Early Clinical Predictors of Mortality in Parkinson Disease, Parkinsonism

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Early mild cognitive impairment is an important predictor of prognosis in Parkinson disease.
Early mild cognitive impairment is an important predictor of prognosis in Parkinson disease.

Mortality in parkinsonism highly depends upon the characteristics and type of the individual parkinsonian disorder, and patients with normal cognitive function and Parkinson disease appear to have a normal life expectancy, according to a study published in Neurology.

Researchers in this study examined mortality and associated risk factors in 182 patients diagnosed with new-onset parkinsonism from January 2004 to April 2009 in a community of 142,000 people in Sweden. They used a multimodal research protocol to follow patients for up to 13.5 years. Mortality rates in the general population were used to determine a standardized mortality ratio, and independent predictors of mortality were investigated using Cox proportional hazard models.

One hundred and nine patients died (61.2%), and the standardized mortality ratio was 1.84 (95% CI, 1.50-2.22, <.001). The highest mortality rates were in participants with atypical parkinsonism such as progressive supranuclear palsy or multiple system atrophy. Mortality rates for participants who had normal cognitive functioning at baseline were not significantly different from those seen in the general population, but mortality rates increased for patients with mild cognitive impairment (SMR: 2.17), and these patients had a 2.4 times higher hazard of death (adjusted for age) in follow-up than patients without cognitive impairment at baseline (<.001). 

Mini-Mental State Examination (MMSE) scores at baseline were also correlated with survival (1.17 times higher hazard of death after age-adjustment for each lower point, =.011). If a mean age of 71.2 years is assumed at baseline, expected survival in Parkinson disease was 11.6 years without mild cognitive impairment and 8.2 years with it. Fewer years of education and tremor were uncorrelated to survival.

Experiencing a disease phenotype comprising of mild cognitive impairment, freezing of gait, a postural imbalance and gait disorder (PIGD), onset of dementia, slowness in the Timed Up and Go (TUG) test, high disease severity, and hyposmia in the first 3 years predicted shorter survival in the univariate analysis.  Reduced dopamine transporter activity and elevated leukocytes in the cerebrospinal fluid were significantly associated with shorter survival.

Study investigators conclude "that patients with incident parkinsonism have reduced survival but that the survival is highly dependent on the type and characteristics… The finding of a low-grade immune reaction in the [cerebrospinal fluid] of patients with [Parkinson disease] who have short survival may have important clinical implications and therefore merits further investigation."

Reference

Bäckström D, Granåsen G, Domellöf ME, et al. Early predictors of mortality in parkinsonism and Parkinson disease: a population-based study [published online October 31, 2018]. Neurology. doi: 10.1212/WNL.0000000000006576

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