Prevalence of parkinsonian signs and associated mortality in a community population of older people.

Background: Older people frequently have signs of parkinsonism, but information about the prevalence of parkinsonism and mortality among those with the condition in the community is limited.
Methods: A stratified random sample of 467 residents of East Boston, Massachusetts, 65 years of age or older, were given structured neurologic examinations. Using uniform, specified combinations of parkinsonian signs, we estimated the prevalence of four categories of signs--bradykinesia, gait disturbance, rigidity, and tremor--and of parkinsonism, defined as the presence of two or more categories. We did not study Parkinson's disease because it could not be distinguished from other conditions that can cause parkinsonism. Proportional-hazards models were used to compare the risk of death among people with and those without parkinsonism.
Results: One hundred fifty-nine persons had parkinsonism, 301 did not, and 7 could not be classified. The overall prevalence estimates were 14.9 percent for people 65 to 74 years of age, 29.5 percent for those 75 to 84, and 52.4 percent for those 85 and older. With a mean follow-up period of 9.2 years, 124 persons with parkinsonism (78 percent) and 146 persons without (49 percent) died. Adjusted for age and sex, the overall risk of death among people with parkinsonism was 2.0 (95 percent confidence interval, 1.6 to 2.6) times that among people without. Among people with parkinsonism, the presence of gait disturbance was associated with an increased risk of death.
Conclusions: Parkinsonism is very common among people over the age of 65, and its prevalence increases markedly with age. Parkinsonism is associated with a twofold increase in the risk of death, which is strongly related to the presence of a gait disturbance.