Changes in smell, taste occur frequently with COVID-19, sometimes prior to other symptoms
Click Here to Manage Email Alerts
Hyposmia and dysgeusia — or changes in smell and taste, respectively — represented common symptoms of COVID-19 in a single-center retrospective analysis from Italy of hospital admissions during a 1-month period early in the pandemic.
“Many patients admitted for COVID-19 infection complained about change in taste/smell perception and, when asked directly and more thoroughly, we noted that some of them recalled those as the first symptoms experienced,” Francesco Bax, MD, a neurology resident in the clinical neurology unit at the University of Udine in Italy, told Healio Neurology. “Therefore, we were encouraged to evaluate how prevalent these disturbances were within our population of patients and how often they appeared before other symptoms, believing that their characterization could help us in understanding something more about the first phases of the infection.”
Bax and colleagues examined the rate of hyposmia and dysgeusia among patients with COVID-19, as well as the relationship between these symptoms and the onset of others, in a group of patients admitted to the non-intensive COVID-19 unit of Udine University Hospital based on a positive swab test and/or clinical and radiological signs of SARS-CoV-2 infection. Admissions occurred during March 2020.
The researchers interviewed 141 consecutive patients (mean age, 62.6 years [range, 19-91 years]; 66.7% male) admitted to the hospital. They excluded 48 patients (34%) and completed interviews with 93 patients (66%).
Of the 93 patients interviewed, 58 experienced hyposmia and dysgeusia (62.4%). Among those patients, 22.4% “clearly” experienced olfactory and gustatory impairment before systemic symptoms, according to the study results. Age and sex distribution did not differ between the hyposmic group and that of the entire population interviewed.
The researchers observed “very limited” active smoking in both groups (hyposmic group = 8.6%; normosmic group = 2.9%; OR= 3.2 [95% CI, 0.3-28.6]). Total leukocyte and neutrophil counts were lower in the hyposmic group (23% [effect estimate, 1.23; 95% CI, 1.06-1.42] and 29% [effect estimate, 1.29; 95% CI, 1.07-1.54], respectively). Bax and colleagues observed no differences for other inflammatory biomarkers.
Few hyposmic patients (n = 6; 10.3%) experienced rhinorrhea and/or nasal congestion and only two of these patients (3.4%) reported asthma in their medical history, according to the findings. Approximately 10% of patients (10.3%; n = 6) reported a history of allergic rhino-conjunctivitis. One patient who reported pre-existing hyposmia noted worsening of the symptom 2 days before the onset of systemic symptoms; the worsening continued at the time of this patient’s interview. Among non-hyposmic patients, one reported a history of nasal polyposis.
The rates of hyposmia and dysgeusia in the present study “are in line” with the figures reported in the current literature, according to Bax. He noted that prevalence estimates for hyposmia and dysgeusia in COVID-19 vary from study to study, primarily because of the diversity of the patient populations analyzed and the different tools used to measure these sensory disruptions.
“A recent meta-analysis [by Agyeman and colleagues] that considered more than 8,000 patients from 24 studies reported a pooled prevalence of approximately 40% for both hyposmia and dysgeusia, but the range varied between the different studies considered,” Bax said.
The finding that hyposmia and dysgeusia may appear in some patients before other symptoms of COVID-19, such as fever or cough, could serve as “a warning sign” of a coming infection and prompt self-isolation to limit the spread of the disease.
Currently, however, there are no approved treatments for hyposmia and dysgeusia in COVID-19, Bax noted. In most cases, these symptoms are transient and often resolve on their own.
“Nevertheless, some patients may experience longer duration of taste and olfaction impairment, but more evidence is needed to understand what the exact mechanisms underlying these symptoms and their possible longer duration are,” Bax said.
References:
Agyeman AA, et al. Mayo Clin Proc. 2020;doi:10.1016/j.mayocp.2020.05.030.
McGovern Medical School. Hyposmia and anosmia. Available at: https://med.uth.edu/orl/2020/01/09/hyposmia-and-anosmia/. Accessed Dec. 17, 2020.
National Institute on Deafness and Other Communication Disorders. Taste disorders. Available at: https://www.nidcd.nih.gov/health/taste-disorders. Accessed Dec. 17, 2020.