The association between diabetes mellitus and postoperative cognitive dysfunction: a systematic review and meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a typical consequence following surgery, particularly in cardiac surgeries. Despite its high incidence, the underlying etiology remains unclear. While diabetes mellitus (DM) has been associated with cognitive impairment, its specific function in POCD development remains unidentified. This study aims to evaluate the connection between DM and the risk of POCD.

METHODS

We conducted a comprehensive search of PubMed, Embase, Web of Science, and the Cochrane Library databases for studies of DM and risk with POCD, collecting data up to 14 September 2023. We assessed publication bias, heterogeneity, and study quality, adhering to PRISMA and AMSTAR guidelines.

RESULTS

Our study comprised 38 trials involving 8748 individuals, with 7734 patients undergoing follow-up. The pooled results showed that individuals with DM had an increased incidence of POCD compared to nondiabetic individuals (RR: 1.44, 95% CI: 1.26-1.65). The incidence of POCD was significantly higher in the group of patients with an average age older than 65 years (RR: 1.69, 95% CI: 1.30-2.20) compared with diabetic patients with an average age younger than 65 years (RR: 1.29, 95% CI: 1.09-1.64). Compared with diabetic patients undergoing cardiac surgery (RR: 1.33, 95% CI: 1.15-1.53), patients receiving non-cardiac surgery showed a greater incidence of POCD (RR: 2.01, 95% CI: 1.43-2.84).

CONCLUSION

Current evidence underscores that diabetic patients face a significantly higher risk of POCD compared to their nondiabetic counterparts. Further research is warranted to clarify the precise mechanisms of this relationship and explore potential preventive strategies for diabetic patients.

Postoperative cognitive dysfunction: a concept analysis

BACKGROUND

Post-operative cognitive dysfunction (POCD) is a concern for clinicians that often presents post-surgery where generalized anesthesia has been used. Its prevalence ranges from 36.6% in young adults to 42.4% in older individuals. Conceptual clarity for POCD is lacking in the currently body literature. Our two-fold purpose of this concept analysis was to (1) critically appraise the various definitions, while also providing the best definition, of POCD and (2) narratively synthesize the attributes, surrogate or related terms, antecedents (risk factors), and consequences of the concept.

METHOD

The reporting of our review was guided by the PRISMA statement and the 6-step evolutionary approach to concept analysis developed by Rodgers. Three databases, including Medline, CINAHL, and Web of Science, were searched to retrieve relevant literature on the concept of POCD. Two independent reviewers conducted abstract and full-text screening, data extraction, and appraisal. The review process yielded a final set of 86 eligible articles.

RESULT

POCD was defined with varying severities ranging from subtle-to-extensive cognitive changes (1) affecting single or multiple cognitive domains that manifest following major surgery (2), is transient and reversible, and (3) may last for several weeks to years. The consequences of POCD may include impaired quality of life, resulting from withdrawal from the labor force, increased patients' dependencies, cognitive decline, an elevated risk of dementia, rising healthcare costs, and eventual mortality.

CONCLUSION

This review resulted in a refined definition and comprehensive analysis of POCD that can be useful to both researchers and clinicians. Future research is needed to refine the operational definitions of POCD so that they better represent the defining attributes of the concept.

The risk factors of postoperative cognitive dysfunction in patients undergoing carotid endarterectomy: an updated meta-analysis

OBJECTIVE

The purpose of the current meta-analysis was to determine the incidence and risk factors to provide a scientific basis for prevention and treatment of postoperative cognitive dysfunction (POCD) after carotid endarterectomy (CEA).

METHODS

Relevant articles published before October 2022 were searched from Pubmed/MEDLINE, Cochrane and Embase databases. The outcomes were the incidence and risk factors for POCD. A random-effects model was applied to estimate the overall odds ratios (ORs) and mean differences (MDs) for all risk factors through STATA 14.0 and RevMan 5.4. The quality of eligible studies was evaluated by Newcastle-Ottawa Scale (NOS) as previously described.

RESULTS

A total of 22 articles involving 3459 CEA patients were finally identified. The weighted mean incidence of POCD was 19% (95% confidence intervals (95% CI) 0.16-0.24, P < 0.001). Of the 16 identified risk factors, hyperperfusion (OR: 0.54, 95% CI 0.41-0.71) and degree of internal carotid artery (ICA) stenosis (OR: 5.06, 95% CI 0.86-9.27) were the potential risk factors of POCD, whereas patients taking statins preoperative had a lower risk of POCD (OR: 0.54, 95% CI 0.41-0.71). Subgroup analysis revealed that the risk of POCD at 1 month after CEA was higher in patients with diabetes (OR: 1.70, 95% CI 1.07-2.71).

