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SUMMARY:A parametric approach to modeling changes in general health and co
 gnition: developing a stochastic model of aging - Arnold Mitnitski\, PhD\,
  Department of Medicine\, Department of Mathematics and Statistics\, Dalho
 usie University\, Halifax\, Nova Scotia\, Canada
DTSTART:20080618T120000Z
DTEND:20080618T130000Z
UID:TALK12516@talks.cam.ac.uk
CONTACT:Nikolaos Demiris
DESCRIPTION:I will discuss a novel approach which is being developed by ou
 r group at Dalhousie University\, Halifax\, to summarizing health transiti
 ons as a stochastic process of changes in health states. Instead of analyz
 ing health transitions separately in each direction (improvement\, worseni
 ng and death) we suggest a general parametric model (e.g.\, based on a Poi
 sson density function) which allows estimating the probabilities of change
 s (including adverse outcomes) as a function of the current state.\n\nThe 
 basic model has four population specific parameters\, two of which represe
 nt health transitions of survivors\; the other two represent the probabili
 ty of death. I will show how covariates can be incorporated in the model. 
 The approach is illustrated in representative Canadian populations for: (i
 ) transitions in general health status (deficits accumulation count/the fr
 ailty index)\, (ii) transitions in cognitive states (represented by the er
 rors in the Modified Mini Mental State Examination Score)\, and (iii) tran
 sitions between cognitive impairments of different degrees. The performanc
 es of the models are always very high\, R2 ranging from 0.89 to 0.99\, and
  robust across settings.\n\nI will also discuss the general stochastic mec
 hanism of organism-environment interactions\, coupled with a decrease of s
 tress-resistance\, to explain the observed patterns of how health state ch
 anges with age.  This allows an understanding the origin of health deficit
  (and similarly\, cognitive deficits) accumulation\, can be used to classi
 fy different populations. This approach has the potential for a wide range
  of applications in analyzing age-related health trajectories. 
LOCATION:Large Seminar Room\, 1st Floor\, Institute of Public Health\, Uni
 versity Forvie Site\, Robinson Way\, Cambridge
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