Clinical prognostic indicators in multiple system atrophy

Multiple system atrophy (MSA) is a neurodegenerative condition causing parkinsonism, cerebellar ataxia and/or dysautonomia. Typical survival is between 6-10 years, but some people die before five or after 15 years. This heterogeneity complicates advanced planning and clinical trial stratification. MSA prognostication studies have shown conflicting results, possibly due to diagnostic accuracy or study size. We report results from a study of survival prognostic factors in a cohort of 555 MSA patients (including the largest post-mortem confirmed cohort to date of 254 people) gathered through the Queen Square Brain Bank and the PROSPECT-M-UK multi-centre prospective cohort study. Through PROSPECT-M-UK, 318 clinically diagnosed MSA patients (17 overlapped with the QSBB cohort) were followed up annually over 5 years. The QSBB cohort clinical data was collected through retrospective review of primary and secondary care documentation. Survival analysis was performed using counting process Cox proportionate hazards modelling, Kaplan-Meier log-rank testing and landmark survival analysis to account for guarantee-time bias. Mean onset age in the combined cohort was 58.7±9.0y with median survival of 8.25y (95% CI:7.88-8.63). 28.8% were clinically diagnosed in-life with MSA-P, 23.8% MSA-C, 40.2% mixed and the rest as non-MSA diagnoses. Later disease onset was associated with shorter survival (HR=1.04, P