title: Interactive Effects of Dementia Severity and Comorbidities on Medicare Expenditures.
abstract: Few studies have examined how dementia and comorbidities may interact to affect healthcare expenditures.
  
  
  
  To examine whether effects of dementia severity on Medicare expenditures differed for individuals with different levels of comorbidities.
  
  
  
  Data are drawn from the Washington Heights-Inwood Columbia Aging Project (WHICAP). Comprehensive clinical assessments of dementia severity were systematically carried out at ∼18 month intervals. Dementia severity was measured by Clinical Dementia Rating (CDR). Comorbidities were measured by a modified Elixhauser comorbidities index. Generalized linear models examined effects of dementia severity, comorbidities, and their interactions on Medicare expenditures (1999-2010).
  
  
  
  At baseline, 1,280 subjects were dementia free (CDR = 0, 66.4%), 490 had very mild dementia (CDR = 0.5, 25.4%), 108 had mild dementia (CDR = 1, 5.6%), and 49 had moderate/severe dementia (CDR = 2/3, 2.5%). Average annual Medicare expenditures for individuals with moderate/severe dementia were more than twice as high as those who were dementia free (CDR = 0: $9,108, CDR = 0.5/1: $11,664, CDR≥2: $19,604, p < 0.01). Expenditures were approximately 10 times higher among those with≥3 comorbidities than among those with no comorbidities ($2,612 for those with no comorbidities, to $6,109 for those with 1, $10,656 for those with 2, and $30,244 for those with≥3 comorbidities, p < 0.001). Dementia severity was associated with higher expenditures, but comorbidities were the most important predictor of expenditures. We did not find strong interaction effects between number of comorbidities and dementia severity.
  
  
  
  Increasing dementia severity and higher comorbidities are associated with higher Medicare expenditures. Care of individuals with dementia should focus on management of comorbidities.
authors.affiliation: Department of Geriatrics and Palliative Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.|James J Peters VA Medical Center, Bronx, NY, USA.
authors.forename: Carolyn W
authors.initials: CW
authors.lastname: Zhu
authors.affiliation: Cognitive Neuroscience Division of the Department of Neurology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Cosentino
authors.affiliation: Department of Geriatrics and Palliative Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Ornstein
authors.affiliation: Cognitive Neuroscience Division of the Department of Neurology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY, USA.
authors.forename: Yian
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Howard
authors.initials: H
authors.lastname: Andrews
authors.affiliation: Cognitive Neuroscience Division of the Department of Neurology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY, USA.
authors.forename: Yaakov
authors.initials: Y
authors.lastname: Stern
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D003704:Dementia / Q000150:complications* / Q000191:economics* / Q000453:epidemiology / Q000628:therapy; D005260:Female; D005102:Health Expenditures; D006801:Humans; D016014:Linear Models; D008297:Male; D006278:Medicare / Q000191:economics*; D011446:Prospective Studies; D012044:Regression Analysis; D012720:Severity of Illness Index; D014481:United States
keywords: Health expenditure; Medicare; comorbidities; economics; longitudinal analysis