In new study published in the November edition of Anesthesiology, researchers examine a concern common among Seniors and their caregivers - the occurrence of long-term cognitive decline following surgery or illness. Overall, researchers did not find long-term cognitive decline to be independently attributable to surgery or illness. In addition, surgery and illness were not associated with accelerated progression of dementia.

"The concerns surrounding postoperative cognitive decline (POCD) following surgery certainly will not evaporate following publication of this study," said Michael S. Avidan, M.B., B.Ch, F.C.A.S.A. "The important message to take from these findings is that persistent cognitive deterioration following surgery might not be a major public health problem. The decision to proceed with surgery should presently be made based on a person's general health, and the specific risks and benefits of the procedure."

There is a widely held belief by physicians and the public that elderly patients experience significant long-term deterioration in mental function following surgery. "The evidence for long-term cognitive deterioration following surgery is not clinically obvious, is based on studies using psychological testing for subtle changes in neurocognitve function, and is dependent on complex statistical methods and the selection of control subjects," said Alex S. Evers, M.D. "Our study took a new statistical approach to analyzing the impact of surgery on the trajectory of long term cognitive function, and failed to find evidence for post-operative cognitive deterioration"

Drs. Avidan and Evers and colleagues from Washington University School of Medicine examined long-term cognitive decline using an innovative investigative approach in cooperation with Washington University's Alzheimer Disease Research Center (ADRC), which allowed for the inclusion of participants with pre-existing cognitive impairment in the study.

"There has been a strong perception that people with pre-existing cognitive impairment may be more susceptible to persistent deterioration," said Dr. Avidan. "Previous studies have almost always excluded patients with pre-existing cognitive impairment, making it impossible to determine if such patients are more susceptible to POCD. The widely held perceptions about POCD may increase anxiety about surgery, and even impact the decision to proceed with surgery."

In this retrospective study, researchers identified three groups from participants tested annually at ADRC: those with non-cardiac surgery, illness or neither. Use of ADRC participants enabled researchers the opportunity for long-term tracking of patients' cognitive function before and after surgery and illness.

Researchers sought to test the hypothesis that there is measurable and lasting cognitive decline following non-cardiac surgery or major illness in older adults. Taking the analysis further, researchers also sought to determine if patients with pre-existing, mild cognitive impairment or early Alzheimer's disease are particularly vulnerable and experience significant cognitive decline following surgery or illness.

Of 575 participants from the ADRC database, 214 were categorized as nondemented and 361 had very mild or mild dementia at enrollment.

Tracking the longitudinal trajectories of cognitive decline in participants over time, it was revealed that cognitive decline did not differ among the three study groups (surgery, illness, control). Participants categorized as demented did decline more strikingly than participants categorized as nondemented. Of the nondemented participants 23% developed detectable impairment during the study period, progressing to a clinical dementia rating (CDR) greater than zero. Importantly, this decline was not more common following surgery or illness.

Looking to future questions on the occurrence and causes of cognitive decline, Dr. Evers noted that "it is important to realize that our study does not address post-operative delirium and early cognitive impairment, which can be clinically obvious problems."

Dr. Avidan concluded, "With mounting basic science studies implicating POCD as a real phenomenon, coupled with long-term outcome studies associating POCD with increased mortality, it is now imperative to conduct properly designed studies with meaningful clinical endpoints to determine whether any specific surgery, anesthetic technique or patient characteristic might be independently associated with long-term POCD."

For more information, visit the journal Anesthesiology Web site at http://www.anesthesiology.org.

Source
American Society of Anesthesiologists