High preoperative plasma neopterin predicts delirium after cardiac surgery in older adults

To examine the association between plasma levels of pterins and amino acids and postoperative delirium.

Prospective cohort study.

Cardiothoracic service in an university hospital in Rotterdam, the Netherlands.

One hundred twenty-five individuals aged 70 and older undergoing elective cardiac surgery.

Plasma pterins and amino acids were measured pre- and postoperatively. Using multiple logistic regression analyses, the associations between pterins and amino acid levels and postoperative delirium were examined in relation to age, sex, comorbidity, cognitive functioning (Mini-Mental State Examination (MMSE) score), and cardiac risk factors.

Delirium incidence in the main study group was 31.3%. The preoperative measures associated with delirium were neopterin (odds ratio (OR) = 1.05, P = .009); MMSE score less than 28 (OR = 4.39, P = .001); European System for Cardiac Operative Risk Evaluation score greater than 6 (OR = 2.84, P = .03); and combined coronary artery bypass graft (CABG) and aortic, mitral, or tricuspid valve surgery (OR = 4.32, P = .01). Postoperative measures associated with delirium were neopterin (OR = 3.84, P = .02), homovanillic acid (HVA, OR = 1.01, P = .04), and preoperative MMSE score less than 28 (OR = 3.32, P = .008).

Preoperatively high neopterin levels predicted delirium after cardiac surgery in older adults, in addition to the well-known risk factors of poor cognitive function, high cardio-surgical risk, and combined CABG and valve surgery. Postoperative neopterin and HVA levels were also found to be associated with delirium, together with preoperative cognitive functioning. Plasma neopterin may be a candidate biomarker for delirium after cardiac surgery in these older adults.