New research may help identify older surgical patients who are more susceptible to delirium.
Delirium, or sudden severe confusion due to rapid changes in brain function that can occur with physical or mental illness, affects 15 percent to 53 percent of older surgical patients. It has been linked with longer hospital stays, greater postoperative complications and higher rates of discharge to nursing homes.
In the United States, health care costs attributable to delirium are about $164 billion annually, yet there are no established biological markers to guide the diagnosis or management of the condition, according to scientists.
To look for potential blood-based markers of delirium, researchers at Beth Israel Deaconess Medical Center (BIDMC) in Boston screened plasma from adults without dementia aged 70 and older undergoing major non-cardiac surgery using data from the Successful Aging after Elective Surgery Study.
Of the 566 patients, 24 percent experienced delirium. Plasma was collected at four time points: Preoperatively (PREOP), in the postanesthesia care unit (PACU), on postoperative day two (POD2) and at a one-month follow-up appointment (PO1MO).
“Our findings demonstrate that, in patients who go on to develop delirium, CRP levels in blood are slightly increased before surgery and further increase after surgery relative to patients who do not develop delirium,” said Towia Libermann, Ph.D., who is director of the Genomics, Proteomics, Bioinformatics and Systems Biology Center at BIDMC and associate professor of medicine at Harvard Medical School (HMS).
He noted that increased plasma CRP levels are linked to various clinical conditions, which means that CRP is not a highly specific marker for delirium.
To identify more selective delirium markers, the researchers are planning to expand their search to include metabolites, lipids and less abundant proteins in the blood.
“We anticipate that the most specific delirium biomarkers will be found at very low concentrations and not among the most common proteins,” Libermann explained.
Uncovering such markers may provide clues regarding the mechanisms that underlie the development of delirium, he noted.
Libermann suggested that common mechanisms may be shared by all patients developing postoperative delirium. More CRP may indicate a pre-inflammatory state before surgery, predisposing those patients to a greater inflammatory response in surgery and increased delirium risk, he said.
“From a clinical standpoint, our findings suggest that CRP could be used to risk-stratify patients before surgery, enabling proactive interventions that target patients at risk for developing postoperative delirium,” said Sarinnapha Vasunilashorn, Ph.D., co-lead author and postdoctoral fellow in the Division of General Medicine at Primary Care at BIDMC and HMS.
The study was published in the journal Biological Psychiatry.