Demographics and clinical factors appear to be associated with survival in patients with Parkinson disease (PD), and the presence of dementia is associated with a significant increase in mortality, according to a report in the January issue of Archives of Neurology.
Although Parkinson disease is a common neurodegenerative disease among the elderly, there are conflicting data on the survival rates of patients with this disease, according to background information in the article.
Allison W. Willis, M.D., from Washington University School of Medicine, St. Louis, and colleagues conducted a nationwide retrospective cohort study of 138,000 Medicare beneficiaries with incident Parkinson disease who were identified in 2002 and followed up through 2008.
Sex and race "significantly predicted" survival, the researchers note. Patients who were women, Hispanic or Asian had a lower adjusted risk of death than white men. During the six-year study, 64 percent of patients with Parkinson disease died, with black patients having the highest crude death rate (66.4 percent), followed by white patients (64.6 percent), Hispanics (55.4 percent) and Asian patients (50.8 percent).
Dementia was diagnosed in 69.6 percent of the study population by the end of the study period and the highest frequency was found in black patients (78.2 percent) followed by Hispanics (73.1 percent). White and Asian patients with PD had lower, similar rates of dementia at 69 percent and 66.8 percent, respectively.
Patients with Parkinson disease and dementia had a greater likelihood of death than those without dementia. The researchers also note that patients with terminal Parkinson disease were hospitalized frequently for cardiovascular disease and infection but rarely for Parkinson disease. They also suggest Parkinson patients living in urban high industrial metal emission areas had a slightly higher adjusted risk of death, but researchers suggest more work is needed to understand if environmental exposures can influence the course of Parkinson disease or survival.
"We demonstrate that dementia occurs commonly in patients with incident PD 65 years and older; this had the strongest effect on age-adjusted survival among the variables that we studied," the authors conclude. "Our data highlight the need for prevention of or treatment for dementia in patients with PD because of its effect on survival," the authors conclude.
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Arch Neurol. Published online January 2, 2012. doi:10.1001/archneurol.2011.2370