Olfactory dysfunction in patients after recovering from COVID-19

Abstract

Background

Smell and taste disorders occur in COVID-19 with a high prevalence, but little is known about the duration of the symptoms. In particular, studies using validated olfactory tests are very rare to date.

Aims/Objectives

The aim of this study was to determine the olfactory function of COVID-19 recoveries by a detailed olfactory test.

Methods

91 patients with PCR-confirmed, past COVID-19 disease were included. Olfactory history was taken using a questionnaire. Olfactory function was evaluated with the sniffin' sticks test, tasting function with taste sprays.

Results

80 patients had experienced sudden olfactory loss during the course of disease and at the time of testing, 33 patients subjectively still had an impaired olfactory sense. Around 8 weeks had passed since the onset of symptoms. 45.1% of the tested individuals were still hyposmic according to the olfactory test while 53.8% showed an olfactory performance within the normal range. Patients’ self-assessment correlated poorly with the measured olfactory performance.

Conclusions and significance

Half of the patients with an olfactory loss as a symptom of COVID-19 still have olfactory impairments after two months, although not all of these patients subjectively notice a restriction. Long-term measurements must confirm whether all affected patients will make full recovery.

Chinese abstract

背景：气味和味觉障碍在COVID-19患者中发生率很高, 但关于症状的持续时间鲜为人知。特别是, 使用经过验证的嗅觉测试的研究至今还非常少见。

目的：本研究的目的是通过详细的嗅觉测试来确定COVID-19康复的嗅觉功能。

方法：纳入91例经PCR确诊的既往COVID-19患者。使用问卷调查获得嗅觉史。嗅觉功能通过嗅棒测试进行评估, 味觉功能通过味觉喷雾进行评估。

结果：80例患者在疾病过程中和测试时经历了突然嗅觉丧失。测试时, 有33例患者主观嗅觉仍然受损。自症状发作以来已经大约8周了。根据嗅觉测试, 有45.1％的被测者仍处于低氧状态, 而 53.8％被测者的嗅觉表现在正常范围内。患者自我评估与所测的嗅觉表现之间的相关性很差。

结论和意义：有一半具有嗅觉丧失这种COVID19症状的患者在两个月后仍有嗅觉障碍, 尽管并非所有这些患者在主观上都注意到了任何限制。必须进行长期测试以确认是否所有受影响的患者都会完全康复。

Keywords:

• Covid-19
• Sars-CoV-2
• smell disorders
• smell test
• Sniffin’ sticks

Disclosure statement

No potential conflict of interest was reported by the author(s).

Table 1. Duration and severity of the olfactory and taste disorder.

Table 2. Relationship between olfactory and taste function.