Detailed insight into the impact of postoperative neuropsychiatric complications on mortality in a cohort of cardiac surgery subjects: a 23,000-patient-year analysis

Abstract

Objectives: This study sought to evaluate the impact of postoperative delirium with/without cerebral ischemia on short- and long-term mortality in a large cohort of cardiac surgery patients.

Design: The study constituted a prospective cohort observation of patients following various cardiac surgery procedures.

Setting: The investigation was conducted in a single high-volume tertiary cardiac surgery center.

Participants: Consecutive candidates for cardiac surgery (n = 8,792) from 2003 to 2008 were subjected to the following exclusion criteria: History of any psychiatric disorders, alcohol abuse and intake of psychoactive drugs and incomplete data.

Interventions: No additional interventions were performed, except for standard perioperative management.

Measurements and main results: 5,781 patients finally were assigned to cohorts depending on the presence of postoperative delirium with/without cerebral ischemia and then prospectively followed up over the median time of 46 months. Overall 30-day mortality in patients with delirium was 15.25%, including 6.43% of patients without and 38.46% of subjects with cerebral ischemia. After adjustment for more than 100 perioperative variables, short-term mortality was associated independently with delirium (OR = 3.735), stroke (OR = 5.698), hypertension (OR = 0.333), urgency of surgery (OR = 13.018), baseline plasma glucose and protein concentrations and blood transfusions (AUROC for the model 0.94). Long-term mortality in patients who developed delirium was 23.31%, including 15.2% of patients without and 44.62% of those with postoperative stroke. Long-term mortality independently corresponded with stroke (HR = 3.968), urgent surgery (HR = 27.643), baseline plasma glucose and protein concentrations, chronic obstructive pulmonary disease and blood transfusions. Impact of postoperative delirium was insignificant (p = 0.2). Compared to subjects with cerebral ischemia, death in patients only with delirium was less frequently of cardiovascular cause (p < 0.01).

Conclusions: Delirium with/without cerebral ischemia significantly worsened the short-term prognosis. Stroke, yet not delirium, considerably increased the long-term mortality, especially of cardiovascular origin.

Keywords: cardiac surgery; delirium; determinants; mortality; postoperative complication; survival analysis.