CONCLUSION

The risk factors of POCD were hyperperfusion and degree of ICA stenosis, while diabetes could significantly increase the incidence of POCD at 1 month after surgery. Additionally, preoperative statin use could be a protective factor for POCD following CEA.

Obesity and Postoperative Cognitive Dysfunction: A Curious Association

Postoperative cognitive dysfunction (POCD) is a medical condition that impacts cognitive function after surgery, particularly major procedures. Patients with POCD may experience physical symptoms, such as depression, anxiety, and fatigue, severely undermining their quality of life. Research establishes the connection between obesity and cognitive dysfunction since patients diagnosed with obesity are more susceptible to cognitive decline. Although obesity poses a significant risk factor for cognitive impairment, the link between obesity and POCD is still inadequately understood. Therefore, this systematic review explores the correlation between obesity and POCD by detailing potential mechanisms underlying this relationship and identifying areas for further research. Following the guidelines for systematic reviews, we conducted a literature search between August 2022 and April 2023, which identified studies with a substantial number of patients with POCD after major surgeries, including coronary artery bypass grafting, gastrointestinal procedures, cholecystectomy, and carotid endarterectomy. Our findings also demonstrated that a significant percentage of these had obesity, which was statistically significant as a risk factor for cognitive decline. Pathological processes, such as changes in vascular endothelium integrity, systemic inflammation induced by obesity, and apolipoprotein E-epsilon-4 expression, have been identified to contribute to POCD after surgery. Despite the promising results, there remains a gap in the literature. Thus, it is crucial to investigate the relationship between obesity and POCD further, uncover more potential underlying pathophysiological processes, and identify therapeutic targets. These measures would enable healthcare practitioners to prevent or reduce cognitive dysfunction associated with obesity in surgical patients.

Cognitive Dysfunction and Mortality After Carotid Endarterectomy

Background: Carotid endarterectomy (CEA) has been associated with both postoperative cognitive dysfunction (POCD) and improvement (POCI). However, the prognostic significance of postoperative cognitive changes related to CEA is largely unknown. The aim of this study was to examine the associations between postoperative cognitive changes after CEA and long-term survival.

Methods: We studied 43 patients 1 day before CEA as well as 4 days and 3 months after surgery with an extensive neuropsychological test array, and followed them for up to 14 years. POCD and POCI relative to baseline were determined with the reliable change index derived from 17 healthy controls. Associations between POCD/POCI and mortality within the patient group were studied with Cox regression analyses adjusted for confounders.

Results: POCD in any functional domain was evident in 28% of patients 4 days after surgery and in 33% of patients 3 months after surgery. POCI was shown in 23% of patients at 4 days and in 44% of patients at 3 months. POCD at 3 months was associated with higher long-term mortality (hazard ratio 5.0, 95% CI 1.8–13.9, p = 0.002) compared with patients with no cognitive decline.

Conclusions: Our findings suggest that POCD in a stable phase, 3 months after CEA predicts premature death. Evaluation of postoperative cognitive changes is essential, and POCD in a stable phase after CEA should prompt scrutiny of underlying factors and better adherence to therapies to prevent recurrences and to promote early intervention in imminent deterioration.

Decrease of Coronal Optic Nerve Sheath Diameter is Associated With Postoperative Cognitive Decline in Patients Undergoing Carotid Endarterectomy

OBJECTIVE

Patients undergoing carotid endarterectomy (CEA) have a significant possibility of developing postoperative cognitive decline (POCD). POCD after surgery could be result from cerebral hypotension induced by cross-clamping or postoperative hyperperfusion. Optic nerve sheath diameter (ONSD) exhibits an excellent correlation with invasive intracranial pressure monitoring, Here, the authors explored the risk factors of POCD in patients undergoing CEA, paying close attention to ONSD to test the hypothesis that decrease of coronal ONSD was related to the incidence of POCD.

DESIGN

Observational retrospective review.

SETTING

Single tertiary academic center.

PARTICIPANTS

One hundred sixteen patients undergoing CEA from January 1, 2019 to December 31, 2019.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

A multivariate logistic regression, scatter diagrams, and a receiver operating curve were used to evaluate the ability to predict POCD though the change in coronal ONSD. This study ultimately enrolled 84 patients and the incidence of POCD within postoperative two days was 28.6%. Decrease of coronal ONSD (odds ratio [OR], 0.438; 95% confidence interval [CI] 0.217-0.881; p = 0.021) and total intravenous anesthesia (TIVA) (OR, 25.541, 95% CI 2.100-310.614, p = 0.011) were independent risk factors for POCD. Changes in coronal ONSD had an area under the curve to distinguish POCD of 0.716 (95% CI 0.531-0.902). Using a cutoff of 0.05 cm, changes of coronal ONSD had a sensitivity of 66.7% and specificity of 66.7%.

