Diagnostic Value of Cholinesterase Activity for the Development of Postoperative Delirium after Cardiac Surgery

Diagnostic Value of Cholinesterase Activity for Postoperative Delirium

Nowadays, multivariable analyses are a mainstay in the development of risk models. We appreciate the attention to detail demonstrated by the discussants and would hereby like to clear the ambiguities regarding the statistical tests used in our study “Diagnostic Value of Cholinesterase Activity for the Development of Postoperative Delirium after Cardiac Surgery”.[1] In this study, we screened 207 patients based on the inclusion and exclusion criteria mentioned.[1] Following this, we performed a univariable analysis (Tables 1 and 2). Based on these results, we built a risk model based on binary logistic regression. The parameters we incorporated in the multiple variable analysis were the preoperative Mini–Mental State Examination score, a drop in postoperative cholinesterase (CHE) activity (preoperative CHE compared with CHE on postoperative day (POD 0) of more than 50%, and an early postoperative CHE activity (POD 0) below 4,800 U/L. We omitted the steps showing the suitability of the regression model, to be concise and keep the focus on the clinical study at hand. The regression model was verified using the various regression diagnostics as presented by Hickey et al,[2] which include goodness of fit test as well as tests for autocorrelation, multicollinearity, and heteroscedasticity.

Butyrylcholinesterase has been reported to behave as a negative acute phase protein under various circumstances, which by definition is associated with a decrease of at least 25%.[3] [4] For the purpose of this study, we chose the 50% cutoff to compensate for the postoperative stress following surgery. As the authors have correctly stated, this study only confirms the associations of postoperative CHE activity of more than 50% and an early postoperative CHE activity below 4,800 U/L with the development of postoperative delirium.

The goal of this study was to support that routine estimation of CHE activity may serve as an additional diagnostic tool allowing for early diagnosis and treatment of postoperative delirium in patients after cardiac surgery. Performing a receiver operating characteristic curve analysis in an already screened population would open up the analysis to a bias, as postoperative delirium is a multifactorial clinical entity. Our data support the neuroinflammatory etiology of postoperative delirium in complex postcardiac surgical patients as one of the contributing factors.

Publication History

Article published online:
25 August 2021

• References

• 1 Saha S, Karaca K, Jebran AF. et al. Diagnostic value of cholinesterase activity for the development of postoperative delirium after cardiac surgery. Thorac Cardiovasc Surg 2020; ••• DOI: 10.1055/s-0040-1716897.
• 2 Hickey GL, Kontopantelis E, Takkenberg JJM, Beyersdorf F. Statistical primer: checking model assumptions with regression diagnostics. Interact Cardiovasc Thorac Surg 2019; 28 (01) 1-8
• 3 Santarpia L, Grandone I, Contaldo F, Pasanisi F. Butyrylcholinesterase as a prognostic marker: a review of the literature. J Cachexia Sarcopenia Muscle 2013; 4 (01) 31-39
• 4 Fikry Y, Elsayed A, Sayed M, Nabil D. Can plasma cholinesterase act as an adjuvant prognostic index in acute burn cases?. Ain Shams J Forensic Med Clin Toxicol 2021; 36: 49-60