The Relevance of Postoperative Cognitive Decline in Daily Living: Results of a 1-Year Follow-up

Patient-Reported Postoperative Neuropsychological Deterioration After Heart Valve Replacement and Coronary Artery Bypass Grafting

Background

Postoperative cognitive decline (POCD) after cardiosurgical interventions are well described through objective psychometric tests. However, a patient's subjective perception is essential to clinical assessment and quality of life. This study systematically evaluated patient-reported POCD between subjects undergoing coronary artery bypass grafting and heart valve replacement.

Methods

This study was a multicentre, prospective questionnaire survey conducted at the cardiac surgery departments at the Kerckhoff Clinic in Bad Nauheim and the University Hospital in Giessen, Germany. We included patients undergoing elective coronary artery bypass grafting (CABG), aortic valve replacement (AVR), mitral valve replacement or reconstruction (MVR), and combined surgery (CABG + valve replacement [VR]) with extracorporeal circulation. The Hospital Anxiety and Depression Scale, the Cognitive Failures Questionnaire (CFQ) for Self-assessment (CFQ-S), and the external assessment (CFQ-foreign [F]) were completed preoperatively, as well as at 3 and 12 months postoperatively.

Results

A total of 491 patients were available for analyses (CABG = 182, AVR = 134, MVR = 93, CABG + VR = 82). POCD and postoperative depression increase (PODI) were observed for each surgical procedure. (At the 3-month follow-up: CFQ-S [CABG = 7.1%, AVR = 3.7%, MVR = 9.7%, CABG + VR = 9.8%]; CFQ-F [CABG = 9.9%, AVR = 9.7%, MVR = 9.7%, CABG + VR = 15.9%]; PODI [CABG = 7.7%, AVR = 9.7%, MVR = 6.5%, CABG + VR = 8.5%]. At the 12-month follow-up: CFQ-S [CABG = 6.6%, AVR = 7.5%, MVR = 15.1%, CABG + VR = 7.3%]; CFQ-F [CABG = 7.1%, AVR = 14.9%, MVR = 10.8%, CABG + VR = 9.8%]; PODI [CABG = 10.4%, AVR = 11.2%, MVR = 6.5%, CABG + VR = 4.9%]). No significant between-group effects were observed for the CFQ-S, CFQ-F, or the Hospital Anxiety and Depression Scale.

Conclusions

For clinicians, paying attention to patients' self-reported experiences of reduced cognitive function and symptoms of depression following cardiac surgery is important. Such reporting is an indication that interventions such as cognitive training or psychotherapy should be considered.

Cognitive reserve and the risk of postoperative neurocognitive disorders in older age

Background

Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) are postoperative neurocognitive disorders (PNDs) that frequently occur in the aftermath of a surgical intervention. Cognitive reserve (CR) is a concept posited to explain why cognitive health varies between individuals. On this qualitative understanding of cognitive health, factors like IQ, education level, and occupational complexity can affect the impact of neuropathological processes on cognitive outcomes.

Methods

We investigated the association between CR and POD and CR and POCD on data from 713 patients aged≥65 years with elective surgery. Peak pre-morbid IQ was estimated from vocabulary. Occupational complexity was coded according to the Dictionary of Occupational Titles (DOT). Education level was classed according to the International Standard Classification of Education (ISCED). These three factors were used as proxies of CR. In a series of regression models, age, sex, depression, site of surgery, and several lifestyle and vascular factors were controlled for.

Results

Patients with a higher IQ had lower odds of developing POD. We found no significant association between the other two CR markers with POD. None of the CR markers was associated with POCD.

Conclusion

The significant association of a higher IQ with lower POD risk allows for the stratification of elderly surgical patients by risk. This knowledge can aid the prevention and/or early detection of POD. Further research should attempt to determine the lack of associations of CR markers with POCD in our study.

Twelve-month follow-up effects of cognitive training after heart valve surgery on cognitive functions and health-related quality of life: a randomised clinical trial

OBJECTIVES

Postoperative cognitive decline (POCD) or decreased health-related quality of life (HQL) have been reported after cardiac surgery. A previous investigation showed beneficial effects of postoperative cognitive training on POCD and HQL 3 months after heart surgery. Here, we present the 12-month follow-up results.

