The charts provide an analysis of the status of olfactory disturbances across four consecutive visits, and a comparison between two distinct cohorts.
Overall, the number of P1 and P2 participants diagnosed with anosmia and hyposmia decreased over a four-phase examination, while the number of participants with parosmia and normosmia exhibited an opposite trend. Additionally, at the initial visit, hyposmia constituted the largest proportion in both groups; however, by the final assessment, the majority of participants in both cohorts were reported to have recovered to normosmia. These data indicate that the proportion of patients with hyposmia decreased over time as many individuals gradually recovered their sense of smell, leading to an increase in the number of participants with normosmia at subsequent visits.
Regarding the conditions that exhibited a decrease, hyposmia experienced the most significant decline. During the initial visit, hyposmia was primarily a concern among two groups of patients, with more than three-quarters of the individuals in the P1 group and half of the patients in the P2 group affected. The proportion of both P1 and P2 cohorts continued to decrease significantly, reaching 19.5% and 14.8%, respectively, in the third examination. During the most recent inspection, the number of patients experiencing hyposmia in both the P1 and P2 groups decreased significantly, with reported prevalence rates of 3.4% and 2.6%, respectively. Furthermore, concerning the initial variant of COVID-19, a decrease in the prevalence of anosmia among patients was observed. At the commencement of the observation period, the proportion of participants in both groups constituted only a small fraction. After three subsequent visits, all P1 and P2 participants experienced an improvement; no patients developed anosmia compared to the initial examination. According to the reference scales, the prevalence of patients with hyposmia significantly decreased, while instances of anosmia completely resolved, as most participants gradually recovered normal olfactory function over time.
Regarding the other symptoms that increased, the prevalence of normosmia rose sharply during the period examined, starting from no reported cases at the initial visit to a significant increase by the third assessment, with 10.3% of patients in P1 and 58.3% in P2. Following the most recent assessment, this percentage increased significantly in both the P1 and P2 cohorts, with 77% and 93% of patients, respectively, regaining normosmia. Parosmia was the only olfactory disturbance that exhibited a fluctuation, with only a small fraction of patients in both groups affected. However, during the second visit, the figures increased dramatically in both P1 and P2, reaching 94.3% and 67.8%, respectively. Subsequently, the prevalence of parosmia among patients declined rapidly until the final assessment, reaching 19.5% in group P1 and 4.2% in group P2. This analysis indicates that the sharp rise in normosmia was primarily attributable to the gradual recovery of patients’ olfactory function, whereas the temporary increase in parosmia manifested as a transitional stage of olfactory distortion during recovery, eventually subsiding by the final visit.