Preoperative cerebrospinal fluid and plasma markers of inflammation and neurodegeneration predict mortality eight years later in an observational cohort study of postoperative delirium in an older elective arthroplasty population

Background
Between 2012-2014, an observational cohort study of postoperative delirium (POD) in an elective arthroplasty population recruited 315 individuals aged over 65, without a diagnosis of dementia. We are now conducting a follow-up study to determine what effect POD has on cognition years later.

Method
In the baseline study, neuropsychological testing was undertaken preoperatively, cerebrospinal fluid (CSF) was sampled at the time of spinal anaesthesia and delirium was assessed daily on days 1-3 postoperatively. Stored CSF (n = 270) was analysed for markers of inflammation and neurodegeneration. In 2020, all surviving participants were invited to take part in the follow-up study.

Result
The average age of the cohort at baseline was 74.4 (5.8) years. Eight years later, 84% (n=264) of the observational study participants are still alive. Mortality rates in the intervening years are higher in those who developed POD (14/44, 32%) than those who did not (37/271, 14%), but is not statistically significant (p=0.13). Significant predictors of mortality in all participants included multi-morbidity (p=0.007), age at surgery (p
Conclusion
The majority of participants in this elective arthroplasty observational cohort are still alive eight years later. Older age at time of surgery, multimorbidity, lower neuropsychological performance and increased preoperative CSF measures of inflammation and neurodegeneration were associated with mortality in adults eight years following elective orthopaedic surgery.