My thanks go to Aspergerian for pointing me at this paper from 2017:
"Association of Autonomic Dysfunction With Disease Progression and Survival in Parkinson Disease"
Association of Autonomic Dysfunction With Disease Progression and Survival in Parkinson Disease
Albeit with a small sample size, n=100, this paper takes a snap shot of PwP in the period leading up to death. Lots of interesting statistics, such as 83% had constipation and 84% had urinary problems.
John