Survival analysis and prognostic nomogram model for multiple system atrophy

Objective: The purpose of our study was to explore the factors associated with the survival of multiple system atrophy (MSA) patients and to produce a prognostic nomogram to predict survival in an individual MSA patient. Methods: 220 probable MSA patients were included from 2009 to 2013. Disease severity was measured by the Unified Multiple System Atrophy Rating Scale (UMSARS). The univariate and multivariable Cox regression analyses were used to identify factors associated with survival in MSA patients. A nomogram model predicting the probability of survival was formulated based on the results of the multivariate Cox analysis. The results were validated using bootstrap resampling and a prospective study on 80 patients included from January 2014 to August 2015 at the same institution. Results: Median survival from symptom onset to death was 6.4 years (95%CI = 6.1-6.7). The multivariate Cox survival model suggested that autonomic onset, higher UMSARS score, frequent falls, orthostatic hypotension (OH) and shorter diagnostic delay were associated with poor survival. The nomogram model for the multivariate Cox survival model had a concordance index of 0.677 in primary cohort, which showed a concordance index of 0.721 in validation cohort. Conclusion: Autonomic onset, higher UMSARS score, frequent falls, OH and shorter diagnostic delay at baseline were independent markers for poor survival in MSA. The prognostic nomogram model created by the significant independent factors for longer survival provided an effective way to predict the probability of longer survival in an individual MSA patient.