METHODS

This bicentric, 1:1 randomised and treatment-as-usual controlled trial included elderly patients scheduled for elective heart valve surgery. The training consisted of paper-and-pencil-based exercises practising multiple cognitive functions for 36 min/day 6 days/week over a period of 3 weeks. Neuropsychological tests and questionnaires assessing HQL (36-Item Short Form Health Survey (SF-36)) and cognitive failures in daily living (Cognitive Failures Questionnaire) were performed presurgery and 12 months after training.

RESULTS

Twelve months post training, the training group (n=30) showed improvements in HQL compared with the control group (n=28), especially in role limitations due to physical health (U=-2.447, p=0.015, η2=0.109), role limitations due to emotional problems (U=-2.245, p=0.025, η2=0.092), pain (U=-1.979, p=0.049, η2=0.068), average of all SF-36 factors (U=-3.237, p<0.001, η2=0.181), health change from the past year to the present time (U=-2.091, p=0.037, η2=0.075), physical component summary (U=-2.803, p=0.005, η2=0.138), and mental component summary (U=-2.350, p=0.018, η2=0.095). Furthermore, the training group (n=19) showed an improvement compared with the control group (n=27) in visual recognition memory (U=-2.137, p=0.034, η2=0.099). POCD frequency was 22% (n=6) in the control group and 11% (n=2) in the training group (χ²(1) =1.06, p=0.440; OR=2.43, 95% CI 0.43 to 13.61).

CONCLUSION

In conclusion, postoperative cognitive training shows enhancing effects on HQL in cardiac surgery patients after 12 months.

The impact of postoperative cognitive training on health-related quality of life and cognitive failures in daily living after heart valve surgery: A randomized clinical trial

BACKGROUND

Heart surgery is a risk factor for objectively and subjectively assessable postoperative cognitive decline (POCD), which is relevant for everyday life. The aim of this study was to investigate whether early postoperative cognitive training has an impact on health-related quality of life and cognitive failures in daily living after cardiac surgery.

METHODS

The study was a two-arm, randomized, controlled, outcome-blinded trial involving older patients undergoing elective heart valve surgery with extracorporeal circulation (ECC). Recruitment took place at the Departments of Cardiac Surgery of the Kerckhoff Clinic in Bad Nauheim (Germany) and the University Hospital in Giessen (Germany). The patients were randomized (1:1 ratio) to either a paper-and-pencil-based cognitive training group or a control group. We applied the Short Form Health Survey (SF-36) and the Cognitive Failures Questionnaire (CFQ) prior to surgery and 3 months after the cognitive training. Data were analyzed in a per-protocol fashion.

RESULTS

Three months after discharge from rehabilitation, the training group (n = 31) showed improvement in health-related quality of life compared to the control group (n = 29), especially in role limitations due to emotional problems (U = -2.649, p = .008, η²  = 0.121), energy and fatigue (F[2.55] = 5.72, p = .020, η²  = 0.062), social functioning (U = -2.137, p = .033, η²  = 0.076), the average of all SF-36 factors (U = -2.374, p = .018, η²  = 0.094), health change from the past year to the present time (U = -2.378, p = .017, η²  = 0.094), and the mental component summary (U = -2.470, p = .013, η²  = 0.102).

CONCLUSION

As our cognitive training has shown beneficial effects, this intervention could be a promising method to enhance health-related quality of life after cardiac surgery.

Increasing preoperative cognitive reserve to prevent postoperative delirium and postoperative cognitive decline in cardiac surgical patients (INCORE): Study protocol for a randomized clinical trial on cognitive training

Introduction

Postoperative delirium (POD) and postoperative cognitive decline (POCD) can be observed after cardiosurgical interventions. Taken together, these postoperative neurocognitive disorders (PNCDs) contribute to increased morbidity and mortality. Preoperative risk factors of PNCD, such as decreased neuropsychometric performance or decreased cognitive daily activities, can be interpreted as reduced cognitive reserve. This study aims to build up cognitive reserves to protect against the development of PNCD through preoperative, home-based, cognitive training.

