The overlooked Covid-19 symptom

Testing times: Healthcare workers taking swab samples for Covid-19 from residents at Dewan Masyarakat Taman Meru 3, Klang. Scientists say there was the possibility that healthcare workers might be more focused on looking out for critical symptoms such as lung infection rather than the loss of smell in patients. — KK SHAM/The Star

PETALING JAYA: The loss of smell among Covid-19 patients may be more common than thought, with higher incidences reported among female patients than in males, a study by Malaysian scientists showed.

A recent meta-analysis – the examination of data from multiple studies on the same subject – conducted by Malaysian academicians suggested that the loss of smell may be an under-reported symptom among Covid-19 patients.

They also found more cases of smell dysfunction were reported among females (61.4%) compared to males (38.6%).

“This could be explained by gender-related variation in the inflammatory process, or that more women are willing to take part in the studies.

“Another reason might be that women tend to be sensitive to any change in their chemosensory function, ” the authors said.

They also found that higher reported smell dysfunctions were observed in European (54%) and North American (51%) populations compared to Asians (31%).

“The underlying socio-cultural background of Asian patients such as their reserved nature or lack of awareness of smell dysfunction as a symptom might account for this, ” they said.

The scientists added that there was also the possibility that healthcare workers might be more focused on looking out for critical symptoms such as lung infection rather than the loss of smell.

“This study highlights the significance of smell loss as an early symptom of Covid-19 patients. The findings of under-reporting in Asians and in men imply that it must be specifically queried to avoid misdiagnosis, ” they said.

In the study, a larger percentage of Covid-19 patients were found to have lost their sense of smell when objective means were used to measure smell dysfunction, compared to subjective methods.

“Interestingly, the prevalence

of olfactory dysfunction was observed to be higher in Covid-19 patients on objective rather than subjective evaluations (72.1% versus 44.53%).

“This could be attributed to the fact that most Covid-19 patients are unaware of their olfactory dysfunction leading to the possibility of underestimation, ” they added.

They cited a study in which 98% of Covid-19 patients were found to have olfactory dysfunction after taking the University of Pennsylvania smell identification test, when only 35% of them were initially aware of their symptoms.

“Thus it is worth noting that the prevalence of olfactory dysfunction may be higher if tested objectively, ” they said.

Quantitative testing of smell loss, they proposed, may provide rapid and cheap modality to screen Covid-19 in a large population.

“Applying a specific questionnaire to detect olfactory dysfunction, especially in those with suspicious flu-like symptoms, travel history from affected countries and contact with Covid-19 patients, may enhance the pick-up rate of infected patients, ” the study said. The study, titled “Prevalence of olfactory dysfunction in coronavirus disease 2019 (Covid-19): A meta-analysis of 27,492 patients”, was published in the medical journal The Laryngoscope on Nov 20.

The meta-analysis looked at data from 83 high-quality studies from 27 countries and was authored by Dr Jeyasakthy Saniasiaya from Universiti Malaya, Dr Md Asiful Islam and Prof Dr Baharudin Abdullah, both from Universiti Sains Malaysia.

The authors had also found that the overall prevalence of smell dysfunction among Covid-19 patients was about 48%.

“Anosmia, hyposmia and dysosmia were observed in 35.39%, 36.15% and 2.53% of the patients respectively, ” they wrote.

Anosmia is the partial or complete loss of smell, hyposmia is the decreased sense of smell while dysosmia is disordered smell perception.

The loss of smell was also higher among patients with a mild case of Covid-19 patients (47.48%), compared to those with a severe case of the infection (only 9.02%).

They suggested more research to be conducted to determine the specific odours that may be affected by the Covid-19 infection.

“By identifying the specific associated odour linked to the infection, a simple smell test can be developed particularly to screen for Covid-19, ” they said.

They also found that nasal symptoms among Covid-19 positive patients were scarcely reported.

This suggests that while there is evidence of a strong link between Covid-19 and loss of smell, runny or blocked noses do not appear to be common symptoms among Covid-19 patients.