title: Diagnostic transitions in mild cognitive impairment by use of simple Markov models.
abstract: BACKGROUND
  Mild cognitive impairment (MCI) is a complex entity, which can involve persistence of the symptoms, conversion to dementia or improvement. The aim was to study the transitions between normal cognitive ageing and three MCI subtypes by using Markov transition models for different intervals between baseline and the follow-up assessment.
  
  
  METHODS
  A total of 294 participants over 50 years old attending primary care centres were assessed and diagnosed at baseline as multi-domain amnestic MCI (22 participants), single domain amnestic MCI (44), non-amnestic MCI (non-amnestic MCI) (26) or controls (202). We adopted an overlapping interval strategy by constructing six different mid-point time intervals according to the time between the baseline and the follow-up assessment. We used Markov transition models to study diagnostic changes in the groups in the different time intervals
  
  
  RESULTS
  The rate of change was lowest in the control group. In the single domain amnestic MCI and non-amnestic MCI groups, the same diagnosis was usually retained or changed to normal cognitive functioning. In the multi-domain amnestic MCI group, the rate of transition to normal functioning was lowest, and the conversion to dementia was the highest of all groups. The best fit to the Markov models was found for the period between 18-21 months, whereas the worst fit was for the period between 9-15 months
  
  
  CONCLUSIONS
  Markov models provide a comprehensive view of transitions between MCI and normal cognitive functioning. Time interval strategies seem to provide a good opportunity to monitor diagnostic transitions, although wider intervals including subsequent assessments are needed. The low rates of conversion to dementia are discussed.
authors.affiliation: Departament of Developmental Psychology, University de Santiago de Compostela, A Coruña, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Facal
authors.affiliation: Departament de Metodologia de les Ciències del Comportament, University of Barcelona, Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Guàrdia-Olmos
authors.affiliation: Departament of Developmental Psychology, University de Santiago de Compostela, A Coruña, Spain.
authors.forename: Onésimo
authors.initials: O
authors.lastname: Juncos-Rabadán
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000647:Amnesia / Q000175:diagnosis / Q000523:psychology; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000175:diagnosis / Q000523:psychology; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000523:psychology; D003704:Dementia / Q000175:diagnosis / Q000523:psychology; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008390:Markov Chains; D008569:Memory Disorders / Q000523:psychology; D008875:Middle Aged; D008960:Models, Psychological; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics; D012307:Risk Factors
keywords: Markov chain; diagnostic transitions; mild cognitive impairment; overlapping interval strategy