Marked Increase in Alzheimer's Disease Identified in Medicare Claims Records Between 1991 and 1999

We linked Medicare claims data to information on 417 patients with a clinical diagnosis of Alzheimer's disease in the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) to determine what proportion of them were identified as having Alzheimer's disease (AD) in Medicare claims records. Seventy-nine percent of these patients were identified as having AD using 5 years of claims data; 87% were identified as demented when a broader set of ICD-9-CM codes was used. An Anderson-Gill counting process approach was used to model the "hazard" of patients being identified as having AD in Medicare claims data. CERAD patients with mild dementia were less likely to be identified in the claims data as having AD. Once identified in Medicare claims as having AD, patients were more likely to be so identified again. When using only the physician supplier and institutional outpatient files, approximately 75% of CERAD patients were identified as having AD; hospital files used alone identified less than one-third (29%) of the CERAD patients as having AD. The data indicate that at least 3 consecutive years of physician supplier and physician outpatient claim files should be used to identify Medicare beneficiaries with AD using Medicare claims.

Rates of dementia may vary among ethnoracial groups. Any real and substantial such difference would merit serious attention by health planners, clinicians and those seeking to advance our understanding of the etiology of this group of disorders. Randomly selected elderly persons from each of three ethnoracial groups (Latinos, African-Americans, non-Latino Whites) residing in a geographic area of northern Manhattan in New York City were screened for dementia and assessed with respect to functioning in daily tasks and other qualities of life. Systematic samples of each group were clinically evaluated for presence and subtype of dementia. Subjects were reassessed at an average of 18 months following the baseline interview. Age-specific prevalence of dementia was found to be higher in Latinos and African-Americans than in non-Latino Whites; incidence rates were consistent with this finding. Ethnoracial groups did not vary in the proportion of dementias diagnosed as Alzheimer's disease. Prevalence differences between ethnoracial groups remained consistent as diagnostic criteria were varied in breadth and when the possible mislabelling of depression was taken into account. However, level of education was strongly associated with rates of dementia and, when age and education were simultaneously controlled, the ethnoracial differences in rates were not consistently found. Planning for the wide range of services necessary for care of those suffering from dementia should take into account ethnoracial differences in rates. The higher rates found in Latino and African-American groups, relative to non-Latino Whites, are associated with clear and substantial functional dependencies and hence have important implications for qualities of life and service needs. Copyright 1999 John Wiley & Sons, Ltd.