Dr Hina Habib, Dr Samra Hassan, Dr Hafiz Muhammad Umair.
Introduction: Previous reports have provided incoherent evidence on whether postoperative delirium (POD) is a risk factor for POCD. We have thus analysed the relationship between POD and cognitive change after heart surgery and we have assessed how POD is related to preoperative cognitive domain values. Methods: The Confusion Assessment Method (CAM) for the Intensive Care Unit and traditional CAM, along with the chart analysis, were evaluated in postoperative delirium. Before elective heart surgery and 1 month or 1 year after, the cognitive function was tested with a neuropsychological test battery. The Reliable Change Index (RCI) was used to calculate cognitive change. To correct for uncertainty, multiple linear regression was used. Results: 23 (12.5 per cent) of the 184 patients who completed the baseline assessment developed PODs. At 1 month, the decrease in cognitive performance was worse in POD [median composite RCI1.00, interquartile range (IQR) 1.67 to 0.28] patients than in POD-free patients (RCI0.04, IQR0.70 to 0.63, P1⁄40.02). At 1yr, both groups showed average cognitive improvement compared to baseline (POD median RCI 0.25, IQR 0.42 to 1.31, compared to non-POD patients RCI 0.92, IQR 0.18–1.53; P1⁄40.08). The correction of differences in age and level of education did not change the results. Patients with POD performed less well on the preoperative Trail making test part A (P1⁄40.03) than patients without POD. Conclusion: Postoperative delirium is independently associated with cognitive impairment 1 month after surgery but typically improves cognitive function within 1yr. Patients with POD predisposition may be identified by worse performance in the attention task prior to surgery.