Trial Report Long-Term Taste and Smell Outcomes After COVID-19, Sharetts et al, 2024

[John Mac]

https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2817869

Key Points

Question What is the association of COVID-19 with long-term outcomes in taste and smell function as measured by state-of-the-art psychophysical tests?

Findings In this cross-sectional study of 340 individuals with and 434 individuals without prior COVID-19, taste function did not differ between individuals who had contracted COVID-19 one year earlier and those who had not, whereas some olfactory dysfunction was present in 30.3% of individuals with prior COVID-19 but only 21.0% of individuals with no history of infection. Deficits were greatest for individuals with the original untyped and Alpha variant infections.

Meaning These findings suggest that long-term taste loss perceived by many patients with COVID-19 likely reflects the loss of flavor sensations from odorant molecules reaching a damaged olfactory epithelium via the nasopharynx rather than the taste buds.

Abstract

Importance Self-report surveys suggest that long-lasting taste deficits may occur after SARS-CoV-2 infection, influencing nutrition, safety, and quality of life. However, self-reports of taste dysfunction are inaccurate, commonly reflecting deficits due to olfactory not taste system pathology; hence, quantitative testing is needed to verify the association of post–COVID-19 condition with taste function.

Objective To use well-validated self-administered psychophysical tests to investigate the association of COVID-19 with long-term outcomes in taste and smell function.

Design, Setting, and Participants This nationwide cross-sectional study included individuals with and without a prior history of COVID-19 recruited from February 2020 to August 2023 from a social media website (Reddit) and bulletin board advertisements. In the COVID-19 cohort, there was a mean of 395 days (95% CI, 363-425 days) between diagnosis and testing.

Exposure History of COVID-19.

Main Outcomes and Measures The 53-item Waterless Empirical Taste Test (WETT) and 40-item University of Pennsylvania Smell Identification Test (UPSIT) were used to assess taste and smell function. Total WETT and UPSIT scores and WETT subtest scores of sucrose, citric acid, sodium chloride, caffeine, and monosodium glutamate were assessed for groups with and without a COVID-19 history. The association of COVID-19 with taste and smell outcomes was assessed using analysis of covariance, χ2, and Fisher exact probability tests.

Results Tests were completed by 340 individuals with prior COVID-19 (128 males [37.6%] and 212 females [62.4%]; mean [SD] age, 39.04 [14.35] years) and 434 individuals with no such history (154 males [35.5%] and 280 females [64.5%]; mean (SD) age, 39.99 [15.61] years).

Taste scores did not differ between individuals with and without previous COVID-19 (total WETT age- and sex-adjusted mean score, 33.41 [95% CI, 32.37-34.45] vs 33.46 [95% CI, 32.54-34.38]; P = .94).

In contrast, UPSIT scores were lower in the group with previous COVID-19 than the group without previous COVID-19 (mean score, 34.39 [95% CI, 33.86-34.92] vs 35.86 [95% CI, 35.39-36.33]; P < .001]); 103 individuals with prior COVID-19 (30.3%) and 91 individuals without prior COVID-19 (21.0%) had some degree of dysfunction (odds ratio, 1.64 [95% CI, 1.18-2.27]).

The SARS-CoV-2 variant present at the time of infection was associated with smell outcomes; individuals with original untyped and Alpha variant infections exhibited more loss than those with other variant infections; for example, total to severe loss occurred in 10 of 42 individuals with Alpha variant infections (23.8%) and 7 of 52 individuals with original variant infections (13.5%) compared with 12 of 434 individuals with no COVID-19 history (2.8%) (P < .001 for all).

Conclusions and Relevance In this study, taste dysfunction as measured objectively was absent 1 year after exposure to COVID-19 while some smell loss remained in nearly one-third of individuals with this exposure, likely explaining taste complaints of many individuals with post–COVID-19 condition. Infection with earlier untyped and Alpha variants was associated with the greatest degree of smell loss.


Press coverage:
https://www.medpagetoday.com/neurology/longcovid/109802

 

[rvallee]

In this cross-sectional study of 340 individuals with and 434 individuals without prior COVID-19, taste function did not differ between individuals who had contracted COVID-19 one year earlier and those who had not, whereas some olfactory dysfunction was present in 30.3% of individuals with prior COVID-19 but only 21.0% of individuals with no history of infection

This contradicts a huge number of people who report otherwise. Way too many people have had altered taste perception that this can only be explained by bad methodology.

I think we're really seeing a wall that medicine has hit in terms of instruments and methods. They're completely inadequate here, but medicine is systematically making the mistake of ignoring the real world and holding on to their models. But they're oblivious to this because they only know what their models, through flawed methods and instruments, tell them.

 

[EndME]

This contradicts a huge number of people who report otherwise. Way too many people have had altered taste perception that this can only be explained by bad methodology.

I don't necessarily think so. I've only heard of few people whose taste dysfunction lasted longer than a year. A few weeks and several months was extremely common, but I think over a year is far less common or at least uncommon enough to not be picked up as statistically significantly in a sample size of 340 individuals.

Anecdotally olfactory dysfunction seems to be longer-lasting and that is also what this study picked up.

I've also heard some interesting stories of some people for whom only extremely specific ingredients all of a sudden tasted different and this lasted for multiple years and I don't think the WETT would even be able to pick that up, but I also don't think that's really a phenomenon that should be studied at length when debilitating symptoms are understudied. Given that far more interesting studies such as Long-Term Dysfunction of Taste Papillae in SARS-CoV-2 had been published a long-time ago, I don't think anybody has much reason to think this study is particularly interesting to begin with.

Other than that the study likely has its methodological flaws, starting of with the recruitment happening via Reddit and there being little certainty whether the never infected group actually is a never infected group. But I wouldn't be too suprised if in a small sample size you won't find someone with taste dysfunction, classified by the WETT, lasting over a year.