Methods

The planned research project is a monocentric, two-arm randomized controlled intervention study involving 100 patients undergoing elective cardiac surgery with extracorporeal circulation. Patients will be assigned to a training group or control group. The intervention involves a standardized, paper-and-pencil-based cognitive training that will be performed by the patients at home for ~40 min per day over a preoperative period of 2-3 weeks. The control group will receive neither cognitive training nor a placebo intervention. A detailed assessment of psychological functions will be performed ~2-3 weeks before the start of training, at the end of the training, during hospitalization, at discharge from the acute clinic, and 3 months after surgery. The primary objective of this study is to investigate the interventional effect of preoperative cognitive training on the incidence of POD during the stay in the acute clinic, the incidence of POCD at the time of discharge from the acute clinic, and 3 months after surgery. Secondary objectives are to determine the training effect on objective cognitive functions before the surgery and subjective cognitive functions, as well as health-related quality of life 3 months after surgery.

Discussion

Should it become evident that the use of our cognitive training can both reduce the incidence of POCD and POD and improve health-related quality of life, this intervention may be integrated into a standardized prehabilitation program.

Effects of postoperative cognitive training on neurocognitive decline after heart surgery: A randomized clinical trial

OBJECTIVES

Following cardiac surgery, postoperative cognitive decline (POCD) is a common complication that can impair quality of life and increase mortality. The aim of this study was to investigate whether early postoperative cognitive training can decrease POCD after cardiac surgery.

METHODS

The study was a multi-centered, 2-arm, randomized (1:1 ratio), controlled trial involving older patients undergoing elective heart valve surgery with extracorporeal circulation. Recruitment took place at the Departments of Cardiac Surgery of the Kerckhoff-Clinic in Bad Nauheim (Germany) and the University-Hospital in Giessen (Germany). The patients were randomized to either a paper-and-pencil-based cognitive training group or a standard rehabilitation care control group. The cognitive training started 1 week after surgery and lasted about 3 weeks until discharge from rehabilitation. To detect POCD, neuropsychological functions were assessed prior to surgery, upon discharge from rehabilitation (primary outcome), and 3 months after discharge (secondary outcome). Data were primarily analyzed in a per-protocol fashion.

RESULTS

The frequency of POCD at discharge from rehabilitation (training group, n = 37; control group, n = 44) was 50% in the control group and 19% in the training group (χ2[1]=8.45, p = 0.004; OR = 4.29, 95% CI [1.56-11.80]). Three months after the cognitive training (training group, n = 33; control group, n = 34), POCD frequency was 29% in the control group and 6% in the training group (χ2[1]=6.21, p = 0.013; OR = 6.46, 95% CI [1.29-32.28]).

CONCLUSIONS

Since our cognitive training showed beneficial effects, it could be a promising method to prevent POCD.

Biomarkers of Cerebral Injury for Prediction of Postoperative Cognitive Dysfunction in Patients Undergoing Cardiac Surgery

OBJECTIVES

To assess the ability of the biomarkers neuron-specific enolase (NSE), tau, neurofilament light chain (NFL), and glial fibrillary acidic protein (GFAP) to predict postoperative cognitive dysfunction (POCD) at discharge in patients who underwent cardiac surgery.

DESIGN

Post hoc analyses (with tests being prespecified before data analyses) from a randomized clinical trial.

SETTING

Single-center study from a primary heart center in Denmark.

PARTICIPANTS

Adult patients undergoing elective or subacute on-pump coronary artery bypass grafting and/or aortic valve replacement.

INTERVENTIONS

Blood was collected before induction of anesthesia, after 24 hours, after 48 hours, and at discharge from the surgical ward. The International Study of Postoperative Cognitive Dysfunction test battery was applied to diagnose POCD at discharge and after three months. Linear mixed models of covariance were used to assess whether repeated measurements of biomarker levels were associated with POCD. Receiver operating characteristic (ROC) curves were applied to assess the predictive value of each biomarker measurement for POCD.

MEASUREMENTS AND MAIN RESULTS

A total of 168 patients had biomarkers measured at baseline, and 47 (28%) fulfilled the POCD criteria at discharge. Patients with POCD at discharge had significantly higher levels of tau (p = 0.02) and GFAP (p = 0.01) from baseline to discharge. The biomarker measurements achieving the highest area under the ROC curve for prediction of POCD at discharge were NFL measured at discharge (AUC, 0.64; 95% confidence interval [CI], 0.54-0.73), GFAP measured 48 hours after induction (AUC, 0.64; 95% CI, 0.55-0.73), and GFAP measured at discharge (AUC, 0.64; 95% CI, 0.54-0.74), corresponding to a moderate predictive ability.

