Prognostic value of odor identification impairment in multiple sclerosis: 10-Years follow-up

Background: Olfactory dysfunction has been linked to clinical severity variables in multiple MS populations. Though, its prognostic value is still unknown.

Objective: The aim of this study was to explore the long-term outcome associated with Brief-Smell Identification Test (B-SIT) performance in a cohort of MS patients.

Methods: A retrospective review of the clinical records was conducted in 149 patients who participated in a previous study, with a median follow-up of 121 months. Demographic and clinical data regarding the last clinical appointment with EDSS measurement were collected. Multiple Sclerosis Severity Scale (MSSS) and Age-Related Multiple Sclerosis Severity (ARMSS) scores were calculated. Date of the last clinical contact or death was recorded.

Results: Among MS patients with progressive clinical course (n = 33), those with impaired B-SIT at baseline had greater change per month during follow-up (as measured by increases in MSSS and ARMSS scores) and a higher hazard of death. No significant associations were found among patients with relapsing and remitting MS (n = 116).

Conclusions: The study results demonstrate that odor identification impairment has prognostic value in progressive MS, suggesting that a brief odor identification measure can be a marker of neurodegeneration in progressive MS.