Recovery of Parosmia Preferentially Influences Longitudinal Improvement of Quality of Life in C19OD

BACKGROUND: Persistent COVID-associated olfactory dysfunction (C19OD) negatively impacts quality of life (QoL). This prospective longitudinal cohort study sought to determine which aspects of chemosensory recovery may preferentially influence QoL improvement in this population. METHODS: Individuals with C19OD (N = 100) completed chemosensory and QoL assessment with Sniffin' Sticks, Taste Assessment, Questionnaire of Olfactory Disorders-Negative Statements (QOD-NS), and QOD-PAR at baseline and 1 year. Multivariable analyses assessed baseline and longitudinal associations between chemosensory dysfunction and QOD-NS. RESULTS: QoL associated with TDI (Coef.; [CI]; p-value: -0.32; [-0.62, -0.032]; 0.030), threshold (-0.82; [-1.5, -0.14]; 0.019), QOD-Par (-1.0; [-0.20, -1.9]; 0.016), and self-reported gustatory dysfunction (GD) (-7.4; [-14, -0.46]; 0.037) at baseline assessment, though quantitative GD did not associate with QoL. Longitudinally, improvements in discrimination (-1.2; [-2.3, -0.18]; 0.023) and QOD-Par (-2.5; [-0.99, -4.1]; 0.002) scores were associated with improved QoL. Individuals with improved parosmia symptoms experienced a 12.86 (12.99, 0.040) QOD-NS point improvement from baseline compared to 5.91 (7.98, < 0.001) for those with persistent parosmia. CONCLUSIONS: Independent of mental health, chemosensory function independently drives QoL in C19OD. Parosmia, low odor threshold, and patient-reported GD are all associated with poorer QoL at baseline. Longitudinally, the ability to differentiate among odors is an important correlate of improvement of smell-related QoL in C19OD patients, while parosmia is the strongest driver of longitudinal recovery of smell-related QoL in C19OD. Trending domain-specific olfactory performance in C19OD may allow for improved patient counseling and QoL prognosis.