CONCLUSIONS

Postoperative serum levels of tau and GFAP were elevated significantly in patients with POCD who underwent cardiac surgery at discharge; however, the biomarkers achieved only modest predictive abilities for POCD at discharge. Postoperative levels of NSE were not associated with POCD at discharge.

Health-related quality of life and self-reported cognitive function in patients with delayed neurocognitive recovery after radical prostatectomy: a prospective follow-up study

Background

Delayed neurocognitive recovery (DNCR) is a common and serious complication after radical prostatectomy. We hypothesized that patients with DNCR in the early postoperative period would report reduced health-related quality of life (HRQoL) and more cognitive failures 12 months after surgery, compared with patients without DNCR.

Methods

We performed a 12-month follow-up on 367 patients who had been enrolled in a prospective observational trial to study the incidence of DNCR after radical prostatectomy. Patients were screened for preoperative cognitive impairment and depression. We defined DNCR as a decline in cognitive function between days 3 and 5 after surgery, compared with baseline assessments. We evaluated HRQoL and cognitive failures 12 months after surgery with the 36-item Short Form Health Survey and the Cognitive Failures Questionnaire. General linear models were used to analyze associations of DNCR with HRQoL and cognitive failures.

Results

Delayed neurocognitive recovery in the early postoperative period was significantly associated with self-reported cognitive failures (B for no DNCR =  − 0.411 [95% CI: − 0.798;0.024], p = 0.038), but not with physical (B = 0.082 [95% CI: − 0.021;0.186], p = 0.118) or mental HRQoL (B =  − 0.044 [95% CI: − 0.149;0.062], p = 0.417) 12 months after surgery. Preoperative depression screening scores were significantly associated with self-reported cognitive failures and both physical and mental HRQoL 12 months after surgery.

Conclusions

Delayed neurocognitive recovery in the early period after radical prostatectomy has a long-term impact on patients’ daily lives by impairing memory, attention, action, and perception. Therefore, prevention of DNCR must be a priority for physicians and researchers. Consequent preoperative screening for depressive symptoms may facilitate early psycho-oncological intervention to improve postoperative HRQoL.

Trials registrationDRKS00010014, date of registration: 21.03.2016, retrospectively registered.

Lower preoperative hematocrit, longer hospital stay, and neurocognitive decline after cardiac surgery

BACKGROUND

Cardiopulmonary bypass may be associated with postoperative neurocognitive dysfunction; however, risk factors have not been clearly identified. We hypothesize that lower hematocrit levels are correlated with postoperative neurocognitive dysfunction.

METHODS

A total of 30 patients underwent cardiac operations utilizing cardiopulmonary bypass and screening for neurocognitive dysfunction preoperatively and on postoperative day 4. Patients were analyzed according to hematocrit preoperatively, 6 hours postoperatively, and on postoperative day 4, and whether they received intra or postoperative transfusions of packed red blood cells. Neurocognitive data is presented as a difference in Repeatable Battery for the Assessment of Neuropsychological Status standardized score from baseline to postoperative day 4 and analyzed by unpaired two-tailed Spearman test and unpaired Mann-Whitney U test.

RESULTS

There was a significant correlation between patients with lower hematocrit before surgery and a decline in neurocognitive function at postoperative day 4 (P < .05). All patients experienced a decrease in hematocrit during their hospital stay, but the hematocrit 6 hours postoperatively and postoperative day 4 did not impact cognition. Receiving a transfusion was also not associated with neurocognitive dysfunction. Patients with low hematocrit preoperatively had a consistently lower hematocrit throughout their stay. Prolonged total length of stay was also significantly associated with neurocognitive decline.

CONCLUSION

A lower preoperative hematocrit and prolonged length of hospital stay are correlated with neurocognitive decline after cardiac surgery utilizing cardiopulmonary bypass.

Decreasing postoperative cognitive deficits after heart surgery: protocol for a randomized controlled trial on cognitive training

Background

The occurrence of postoperative cognitive deficits, especially after heart surgery, has been demonstrated in several studies. These deficits can clearly be noticed by the patients and by their close relatives in daily life. Furthermore, postoperative cognitive deficits can decrease quality of life in social functioning and earning capacity. The aim of this study is to investigate whether early postoperative cognitive training can reduce subjective and objective postoperative cognitive deficits.

