Subsyndromal Delirium in Cardiac Surgery Patients Risk Factors and Outcomes of the Different Trajectories

Background Subsyndromal delirium (SSD), a subthreshold form of delirium, is related to longer length of stay and increased mortality rates among older adults. Risk factors and outcomes of SSD in cardiac surgery patients are not fully understood. Objective The aim of this study was to assess and describe the characteristics and outcomes related to trajectories of SSD and delirium in cardiac surgery patients. Methods In this secondary analysis of a retrospective case-control (1:1) cohort study, SSD was defined as a score between 1 and 3 on the Intensive Care Delirium Screening Checklist paired with an absence of diagnosis of delirium on the day of assessment. Potential risk factors (eg, age) and outcomes (eg, mortality) were identified from existing literature. Patients were grouped into 4 trajectories: (1) without SSD or delirium, (2) SSD only, (3) both, and (4) delirium only. These trajectories were contrasted using analysis of variance or chi(2) test. Results Among the cohort of 346 patients, 110 patients did not present with SSD or delirium, 62 presented with only SSD, 69 presented with both, and 105 presented with only delirium. In comparison with patients without SSD or delirium, patients with SSD presented preoperative risk factors known for delirium (ie, older age, higher European System for Cardiac Operative Risk Evaluation II) but underwent less complicated surgical procedures, received fewer transfusions postoperatively, and had a lower positive fluid balance postoperatively than patients who presented with delirium. Patients with both SSD and delirium had worse outcomes in comparison with those with delirium only. Conclusion This study stresses the importance for healthcare professionals to identify SSD and prevent its progression to delirium.