The elevated risk of death for patients with clinically diagnosed synucleinopathies and symptoms of parkinsonism is highest for those with multiple system atrophy with predominant parkinsonism (MSA-p), followed by dementia with Lewy bodies (DLB), Parkinson’s disease dementia (PDD), and Parkinson’s disease (PD), according to Rodolfo Savica, MD, PhD, and his associates.

The investigators compared 461 patients who had onset of a clinically presumed synucleinopathy manifesting as parkinsonism from 1991 to 2010 with 452 age- and sex-matched referent participants from the general population who were free of parkinsonism and tremor of any type in the year of onset of the other patients’ synucleinopathies. Of the 461 patients with the presumed synucleinopathies, 316 (68.6%) died during follow-up and 311 had a known cause of death (98.4%). Of the 452 referent participants, 220 (48.7%) died during follow-up and 216 had a known cause of death (98.2%). The highest risk of death was among patients with MSA-p (hazard ratio, 10.51) when compared with referent participants. The remaining patients also had elevated risk of death: DLB (HR, 3.94), PDD (HR, 3.86), and PD (HR, 1.75).

Neurodegenerative disease was the most frequent cause of death among patients for all synucleinopathies (31.5%) and in PD alone (25.6%), and cardiovascular events were the second most common cause of death (15.7%). Among the referent participants, cardiovascular events were the most common cause of death (25.5%).

The results were consistent with the causes of death observed among patients with DLB, PDD, and MSA-p; however, the researchers said the sample size was too limited to observe a sufficient number of events. They also noted that there was no significant interaction with sex and age in predicting survival rates for any type of synucleinopathy.

“Our findings contribute important new evidence about the natural history and survival of people affected by synucleinopathies of various types,” the researchers concluded. “Our results may be helpful to guide clinicians counseling patients and caregivers.”

Find the full study in JAMA Neurology ( doi: 10.1001/jamaneurol.2017.0603 ).