Re: Incidence and risk factors of postoperative delirium in elderly patients undergoing urological surgery: A multi‐institutional prospective study

Abstract

In a multi-institutional prospective study, Matsuki et al. assessed incidence and risk factors of postoperative delirium (POD) in elderly patients undergoing urological surgery, and showed that a history of cerebrovascular disease, low Hasegawa Dementia Scale-Revised score and serum albumin level, and long surgery duration were independent risk factors for POD. 1 As POD has been significantly associated with increased length of hospital stay, costs, morbidity and mortality in patients undergoing urological surgery, their findings have potential clinical implications. However, we noted several issues in this study that were not well addressed.First, in this study, the POD that occurred within 7 days after surgery was defined by a criterion of Intensive Care Delirium Screening Checklist ≥3 points in accordance with the Japanese version of the Intensive Care Delirium Screening Checklist. In the new recommendations for the nomenclature of cognitive change associated with anesthesia and surgery-2018, however, it is required that definitions of POD must meet the diagnostic criteria of delirium in the Diagnostic and Statistical Manual of Mental Disorders fifth edition. 2 Evidently, the use of Intensive Care Delirium Screening Checklist ≥3 points for definitions of POD in this study could not achieve the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders fifth edition for delirium. Actually, the intensive care unit delirium assessment tools are not adequately sensitive to identify POD in non-intensive care unit settings. We are concerned that the use of an improper criterion of definition in this study would have confounded diagnosis of POD.Second, by using a cut-off value of <3.5 g/dL (diagnostic criteria of hypoalbuminemia), a low serum albumin level was identified as an independent risk factor for POD. We noted that mean hemoglobin levels were 12.7 AE 1.8 and 13.2 AE 1.8 g/dL in patient with and without POD, with no significant difference. However, only comparing mean hemoglobin levels might have limited clinical values. The authors should report the incidence of preoperative anemia and assess the effect of preoperative anemia on the occurrence of POD. It must be emphasized that preoperative anemia is common among elderly surgical patients, and has been significantly associated with an increased risk of POD. In clinical practice, correction of both hypoalbuminemia and anemia before surgery has become one element of multicomponent prehabilitation programs reducing the occurrence of POD in elderly patients undergoing major surgery. 3 Third, only providing the type of anesthesia (general or spinal) was not enough when anesthetic interventions were taken as confounders for identifying potential risk factors of POD by multivariate analysis. Among drugs commonly used in anesthetic practice, opioids, sevoflurane, benzodiazepines and anticholinergics have been implicated in the development of POD. Other than great blood loss and transfusion provided in this study, furthermore, intraoperative hemo...