Methods

The proposed study is a multicenter, two-arm, randomized controlled trial involving 144 elderly patients undergoing elective heart-valve surgery with extracorporeal circulation. Patients will be assigned to either a training group or a control group. The intervention involves paper-and-pencil-based cognitive training, which is conducted for 36 min over a period of 18 days. The training starts about 1 week after surgery and is carried out during the hospitalized rehabilitation phase. The control group will not receive cognitive training or a placebo intervention. A detailed assessment of psychological functions and health-related quality of life prior to surgery at discharge from rehabilitation and 3 and 12 months after discharge will be performed. The primary outcome of this trial is the training effect on objective cognitive functions at discharge from rehabilitation. Secondary outcomes are the training effect on objective and subjective cognitive functions (3 and 12 months after discharge), depression, health-related quality of life, and the impact of perioperative cerebral ischemia on the training effect. Perioperative cerebral ischemia will be measured with postoperative magnetic resonance imaging including diffusion-weighted sequences.

Discussion

Should it be shown that our cognitive training can improve postoperative cognitive deficits and quality of life, one possibility could be to integrate this intervention into early rehabilitation. Furthermore, we hope that the investigation of perioperative ischemia by diffusion-weighted magnetic resonance imaging will improve our understanding of neurobiological factors influencing the course of postoperative cognitive plasticity.

Trial registration

German Clinical Trials Register (DRKS), DRKS00015512. Retrospectively registered on 21 September 2018.

Cognitive Outcomes After Heart Valve Surgery: A Systematic Review and Meta-Analysis

OBJECTIVES

To summarize evidence on cognitive outcomes after heart valve surgery; secondary aim, to examine whether aortic and mitral valve surgery are associated with different cognitive outcomes.

DESIGN

Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic review and meta-analysis.

SETTING

Cardiac surgery.

PARTICIPANTS

Individuals undergoing heart valve surgery.

MEASUREMENTS

We searched MEDLINE, EMBASE, and PsycINFO for peer-reviewed reports of individuals undergoing heart valve surgery who underwent pre- and postoperative cognitive assessment. Our initial search returned 1,475 articles, of which 12 were included. Postoperative cognitive results were divided into those from 1 week to 1 month (early outcomes, n_pooled  = 450) and from 2 to 6 months (intermediate outcomes; n_pooled  = 722). No studies with longer-term outcomes were identified.

RESULTS

Subjects had moderate early cognitive decline from baseline (Becker mean gain effect size (ES)=-0.39 ± 0.27) that improved slightly by 2 to 6 months (ES=-0.25 ± 0.38). Individuals undergoing aortic valve surgery-who were older on average than those undergoing mitral valve surgery (68 vs 57)-had greater early cognitive decline than those undergoing mitral valve surgery (ES=-0.68 vs -0.12), but both cohorts had similar decline 2 to 6 months postoperatively (ES=-0.27 vs -0.20).

CONCLUSIONS

Heart valve surgery is associated with cognitive decline over the 6 months after surgery, but outcomes beyond 6 months are unclear. These findings highlight the cognitive vulnerability of this population, especially older adults with aortic stenosis. © 2018 American Geriatrics Society and Wiley Periodicals, Inc. J Am Geriatr Soc 66:2327-2334, 2018.

Ability of postoperative delirium to predict intermediate-term postoperative cognitive function in patients undergoing elective surgery at an academic medical centre: protocol for a prospective cohort study

INTRODUCTION

Postoperative delirium (POD) is a common complication in elderly patients, characterised by a fluctuating course of altered consciousness, disordered thinking and inattention. Preliminary research has linked POD with persistent cognitive impairment and decreased quality of life. However, these findings maybe confounded by patient comorbidities, postoperative complications and frailty. Our objective is to determine whether POD is an independent risk factor for persistent impairments in attention and executive function after elective surgery. Our central hypothesis is that patients with POD are more likely to have declines in cognition and quality of life 1 year after surgery compared with patients without POD. We aim to clarify whether these associations are independent of potentially confounding factors. We will also explore the association between POD and incident dementia.