CONCLUSIONS

Decrease of coronal ONSD, measured by ultrasonography and TIVA, were associated with POCD. Change in coronal ONSD was a moderate predictor of incidence of POCD.

Statin loading in cardiovascular surgery: never too early to treat

PURPOSE OF REVIEW

The effects of statin loading before, during or after vascular interventions on cardiovascular and renal outcomes are discussed. Furthermore, the selection of optimal statin type and dose, according to current evidence or guidelines, is considered. The importance of treating statin intolerance and avoiding statin discontinuation is also discussed.

RECENT FINDINGS

Statin loading has been shown to beneficially affect cardiovascular outcomes, total mortality and/or contrast-induced acute kidney injury, in patients undergoing vascular procedures such as percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG), carotid endarterectomy (CEA), carotid artery stenting, endovascular aneurysm repair, open abdominal aortic aneurysms (AAA) repair and lower extremities vascular interventions. High-dose statin pretreatment is recommended for PCI and CABG according to current guidelines. Statin discontinuation should be avoided during acute cardiovascular events and vascular interventions; adequate measures should be implemented to overcome statin intolerance.

SUMMARY

Statin loading is an important clinical issue in patients with cardiac and noncardiac vascular diseases, including carotid artery disease, peripheral artery disease and AAA, undergoing vascular interventions. Cardiologists and vascular surgeons should be aware of current evidence and implement guidelines in relation to statin loading, discontinuation and intolerance.

Lipids: a personal view of the past decade

The past decade has witnessed considerable progress in the field of lipids. New drugs have been "rapidly" developed and some of these drugs have already been evaluated in event-based large trials. This evidence has led to the guidelines recommending new, more aggressive treatment goals for low-density lipoprotein cholesterol (LDL-C) levels. Although LDL-C remains the principal goal for cardiovascular disease (CVD) risk reduction, there has also been considerable interest in other lipid variables, such as high-density lipoprotein cholesterol, triglycerides, and lipoprotein(a). Statin intolerance is now considered a very important topic in daily clinical practice. This has resulted in more attention focusing on non-statin drugs [e.g., ezetimibe and proprotein convertase subtilisin/kexin 9 (PCSK9) inhibitors] and statin-related side effects. The latter mainly involve muscles, but there is also a need to consider other adverse effects associated with statin use (e.g., new onset diabetes). New specific areas of statin use have attracted interest. For example, statin-loading before procedures (e.g., coronary stenting), the prevention of stroke, and the treatment of non-alcoholic fatty liver disease (NAFLD). Statins will remain the most widely used drugs to treat dyslipidaemia and decrease CVD risk. However, we also need to briefly consider some other lipid-lowering drugs, including those that may become available in the future.

Easily Screenable Characteristics Associated with Cognitive Improvement and Dysfunction After Carotid Endarterectomy

BACKGROUND

Carotid endarterectomy (CEA) is an effective treatment for the prevention of stroke in patients with carotid artery stenosis. We aimed to clarify the incidence and risk factors for early cognitive dysfunction (eCD) and early cognitive improvement (eCI), defined as change in cognitive performance ≤24 hours after surgery, using a battery of neuropsychometric tests.

METHODS

In total, 585 patients undergoing CEA were tested with neuropsychometric tests before and after surgery; 155 patients undergoing "simple" spine surgery were the reference group. Patient performance for each test was evaluated by z scores. Cognitive change was defined as eCD (or eCI) if: 1) patients had a z score ≤-2 (or ≥2) in ≥2 cognitive domains or 2) patients had mean z scores across all domains ≤-1.5 (or ≥1.5). Associations between the categorical cognitive outcomes and variables of interest were modeled using the proportional odds model.

RESULTS

Of the 585 subjects, 24% had eCD, 6% had eCI, and 70% had "no change." Patients who had eCD were more likely to be statin naïve (odds ratio [OR] 1.23 [1.03-1.48], P = 0.02) or women (OR 1.27 [1.06-1.53], P = 0.02). Those with eCI were less likely to have less formal education (OR 0.95 [0.90-1.00], P = 0.04) and less likely to have diabetes mellitus (OR 0.8 [0.65-0.99], P = 0.04).

