Nearly two-thirds of adults with prior SARS-CoV-2 infection had measurable hyposmia on formal testing despite not reporting changes in smell, according to the NIH-funded RECOVER-Adult cohort. Among 1,393 participants who did report loss or change of smell or taste, nearly 80% had abnormal University of Pennsylvania Smell Identification Test scores, and 23% met criteria for severe microsmia or anosmia.
Overall, 2,956 previously infected participants were tested a mean of 1.8 years postinfection. Those with self-reported smell loss scored at the 16th percentile of University of Pennsylvania Smell Identification Test (UPSIT) performance versus the 23rd percentile in infected patients without reported loss and the 28th percentile in uninfected controls. Notably, 8% of infected individuals without reported changes showed severe deficits. Younger women were disproportionately affected, performing below historical norms.
Cognitive symptoms were common, reported by 66% of infected individuals with smell loss compared with 33% without. Rates were slightly higher in those with abnormal UPSIT scores (67%) than in those with normal scores (64%). Neuro-QoL testing, conducted only in participants with cognitive complaints, placed mean performance in the 12th to 14th percentile nationally.
Smell loss patterns varied: clustering identified subgroups with selective loss of citrus, turpentine, or other specific odors, and others with widespread deficits including fruit punch and bubble gum.
Limitations included absence of phantosmia and taste assessments, potential misclassification of asymptomatic infection in controls, and Neuro-QoL data limited to symptomatic participants. Still, "given the degree of hyposmia in persons previously infected, formal olfactory testing may be beneficial in standard postinfection care," concluded Leora I. Horwitz, MD, MHS, Department of Population Health, NYU Grossman School of Medicine, and colleagues.
The study was funded by the NIH RECOVER Initiative. The authors’ disclosures can be found in the published study.
Source: JAMA Network Open
