How often is Parkinson's disease fatal?

It is not fatal. It is progressive at different speeds, some very slowly, some fast within a year for example--they end up being immobile and rigid--die of aspiration pneumonia, because in parkinson the muscles of the throat also do not work like the rest of the body.
Invariable. By far the majority of cases are age related and most occur after age 65. Most patients have accumulated significant and profound disability by 10-15 yrs, and around 70% also have a dementia. Falling and infections create additional risk, and even demise. Hard to avoid the co-morbidities of aging such as heart attacks and stokes. So, parkinson's has no cure, so far, and does shorten life.

Related Questions

How could parkinson disease be prevented?

Parkinson. Despite a good deal of investigation so far there is no known causes of Parkinson's except for those drug induced. So until the source is found the concept of prevention remains remote. Read more...

Are there any treatment that works for parkinson disease?

Surgical? Essentially there are medications and surgery. Surgical treatment would likely consist of deep brain stimulation or dbs but, you should confirm this with a neurologist and a neurosurgeon. Read more...