Olfactory dysfunction as an early predictor for post‐COVID condition at 1‐year follow‐up

Abstract

Abstract Background Olfactory dysfunction together with neurological and cognitive symptoms are common after COVID‐19. We aimed to study whether performance on olfactory and neuropsychological tests following infection predict post‐COVID condition (PCC), persisting symptoms, and reduced health‐related quality of life. Methods Both hospitalized (N = 10) and non‐hospitalized individuals (N = 56) were enrolled in this prospective cohort study. Participants were evaluated 1–3 months after infection with an olfactory threshold test and neuropsychological tests, which was used as predictors of PCC. A questionnaire outlining persisting symptoms and the validated instrument EuroQol five‐dimension five‐level for health‐related quality of life assessment were used as outcome data 1 year after infection (N = 59). Principal component analysis was used to identify relevant predictors for PCC at 1 year. Results Objectively assessed olfactory dysfunction at 1–3 months post infection, but not subjective olfactory symptoms, predicted post‐COVID condition with reduced health‐related quality of life (PCC+) at 1 year. The PCC+ group scored more often below the cut off for mild cognitive impairment on the Montreal Cognitive Assessment (61.5% vs. 21.7%) and higher on the Multidimensional Fatigue Inventory‐20, compared to the group without PCC+. Conclusion Our results indicate that objectively assessed, olfactory dysfunction is a predictor for PCC+. These findings underscore the importance of objective olfactory testing. We propose that olfactory screening in the early post‐acute phase of COVID‐19 infection might identify individuals that are at higher risk of developing long‐term health sequalae.

Keywords

• COVID‐19
• health‐related quality of life
• long covid
• olfactory dysfunction
• post‐COVID condition (PCC)