Long-term cognitive decline in older subjects was not attributable to noncardiac surgery or major illness.
BACKGROUND
Persistent postoperative cognitive decline is thought to be a public health problem, but its severity may have been overestimated because of limitations in statistical methodology. This study assessed whether long-term cognitive decline occurred after surgery or illness by using an innovative approach and including participants with early Alzheimer disease to overcome some limitations.


METHODS
In this retrospective cohort study, three groups were identified from participants tested annually at the Washington University Alzheimer's Disease Research Center in St. Louis, Missouri: those with noncardiac surgery, illness, or neither. This enabled long-term tracking of cognitive function before and after surgery and illness. The effect of surgery and illness on longitudinal cognitive course was analyzed using a general linear mixed effects model. For participants without initial dementia, time to dementia onset was analyzed using sequential Cox proportional hazards regression.


RESULTS
Of the 575 participants, 214 were nondemented and 361 had very mild or mild dementia at enrollment. Cognitive trajectories did not differ among the three groups (surgery, illness, control), although demented participants declined more markedly than nondemented participants. Of the initially nondemented participants, 23% progressed to a clinical dementia rating greater than zero, but this was not more common after surgery or illness.


CONCLUSIONS
The study did not detect long-term cognitive decline independently attributable to surgery or illness, nor were these events associated with accelerated progression to dementia. The decision to proceed with surgery in elderly people, including those with early Alzheimer disease, may be made without factoring in the specter of persistent cognitive deterioration.
Cardiothoracic Anesthesiology and Cardiothoracic Intensive Care, Department of Anesthesiology, Washington University in St. Louis, Missouri 63110-1093, USA. avidanm@wustl.edu
Michael S
MS
Avidan
Adam C
AC
Searleman
Martha
M
Storandt
Kara
K
Barnett
Andrea
A
Vannucci
Leif
L
Saager
Chengjie
C
Xiong
Elizabeth A
EA
Grant
Dagmar
D
Kaiser
John C
JC
Morris
Alex S
AS
Evers
D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000209:etiology*; D015331:Cohort Studies; D003704:Dementia / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000209:etiology*; D012189:Retrospective Studies