The presence of high levels of C-reactive protein may act as a marker to help identify older patients who would benefit from preventive measures against delirium before undergoing surgery.
Researchers from the Beth Israel Deaconess Medical Center in Boston noted that delirium affected 15-53% of older surgical patients and was linked with longer hospital stays and more complications.
“CRP could be used to risk stratify patients before surgery”
They said their research provided insights into the potential mechanisms involved in the development of delirium and may help clinicians assess risk so preventive measures could be taken.
To look for potential blood-based markers of delirium, researchers screened plasma from adults without dementia aged 70 and older undergoing major non-cardiac surgery.
Of the 566 patients enrolled, 24% experienced delirium. Plasma was collected at four time points – pre-operatively, in the post-anaesthesia care unit, on postoperative day two and at a one-month follow-up appointment.
High levels of a protein called C-reactive protein, which has been linked to inflammation and infection, emerged from an analysis of more than 100 proteins as being strongly linked to delirium.
Compared with patients without delirium, those with delirium had significantly higher plasma CRP levels at three of the four time points, with the exception of the follow-up appointment.
Although the relationship between CRP and delirium has been previously reported, the new US study is the first to document and analyse CRP levels before onset of symptoms, said its authors in the journal Biological Psychiatry.
Lead study author Dr Towia Libermann said: “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.”
He noted that increased plasma CRP levels were linked to various clinical conditions, meaning CRP was not a highly specific marker for delirium.
To identify more selective delirium markers, the researchers were 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,” he said.
Co-author Sarinnapha Vasunilashorn added: “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.”