METHODS AND ANALYSIS

This study will recruit 200 patients from the ongoing Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) study. Patients who live ≤45 miles from the study centre or have a planned visit to the centre 10-16 months postoperatively will be eligible. Patients with POD, measured by the Confusion Assessment Method, will be compared with patients without delirium. The primary outcome of cognitive function and secondary outcomes of quality of life and incident dementia will be compared between cohorts. Cognition will be measured by Trails A and B and Stroop Color and Word Test, quality of life with Veteran's RAND 12-item Health Survey and incident dementia with the Short Blessed Test. Multivariable regression analyses and a Cox proportional hazards analysis will be performed. All results will be reported with 95% CIs and α=0.05.

ETHICS AND DISSEMINATION

The study has been approved by the Washington University in St. Louis Institutional Review Board (IRB no 201601099). Plans for dissemination include scientific publications and presentations at scientific conferences.

TRIAL REGISTRATION NUMBER

NCT02241655.

Development and Validation of an Abbreviated Questionnaire to Easily Measure Cognitive Failure in ICU Survivors: A Multicenter Study

OBJECTIVES

To develop and validate an abbreviated version of the Cognitive Failure Questionnaire that can be used by patients as part of self-assessment to measure functional cognitive outcome in ICU survivors.

DESIGN

A retrospective multicenter observational study.

SETTING

The ICUs of two Dutch university hospitals.

PATIENTS

Adult ICU survivors.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cognitive functioning was evaluated between 12 and 24 months after ICU discharge using the full 25-item Cognitive Failure Questionnaire (CFQ-25). Incomplete CFQ-25 questionnaires were excluded from analysis. Forward selection in a linear regression model was used in hospital A to assess which of the CFQ-25 items should be included to prevent a significant loss of correlation between an abbreviated and the full CFQ-25. Subsequently, the performance of an abbreviated Cognitive Failure Questionnaire was determined in hospital B using Pearson's correlation. A Bland-Altman plot was used to examine whether the reduced-item outcome scores of an abbreviated Cognitive Failure Questionnaire were a replacement for the full CFQ-25 outcome scores. Among 1,934 ICU survivors, 1,737 were included, 819 in hospital A, 918 in hospital B. The Pearson's correlation between the abbreviated 14-item Cognitive Failure Questionnaire (CFQ-14) and the CFQ-25 was 0.99. The mean of the difference scores was -0.26, and 95% of the difference scores fell within +5 and -5.5 on a 100-point maximum score.

CONCLUSIONS

It is feasible to use the abbreviated CFQ-14 to measure self-reported cognitive failure in ICU survivors as this questionnaire has a similar performance as the full CFQ-25.

Influence of the postoperative inflammatory response on cognitive decline in elderly patients undergoing on-pump cardiac surgery: a controlled, prospective observational study

Background

The role of non-infective inflammatory response (IR) in the aetiology of postoperative cognitive dysfunction (POCD) is still controversial. The aim of this controlled, prospective observational study was to assess the possible relationship between the grade of IR, defined by procalcitonin (PCT) changes, and development of POCD related to cardiac surgery.

Methods

Forty-two patients, who were ≥ 60 years of age and scheduled for elective cardiac surgery, were separated into the low inflammatory (LIR) and high inflammatory (HIR) response groups based on their PCT levels measured on the first postoperative day. A matched normative control group of 32 subjects was recruited from primary care practice. The PCT and C-reactive protein (CRP) levels were monitored daily during the first five postoperative days. The cognitive function and mood state were preoperatively tested with a set of five neurocognitive tests and two mood inventories and at the seventh postoperative day. The Reliable Change Index modified for practice (RCIp) using data from normative controls was applied to determine the significant decline in test performance.

Results

The LIR (n = 20) and HIR (n = 22) groups differed significantly in the PCT (p < 0.001) but not in the CRP time courses. The incidence of POCD at the first postoperative week was 35.7% in the cohort. The LIR and HIR groups did not vary in the RCIp Z scores of neurocognitive tests and frequencies of POCD (7 vs 8 cases, respectively, p > 0.05). Additionally, there was no difference in the mood states, anxiety levels and perioperative parameters known to influence the development of POCD.

Conclusions

In this study, the magnitude of the non-infective inflammatory response generated by on-pump cardiac surgery did not influence the development of POCD in the early postoperative period in elderly patients.

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.