The incidence of cognitive decline after (not) undergoing coronary artery bypass grafting: the impact of a controlled definition.
BACKGROUND
After coronary artery bypass grafting (CABG), 20-30% of patients are reported to suffer from cognitive decline. Studies reporting these high incidences, however, have not included an appropriate control group.


METHODS
We repeatedly administered a series of neuropsychological tests to 112 healthy middle-aged volunteers not undergoing surgery, and applied two widely used definitions of cognitive decline to their test results. In addition, we re-analysed the neuropsychological test data of 281 CABG patients with a definition of cognitive decline that takes into account the natural variability of test performance that was found in the volunteers.


RESULTS
Three months after their first assessment, 14-28% of the volunteers suffered from cognitive decline according to the definitions of cognitive decline after CABG. Using the controlled definition of cognitive decline that takes the natural variability in test performance into account, we found that only 7.7% of the CABG patients suffered from cognitive decline at 3 months after their operation.


CONCLUSIONS
These data suggest that the incidence of cognitive dysfunction after CABG has previously been greatly overestimated.
Keizer
A M A
AM
Department of Psychiatry, University Medical Centre Utrecht, Utrecht, the Netherlands.
Hijman
R
R
Kalkman
C J
CJ
Kahn
R S
RS
van Dijk
D
D
D000368:Aged; D000465:Algorithms; D003072:Cognition Disorders / Q000453:epidemiology* / Q000209:etiology / Q000523:psychology*; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D047549:Coronary Artery Bypass, Off-Pump / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011183:Postoperative Complications / Q000453:epidemiology* / Q000523:psychology*; D009626:Terminology as Topic