Delirium after cardiac surgery incidence and perioperative risk factors in a prospective cohort

Delirium is an aetiologically nonspecific cerebral syndrome characterised by disturbances in consciousness, attention, perception, cognition, memory, psychomotor activity, emotion, and the sleep–wake cycle. It frequently occurs after cardiac surgery, with multiple perioperative factors contributing to its onset, and is linked to adverse patient outcomes. This study aimed to determine the incidence and perioperative risk factors for postoperative delirium. This prospective study was conducted in two phases across the peri-operative pathway of patients undergoing cardiac surgery. Phase I involved data collection either at the pre admission clinic for elective patients or on in patient wards for urgent referrals. During this phase, relevant pre-disposing and precipitating risk factors for delirium were documented. Baseline assessments for risk factors were collected as well as the following: Personality evaluation: The Ten Item Personality Inventory (TIPI); Mood assessment: The Hospital Anxiety and Depression Scale (HADS); Delirium screening: The 4 ‘A’s Test (4AT). Phase II took place three months post surgery and included only those participants who had experienced post operative delirium during their in-patient stay. These participants were invited to attend a review clinic for follow-up assessments comprising of the following: Re-screening for delirium; Repeat HADS evaluation; Post traumatic stress symptoms (PTSS) assessment using the Structured Clinical Interview for DSM Disorders (SCID). Over 12 months, 816 patients were screened and 406 recruited (mean age 67 ± 10.5 years; 72% male). Postoperative delirium occurred in 18.3% of patients. Age (p < 0.001) and pre-operative renal impairment (p = 0.008) were associated with delirium in initial analyses; however, the association with renal impairment was not significant after adjustment for age (OR 1.89, 95% CI 0.88–4.05). At three month follow-up, post traumatic stress symptoms were identified in only two patients. Post operative delirium affected nearly one in five cardiac surgery patients, with advanced age emerging as the only variable retaining independent significance. These findings highlight the need for targeted, age focused risk assessment and prevention strategies to improve outcomes in this high risk population.