title: Cognitively-Related Basic Activities of Daily Living Impairment Greatly Increases the Risk of Death in Alzheimers Disease.
abstract: BACKGROUND
  Some Alzheimer's disease (AD) patients die without ever developing cognitively impaired basic activities of daily living (basic ADL), which may reflect slower disease progression or better compensatory mechanisms. Although impaired basic ADL is related to disease severity, it may exert an independent risk for death. This study examined the association between impaired basic ADL and survival of AD patients, and proposed a multistate approach for modeling the time to death for patients who demonstrate different patterns of progression of AD that do or do not include basic ADL impairment.
  
  
  METHODS
  1029 patients with probable AD at the Baylor College of Medicine Alzheimer's Disease and Memory Disorders Center met the criteria for this study. Two complementary definitions were used to define development of basic ADL impairment using the Physical Self-Maintenance Scale score. A weighted Cox regression model, including a time-dependent covariate (development of basic ADL impairment), and a multistate survival model were applied to examine the effect of basic ADL impairment on survival.
  
  
  RESULTS
  As expected decreased ability to perform basic ADL at baseline, age at initial visit, years of education, and sex were all associated with significantly higher mortality risk. In those unimpaired at baseline, the development of basic ADL impairment was also associated with a much greater risk of death (hazard ratios 1.77-4.06) over and above the risk conferred by loss of MMSE points. A multi-state Cox model, controlling for those other variables quantified the substantive increase in hazard ratios for death conferred by the development of basic ADL impairment by two definitions and can be applied to calculate the short term risk of mortality in individual patients.
  
  
  CONCLUSIONS
  The current study demonstrates that the presence of basic ADL impairment or the development of such impairments are important predictors of death in AD patients, regardless of severity.
authors: Department of Public Health, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No.1, University Road, Tainan City 701, Taiwan.
authors: Fu-Wen
authors: FW
authors: Liang
authors: Department of Biostatistics, University of Texas-Health Science Center at Houston, 1200 Pressler Street, E827, Houston, Texas 77030, United States of America.
authors: Wenyaw
authors: W
authors: Chan
authors: Department of Geriatrics and Gerontology, Chi-Mei Medical Center, 901, Zhong-Hua Rd., Yong-Kang Dist., Tainan City 710, Taiwan.
authors: Ping-Jen
authors: PJ
authors: Chen
authors: Department of Psychology, Rice University, 6100 Main MS-27, Houston, Texas 77005, United States of America.
authors: Carissa
authors: C
authors: Zimmerman
authors: Essentia Institute of Rural Health, 502 East Second Street, Duluth, MN 55805, United States of America.
authors: Stephen
authors: S
authors: Waring
authors: Alzheimer's Disease and Memory Disorders Center, Baylor College of Medicine,7200 Cambridge Street, A9.210, Houston, Texas 77030, United States of America.
authors: Rachelle
authors: R
authors: Doody
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000401:mortality* / Q000503:physiopathology*; D003072:Cognition Disorders / Q000401:mortality / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors