Mixed method study of the incidence, peri-operative risk factors and patient experiences of post-operative delirium and associated post-traumatic stress syndrome following cardiac surgery

Abstract

INTRODUCTION: Delirium, an acute fluctuation of cognitive function, is a common complication after cardiac surgery. There are multiple pre, post and intra-operative factors attributed to the development of delirium. Whatever the precipitating factors, delirium not only causes psychological distress to the patient but also their family members. In some cases, this psychological upset continues to affect the patient after discharge from hospital, referred to as post-traumatic stress syndrome (PTSS). Despite this, there is little known about the aftermath of delirium and the associated patient experience, especially following cardiac surgery.

AIM: The aim of the study was to identify the incidence, peri-operative risk factors and explore patient experiences of post-operative delirium and associated post-traumatic stress syndrome following cardiac surgery.

METHODS: In order to address the aim, the study adopted a mixed methods approach. Data collection took place in a large teaching hospital in Scotland. -Phase I: Quantitative phase (Pre Admission Clinic/ Ward assessment for in-patients) Data collection included identifying peri-operative risk factors, assessment of personality and mood using validated tools, and screening for delirium. -Phase II-a: Quantitative phase (6-8 weeks following discharge) Following phase I, 'Purposive Criterion' sampling was used with the criterion being the phenomenon of delirium to enroll patients into phase IIa of the study. Data collection included validated tools for re-assessing mood, re-screening for delirium and PTSS diagnoses using SCID - Structural Clinical Interview for DSM (Diagnostic and Statistical Manual for Psychiatric Disorders). -Phase II-b: Qualitative phase (Telephone follow up at three months) Sixteen participants from phase IIa were selected and enrolled in phase IIb. Data collection included two validated tools - SCID and delirium screening and an additional semi-structured interview to gain an understanding of the patient experience.

FINDINGS: The study recruited 406 participants (72% male, mean age 67 years, SD=10.50). The EuroSCORE (European System for Cardiac Operative Risk Evaluation) which provides a simple, additive risk model in European adult cardiac surgery patients, was calculated to be 4.77 (SD=2.62). This suggests a moderate level predicted risk of 30-day mortality across the study population following cardiac surgery. The incidence of post-operative delirium was 18.3%.

Univariate analysis of the data showed that ‘Age’ (p Qualitative analysis included examining the transcribed interviews using a 'thematic approach'. This uncovered five main themes: These were 'what I remember or not' (failure to recall details during period of delirium); 'Not right in my head' (recall information juxtaposed with relative's accounts); 'My body' (focus on physical recovery after surgery); 'No regrets' (decision to undergo surgery despite complications); 'Reassurance' (relief and comfort gained with follow up).

CONCLUSION: In summary, from the quantitative data, age at time of surgery was the only attributable risk factor for post-operative delirium. The qualitative data informs the after-effects of in–hospital delirium and clearly distinguishes between post-delirium anxiety states and PTSS.

Recommendations for appropriate patient selection should focus on biological age and frailty along with pre-operative optimisation. Clinicians should explain about delirium as a serious complication prior to obtaining consent for cardiac surgery. Also, ensure that patients and families are more prepared and have a better understanding when psychological issues emerge after elective cardiac surgery.