Modeling the effect of Alzheimer's disease on mortality

Elizabeth Johnson, Ron Brookmeyer, Kathryn Ziegler-Graham

Research output: Contribution to journalArticlepeer-review

Abstract

Mortality rate ratios and the associated proportional hazards models have been used to summarize the effect of Alzheimer's disease on longevity. However, the mortality rate ratios vary by age and therefore do not provide a simple parsimonious summary of the effect of the disease on lifespan. Instead, we propose a new parameter that is defined by an additive multistate model. The proposed multistate model accounts for different stages of disease progression. The underlying assumption of the model is that the effect of disease on mortality is to add a constant amount to death rates once the disease progresses from an early to late stage. We explored the properties of the proposed model; in particular the behavior of the mortality rate ratio and median survival that is induced by the model. We combined information from several data sources to estimate the parameter in our model. We found that the effect of Alzheimer's disease on longevity is to increase the absolute annual risk of death by about 8% once a person progressed to late stage disease. Most importantly, we find that this additive effect is the same regardless of the patients' age or gender. Thus, the proposed additive multi-state model provides a parsimonious and clinically interpretable description of the effects of Alzheimer's disease on mortality.

Original languageEnglish (US)
Article number13
JournalInternational Journal of Biostatistics
Volume3
Issue number1
DOIs
StatePublished - Jan 1 2007

Keywords

  • Alzheimer's
  • Mortality
  • Multi-state
  • Survival

ASJC Scopus subject areas

  • Statistics and Probability
  • Statistics, Probability and Uncertainty

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