Cognitive scores, even within the normal range, predict death and institutionalization.
BACKGROUND
Dementia is a predictor of death and institutionalization. It is less clear if variations in cognition within the normal range predict adverse outcomes.


OBJECTIVE
To determine if variation at the high end of cognitive test scores predicts mortality or institutionalization, independent of the effect of potential confounders.


METHODS
Secondary analysis of the Canadian Study of Health and Aging, a population-based longitudinal study with an initial data collection in 1991 and follow-up five years later.


METHODS
Community-dwelling seniors living in Canada.


METHODS
9008 consenting seniors were sampled from representative population registries in Canada.


METHODS
Age, gender, marital status, the Mini-Mental State Examination, self-rated health, and activities of daily living.


RESULTS
Death or institutionalization over the five years of follow-up.


RESULTS
Mini-Mental State Examination scores predicted mortality and institutionalization. The unadjusted odds ratio of mortality was 0.85 (95% confidence interval 0.84, 0.86) per point on the Mini-Mental State Examination, and the adjusted odds ratio was 0.95 (95% confidence interval 0.93, 0.97). The unadjusted odds ratio for institutionalization was 0.83 (95% confidence interval 0.82, 0.85), and the adjusted odds ratio was 0.91 (95% confidence interval 0.90, 0.94). This effect was present even in analyses restricted to those within the normal range of Time 1 Mini-Mental State Examination scores.


CONCLUSIONS
Low normal cognitive test scores predict adverse outcomes. Clinicians should consider close clinical follow-up of those with low normal cognitive test scores. Further research is needed to target seniors for follow-up and possible intervention to decrease mortality and institutionalization risk.
St John
Philip D
PD
University of Manitoba, Health Sciences Centre, GE545-820 Sherbrook Street, Winnipeg, MB R3A 1R9, Canada. pstjohn@exchange.hsc.mb.ca
Montgomery
Patrick R
PR
Kristjansson
Betsy
B
McDowell
Ian
I
D000368:Aged; D000369:Aged, 80 and over; D002170:Canada; D003071:Cognition / Q000502:physiology*; D003704:Dementia / Q000401:mortality; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007326:Institutionalization / Q000706:statistics & numerical data*; D007361:Intelligence Tests / Q000706:statistics & numerical data*; D008137:Longitudinal Studies; D008297:Male; D015233:Models, Statistical; D009026:Mortality / Q000639:trends*; D017063:Outcome Assessment, Health Care; D011237:Predictive Value of Tests; D012016:Reference Values