Odour discrimination and identification as a biomarker of long-term disability worsening in multiple sclerosis.
Mult Scler 2024;
30:55-62. [PMID:
37850472 PMCID:
PMC10782652 DOI:
10.1177/13524585231201093]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 08/06/2023] [Accepted: 08/23/2023] [Indexed: 10/19/2023]
Abstract
BACKGROUND
Odour discrimination and identification (DI) are markers associated with disability worsening and neuroaxonal damage in multiple sclerosis (MS).
OBJECTIVE
The main objective of this research is to investigate whether longitudinal change of DI predicts long-term MS disease course.
METHODS
This is a 6-year prospective longitudinal study on MS patients at the MS Clinic Innsbruck. Clinical, bi-annual visits assessed patients' history and Expanded Disability Status Scale (EDSS) score. DI and cognitive function were assessed at baseline (BL), Year 1 (Y1), Year 2 (Y2) and Year 6 (Y6) by the 'Sniffin' Sticks'/Symbol Digit Modalities Test.
RESULTS
Around 92 of 139 patients were available for Y6 follow-up. Mean DI scores significantly decreased over time (BL = 27.8, Y1 = 27.5, Y2 = 26.3 and Y6 = 26.3; p < 0.001) and negatively correlated with patients' age (rs = -0.120, p = 0.032) and disease duration (rs = -0.103, p = 0.041). Multivariable regression analyses revealed that lower absolute DI scores and larger DI score loss over time were associated with higher probability of EDSS worsening (per -1 point: hazard ratio (HR) = 1.40 (1.16-1.68) and 2.34 (1.27-4.21)), progression independent of relapse activity (PIRA) (HR = 1.49 (1.20-1.85) and 2.22 (1.33-3.31)) and cognitive deterioration (HR = 1.75 (1.35-2.27) and 4.29 (1.26-2.84)) at Y6, but not with time to first relapse.
CONCLUSION
Odour DI is an irreversible marker of neuroaxonal damage, associated with PIRA, cognitive deterioration and EDSS worsening.
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