseline IR-SIT score (adjusted Beta <0.001, p = .03).

Conclusions and significance

Objective tests are appropriate methods for assessing olfactory dysfunction in COVID-19 patients. Further studies are recommended.

Chinese Abstract

背景：COVID-19 患者最常见的症状之一是嗅觉和味觉功能障碍。

目的：本研究旨在评估嗅觉阈值, 并使用对伊朗人群的客观测试进行识别。

材料和方法：本研究是一项于 2020-2021 年对临床康复的 COVID-19 患者进行的前瞻性队列研究。在基线、4-6 周和 12 周后评估嗅觉功能。使用 Saba Sabalan 试剂盒进行嗅觉阈值评估。伊朗版本的宾夕法尼亚气味识别测试 (IR-SIT) 用于嗅觉识别。嗅觉阈值分为较差嗅觉（< 8）和良好嗅觉（≥ 8）。

结果：在本研究中, 111 名患者接受了检查, 其中男性 55 名, 女性 56 名（平均年龄分别为 41.4 岁和 53.4 岁）。男性的平均嗅觉阈值（7.2）优于女性（6.6）。分析显示年龄与基线时良好的嗅觉呈负相关（OR = 0.93, p = .05）。使用 IR-SIT, 只有 29.7% 的人嗅觉功能正常。使用线性回归, 发现吸烟与基线 IR-SIT 评分显著相关（调整后的 Beta < 0.001, p = .03）。

结论和意义：客观测试是评估 COVID-19 患者嗅觉功能障碍的合适方法。建议进行进一步研究。

Keywords:

• COVID-19
• smell
• olfactory dysfunction
• SARS-CoV-2
• recovery

Compliance with ethical standards

This study was compliant with ethical standards.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by grant 2240 from the Guilan University of Medical Sciences, Rasht, Iran.