CONCLUSIONS

Patients having CEA may develop eCD or eCI postoperatively. Medications likely to be associated with less eCD are statins and aspirin, which correlate most strongly in asymptomatic patients. In addition to confirming previous findings, we found that women were more likely than men to develop eCD. More sex-specific studies and analysis are needed to better explore these findings.

Systematic review and meta-analysis of perioperative and long-term outcomes in patients receiving statin therapy before carotid endarterectomy

BACKGROUND

Carotid endarterectomy (CEA) is associated with perioperative stroke and mortality in a minority of cases. The aim of this systematic review and meta-analysis was to investigate the effect of pre-operative statins on perioperative outcomes in patients undergoing CEA for internal carotid artery (ICA) stenosis.

METHODS

A systematic review of PubMed, Medline, and the Cochrane Database of Systematic Reviews was performed. Studies were included which reported perioperative stroke and/or survival outcomes following CEA for ICA stenosis and compared patients who were and were not taking pre-operative statins. Relevant data were extracted and pooled using meta-analysis.

RESULTS

Seven studies met the inclusion criteria, comprising 21,387 patients. A total of 68.9% (14,976) were administered statins and 31.1% (6657) were statin-free. Pre-operative statin use was higher in patients with a history of cardiac disease (12.2 vs. 23.6% in the statin-free group), diabetes (31.6 vs. 25.1% in the statin-free group), and hypertension (83.5 vs. 72.2% in the statin-free group), while a greater proportion of statin-free patients had symptomatic disease (44.9 vs. 55.5% in the statin-free group). Statins were associated with reduced perioperative stroke in all patients (OR 0.57; 95% CI 0.34-0.95; p = 0.03) and in symptomatic patients (OR 0.57; 95% CI 0.35-0.93; p = 0.03). A trend towards lower perioperative mortality (OR 0.54; 95% CI 0.29, 1.03; p = 0.06) and significantly improved overall survival was observed in the statin group (HR 0.69; 95% CI 0.59-0.81; p < 0.001) at a mean follow-up of 62 months (range 27-76 months).

CONCLUSIONS

Administration of statins before CEA is associated with lower rates of perioperative stroke and improved overall survival. Compliance with optimal medical treatment associated with the use of pre-operative statins may limit the clinical significance of these findings. Future investigation to characterize the potential benefit of statin therapy in patients undergoing CEA for ICA stenosis is warranted.

Post-Operative Cognitive Dysfunction: An exploration of the inflammatory hypothesis and novel therapies

Post-Operative Cognitive Dysfunction (POCD) is a highly prevalent condition with significant clinical, social and financial impacts for patients and their communities. The underlying pathophysiology is becoming increasingly understood, with the role of neuroinflammation and oxidative stress secondary to surgery and anaesthesia strongly implicated. This review aims to describe the putative mechanisms by which surgery-induced inflammation produces cognitive sequelae, with a focus on identifying potential novel therapies based upon their ability to modify these pathways.

Diabetes is associated with risk of postoperative cognitive dysfunction: A meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) occurs frequently after surgery, particularly among older people. Diabetes, chronic hyperglycemia, and a history of hypoglycemia are related to cognitive impairment, but little is known about their roles in POCD. Here, we estimated their associations with risk of POCD on the basis of published epidemiological research.

METHODS

The PubMed and Cochrane databases were searched for longitudinal studies of adults undergoing surgery with reporting of associations of diabetes status, glycemic levels, and/or a history of hypoglycemia with risk of POCD as relative risks or odds ratios. Meta-analysis Of Observational Studies in Epidemiology (MOOSE) and Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed.

RESULTS

The search identified 246 publications of which 14 met inclusion criteria, reporting on a total of 2642 patients (mean age 64 y). Follow-up periods spanned 1 day to 5 years. Overall, patients with diabetes had a 1.26-fold higher risk of POCD compared with diabetes-free patients (95% CI, 1.12-1.42). A single study assessed glycemic control in patients with diabetes and identified a higher hemoglobin A1c (HbA1c) level as associated with higher POCD risk (relative risk per percent higher HbA1c, 2.0; 95% CI, 1.4-2.6). We did not find studies on glycemic levels in the nondiabetic range or on hypoglycemia as potential predictors of POCD.

CONCLUSION

Patients with diabetes appear to have a higher risk of POCD compared with diabetes-free persons. Among patients with diabetes, POCD risk may further increase with poorer glycemic control as indexed by higher HbA1c. The roles of HbA1c levels among nondiabetic persons in POCD risk warrant further research.

