Effect of motor subtypes of delirium in the intensive care unit on fast-track failure after cardiac surgery

Abstract

ObjectiveThe purpose of the study was to evaluate the association between motor subtypes of postoperative delirium in the intensive care unit and fast-track failure (a composite outcome of prolonged stay in the intensive care unit >48 hours, intensive care unit readmission, and 30-day mortality) after cardiac surgery. MethodsThis was a secondary analysis of a prospective cohort study of 600 consecutive adults undergoing cardiac surgery at a university hospital in Hong Kong (July 2013 to July 2015). The motor subtypes of delirium were classified using the Richmond Agitation Sedation Score and Confusion Assessment Method intensive care unit assessments performed by trained bedside nurses. A generalized estimating equation was used to estimate a common relative risk of fast-track failure associated with motor subtypes. ResultsThe incidences of hypoactive, hyperactive, and mixed motor subtypes were 4.3% (n = 26), 4.0% (n = 24), and 5.5% (n = 33), respectively. Fast-track failure occurred in 88 patients (14.7%). There was an association between delirium (all subtypes) and fast-track failure (P = .048); hyperactive delirium (relative risk, 1.95; 95% confidence interval, 0.96-3.94); hypoactive delirium (relative risk, 2.79; 95% confidence interval, 1.34-5.84); and mixed delirium (relative risk, 2.55; 95% confidence interval, 1.11-5.88). Hypoactive and mixed subtypes were associated with prolonged intensive care unit stay (both P = .001). ConclusionsPatients with pure hypoactive delirium had a similar risk of developing fast-track failure as other motor subtypes. Differentiation of motor subtypes is unlikely to be clinically important for prognostication of fast-track failure. However, because delirium is associated with poor outcomes, potential treatment strategies should address all subtypes equally.