Assessment of patient recognition of coronavirus disease 2019 (COVID‐19)‐associated olfactory loss and recovery: a longitudinal study

Prajapati, Divya P.; Shahrvini, Bita; Said, Mena; Srinivas, Shanmukha; DeConde, Adam S.; Yan, Carol H.

BACKGROUND: The clinical course of coronavirus disease 2019 (COVID‐19) olfactory dysfunction remains poorly characterized, often limited by self‐reported measures. Given the logistical challenges of psychophysical testing, understanding the longitudinal relationship between self‐reported and quantitative measures can help accurately identify patients with persistent olfactory dysfunction. This study aimed to longitudinally correlate measured and subjective olfactory function in COVID‐19 subjects. METHODS: A prospective, longitudinal study evaluating subjective and measured olfaction was conducted on ambulatory COVID‐19 subjects. Olfaction scores were obtained using a visual analogue scale (VAS) (0 = anosmia, 10 = normosmia) and the validated 12‐item Brief Smell Identification Test (BSIT). Weekly testing was performed until recovery (BSIT ≥ 9/12 and/or VAS = 10/10) or study completion. RESULTS: Eighty‐six polymerase chain reaction (PCR)‐positive COVID‐19 subjects were recruited ≤3 days from diagnosis and 52 completed longitudinal testing. Among those with self‐reported smell loss at recruitment, similar levels (75.8%) of objective (BSIT ≥ 9/12) and subjective recovery were obtained using a VAS cutoff ≥8, yet only 30.3% reported complete subjective recovery (VAS = 10). Median times to objective and complete subjective olfactory recovery were 12 ± 2.3 and 24 ± 3.5 days, respectively. Although both measures showed chemosensory improvement, the distributions of objective and full subjective olfactory recovery differed significantly (log rank test χ(2) = 6.46, degrees of freedom [df] = 1, p = 0.011). Overall correlation between BSIT and VAS scores was moderate to strong across longitudinal follow‐up (r (s) = 0.41–0.65). CONCLUSION: Self‐reported and psychophysically measured COVID‐19 olfactory dysfunction improve at similar levels and are moderately correlated longitudinally, yet there is a significant delay in complete subjective recovery. Psychophysical testing in conjunction with qualitative assessments may be considered for counseling and follow‐up of patients with COVID‐19 smell loss.