Hypertension and Risk of Post-Operative Cognitive Dysfunction (POCD): A Systematic Review and Meta-Analysis

Background:

Post-operative cognitive dysfunction (POCD) occurs frequently after major surgery. Hypertension is well-established as a risk factor for age-related cognitive impairment, but it is unclear whether or not it also increases the risk of POCD.

Objective:

To evaluate the role of hypertension in POCD risk in a systematic review and meta-analysis.

Method:

PubMed, Ovid SP and the Cochrane Database of Systematic Reviews were searched for longitudinal studies of adults undergoing surgery with reporting of hypertension, blood pressure and/or anti-hypertensive treatment associations with POCD as relative risks or odds ratios. Fixed-effects meta-analyses were performed using Review Manager (version 5.3).

Results:

Twenty-four studies on 4317 patients (mean age 63 years) were included. None of the studies had set out to assess hypertension as a risk factor for POCD. Hypertension was used as a categorical predictor throughout and only 2 studies adjusted for potential confounders. Across all 24 studies, hypertension was not significantly associated with POCD risk (RR 1.01; 95% CI 0.93, 1.09; p=0.82), though among 8 studies with >75% males, we found hypertension associations with a 27% increased risk of POCD (RR 1.27, 95% CI 1.07, 1.49; p=0.005).

Conclusion:

Our findings do not support the hypothesis that hypertension is a risk factor for POCD. However, since none of the studies included in our analysis were hypothesis-driven and most did not adjust for potential confounders, further systematic investigations are needed to evaluate the role of hypertension in the epidemiology of POCD.

Spies C, Pischon T. Cognitive Reserve and the Risk of Postoperative Cognitive Dysfunction

BACKGROUND

Post-operative cognitive dysfunction (POCD) occurs in 10 to 54% of older patients during the first few weeks after surgery, but little is known about risk factors predisposing to POCD.

METHODS

Systematic literature review and meta-analysis of cognitive reserve indicators and POCD risk.

RESULTS

Fifteen studies on 5104 patients were included. Follow-up periods spanned 1 day to 6 months. Educational level was the most commonly assessed cognitive reserve indicator, and a longer time spent in education was associated with a reduced risk of POCD (relative risk [RR] per year increment 0.90; 95% confidence interval: [0.87; 0.94]), i.e. each year increase in education was associated with a 10% reduced risk. Similar findings were made for some analyses on education as a categorical predictor (high school versus further/higher education, RR 1.71, [1.30; 2.25]; lower than high school versus further/higher education, RR 1.69, [1.17; 2.44]) though risk was equivalent for patients with high school education and those with lower than high school education (RR 1.02; [0.78; 1.32]).

CONCLUSION

Patients with a relatively higher level of education are at reduced risk of POCD. Risk stratification of surgical patients according to educational level may prove useful.

Obesity and post-operative cognitive dysfunction: a systematic review and meta-analysis

BACKGROUND

Post-operative cognitive dysfunction, a condition distinct from post-operative delirium (POD), occurs frequently after surgery, and is related to dementia and premature death. Obesity increases the risk of late-life cognitive impairment, but little is known about its role in post-operative cognitive dysfunction. We conducted a systematic review and meta-analysis of studies on the association between obesity and risk of post-operative cognitive dysfunction.

METHODS

PubMed and the Cochrane Library were systematically searched. Studies were included if they had prospective designs, reported on human adults undergoing surgery, if cognitive function was measured pre- and post-surgery, if obesity, body mass index (BMI) and/or body weight were ascertained, and if associations with post-operative cognitive dysfunction were reported as relative risks or odds ratios. Underweight, weight loss, and post-operative delirium were not considered.

RESULTS

Inclusion criteria were met by six articles. Samples totaled 1432 older patients (mean age ≥62 years) who were followed up for 24 h to 12 months after surgery. Analysis of studies with obesity defined as a categorical measure found a non-significantly higher risk of post-operative cognitive dysfunction among persons with BMI > 30 kg/m(2) versus ≤30 kg/m(2) (relative risk 1.27; 95% confidence interval 0.95, 1.70; p = 0.10). No such associations were found for studies that analysed BMI or body weight continuously as predictors of post-operative cognitive dysfunction (relative risk 0.98 per kg/m(2) ; 95% confidence interval 0.93, 1.03, p = 0.45; relative risk 0.99 per kg; 95% confidence interval 0.89, 1.09; p = 0.83, respectively).

CONCLUSIONS

Few studies have addressed the topic, and the results of these studies provide only limited support for an increased risk of post-operative cognitive dysfunction in patients who are obese. Further large-scale, prospective investigations are necessary for clarification. Copyright © 2016 John Wiley & Sons, Ltd.