Objective: To reassess the CMSAR and determine if new criteria and new biomarkers can enhance diagnostic accuracy.

Background: The CMSAR, conducted between 2015 and 2019, included 80 Multiple System Atrophy (MSA) cases adhering to Gilman’s 2008 criteria for possible(n=40) or probable MSA-P and MSA-C. Additionally, it featured a biorepository, ensuring standardized protocols for biosample collection alongside follow-up clinical assessments.

Method: In 2022, a follow-up assessment was conducted through medical record review and telephone interviews and new criteria were retrospectively implemented. Qualitative variables were compared using Fisher’s exact test. Quantitative data were analyzed with Kruskal-Wallis or Mann-Whitney U tests. Kaplan-Meier curves were assessed using log-rank tests to detect group differences. Neurofilament (NFL) quantification in CSF was assessed by Elisa (pg/ml) in 57 cases and alpha-synuclein (a-syn) seeding was assessed by RT-QuIC in 45 cases.

Results: The revision reported 20/80 surviving cases and misdiagnosis in 12/80. At baseline, 39 fulfilled new criteria for clinically established (CE), 26 for clinically probable (CP), and 15 did not fulfill new criteria (NC). During follow-up 6/26 CP cases converted to CE diagnosis, 4/15 NC cases converted to CP (3) and CE (1). Eight NC cases and 4 CP cases were excluded due to misdiagnosis. Median NFL for all cases was 3116pg/ml. Cases with 2008 possible diagnosis at the final visit had significantly lower NFL (2318). There were no differences between CE or CP. All cases excluded as PD or ILOCA had low NFL (<1000). NC cases at baseline had significantly lower median NFL (889).  Three NC cases are suspected to have MSA and show NFL levels >1000. One CP case shows NFL of 889.  There are no differences in survival when comparing CP and CE cases in contrast to a significantly higher survival for 2008’ possible MSA cases (p<0.038). A-syn RTQUIC showed Lewy-body-like curves in 4 cases, of which 3 have NFL <1000 and have been excluded as Parkinson’s disease.

Conclusion: In conclusion, new diagnostic criteria appear more specific, particularly the CE category, but early diagnosis remains challenging, with misdiagnosis still reported. NFL and a-syn RT-QuIC show promise in aiding diagnosis or exclusion in earlier disease stages.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/catalan-msa-registry-cmsar-applying-new-clinical-criteria-and-biomarkers-for-increasing-diagnostic-accuracy-is-new-better/