The effect of delirium preventive measures on the occurrence of postoperative cognitive dysfunction in older adults undergoing cardiovascular surgery. The DelPOCD randomised controlled trial

Study objective: This trial examines the effect of delirium preventive measures on the incidence of postoperative cognitive dysfunction in older adults. Design: In a randomised approach, a delirium prevention and a standard care group were compared regarding manifestation of postoperative cognitive dysfunction at seven days, three and twelve months postoperatively (primary outcome). To correct for practice effects and age-depended cognitive decline, a control group of age matched healthy subjects was included. Setting: The trial was conducted at the University Medical Centre Hamburg between 2014 and 2018, data assessment took place in the Anaesthesia Outpatient Clinic and on the surgical ward. Patients: A total of 609 patients >= 60 years scheduled for cardiovascular surgery were enrolled, allocated treatment was received by 284 patients in the delirium prevention and 274 patients in the standard care group. Intervention: The intervention consisted of a delirium prevention bundle including reorientation measures, sleeping aids and early mobilisation. Measurements: Cognitive functions were assessed via neuropsychological testing of attention, executive functions including word fluency, and verbal memory utilizing a computerised test of attentional performance, the trail making test, the digit span subtest from the Wechsler Adult Intelligence Scale-IV, the verbal learning and memory test, and the Regensburg Word Fluency Test. Assessments were performed preoperatively and at three time points postoperatively (one week, three months and 12 months). Main results: Postoperative cognitive dysfunction was defined as a clinically meaningful decline in at least two out of nine chosen test parameters compared to the preoperative level (reliable change index <= -1.96). The rates of postoperative cognitive dysfunction were 25.9% (delirium prevention group, n = 284) vs. 28.1% (standard care group, n = 274) (X-2(1,n = 433) = 0.245;p = 0.621] at postoperative day seven and declined to 7.8% vs. 6.8% (X-2(1,n = 219) = 0.081;p = 0.775] and 1.3% vs. 5.6% (p = 0.215, Fisher's exact test) at three and 12 months following surgery, respectively. The postoperative delirium rates did not differ between the two groups (delirium prevention group: 13.4% vs. standard care group: 17.3%). Attentional performance was impaired shortly after surgery, whereas verbal delayed recall was most frequently affected over the whole postoperative period. Conclusion: These findings suggest that an intervention combining specific measures extracted from established postoperative delirium prevention programs did not reduce the rate of postoperative cognitive dysfunction in older adults.