Postoperative Outcomes in Elderly Patients Undergoing Cardiac Surgery With Preoperative Cognitive Impairment

A Systematic Review and Meta-Analysis

Emily Au, BSc; Gowtham Thangathurai, BHSc; Aparna Saripella, MSc; Ellene Yan, HBSc; Marina Englesakis, MLIS; Mahesh Nagappa, MBBS; Frances Chung, MBBS, MD, FRCPC

Disclosures

Anesth Analg. 2023;136(6):1016-1028.

Abstract and Introduction

Abstract

Background: Older patients with preoperative cognitive impairment are at risk for increased postoperative complications after noncardiac surgery. This systematic review and meta-analysis aimed to determine the association between preoperative cognitive impairment and dementia and postoperative outcomes in older surgical patients after cardiac surgery.

Methods: Eight electronic databases were searched from inception to January 4, 2022. Inclusion criteria were cardiac surgery patients ≥60 years of age; preoperative cognitive impairment; ≥1 postoperative complication reported; comparator group with no preoperative cognitive impairment; and written in English. Using a random-effects model, we calculated effect sizes as odds ratio (OR) and standardized mean differences (SMDs). Risk of random error was assessed by applying trial sequential analysis.

Results: Sixteen studies (62,179 patients) were included. Preoperative cognitive impairment was associated with increased risk of delirium in older patients after cardiac surgery (70.0% vs 20.5%; OR, 8.35; 95% confidence interval [CI], 4.25–16.38; I², 0%; P < .00001). Cognitive impairment was associated with increased hospital length of stay (LOS; SMD, 0.36; 95% CI, 0.20–0.51; I², 22%; P < .00001) and intensive care unit (ICU) LOS (SMD, 0.39; 95% CI, 0.09–0.68; I², 70%; P = .01). No significant association was seen for 30-day mortality (1.7% vs 1.1%; OR, 2.58; 95% CI, 0.64–10.44; I², 55%; P = .18).

Conclusions: In older patients undergoing cardiac surgery, cognitive impairment was associated with an 8-fold increased risk of delirium, a 5% increase in absolute risk of major postoperative bleeding, and an increase in hospital and ICU LOS by approximately 0.4 days. Further research on the feasibility of implementing routine neurocognitive testing is warranted.

Introduction

The proportion of older patients (≥65 years of age) undergoing surgery in industrialized nations has been rising in recent decades.^[1,2] It is estimated that approximately 30% to 50% of older surgical patients have preoperative cognitive impairment.^[3] Despite the high prevalence of cognitive impairment in the aging population, baseline cognition is not routinely assessed in the preoperative setting. Cognitive impairment encompasses a spectrum of neurocognitive disorders (NCDs), ranging from mild cognitive impairment or mild NCD, in which independence with activities of daily living (ADLs) is preserved, to dementia or major NCD, in which major ADLs are significantly compromised.^[4] A recent systematic review and meta-analysis found that preoperative cognitive impairment in older noncardiac surgical patients was associated with increased risk of postoperative delirium (POD), 1-year mortality, 30-day readmissions, and postoperative complications.^[5]

Cardiovascular disease has been identified as the leading cause of morbidity and mortality in the older population, with an increasing number of patients requiring cardiac surgery.^[6,7] Cardiac surgery varies in invasiveness and complexity, ranging from minimally invasive surgery (ie, transcatheter valve replacement [TAVR]), to open heart surgery involving coronary artery bypass graft (CABG). More invasive cardiac surgeries are associated with systemic inflammation and a high prevalence of postoperative complications.^[8]

The overall impact of preoperative cognitive impairment on postoperative outcomes after various cardiac surgeries is not fully known. This systematic review and meta-analysis aims to evaluate the association between cognitive impairment and postoperative outcomes in older patients undergoing cardiac surgery. To minimize adverse outcomes, preoperative neurocognitive screening may help identify at-risk individuals, who require closer monitoring, additional interventions, and more excellent follow-up care.

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Next Section

Abstract and Introduction
Methods
Results
Discussion
Conclusions
References
Sidebar

Table 1. Demographics and Study Characteristics of Cognitively Impaired and Dementia Patients Undergoing Elective Cardiac Surgeries
First author, year, country	Type of surgery	Study design	Total patients (N)	Age (y)	Sex (female), n (%)	Preoperative cognitive impairment prevalence, n (%)	Cognitive assessment test and cutoff
Cognitive impairment
Mixed cardiac surgery
Itagaki et al,²² 2020, Japan	Mixed^a	RC	89	74.9 ± 5.5	32 (35.9)	55 (61.8)	MoCA <26
Boureau et al,²³ 2018, France^b	Mixed	RC	197	81.35 ± 3.5	102 (51.8)	29 (14.7)	MMSE <24
Terazawa et al,²⁴ 2018, Japan	Mixed	PC	490	71.9 ± 7.2	160 (32.7)	51 (10.4)	MMSE <24
Harrington et al,²⁵ 2011, USA	Mixed	RC	181	68.1 ± 10.7	2 (1.0)	52 (29.0)	CIB ≤5
Maekawa et al,²⁶ 2011, Japan	Mixed^a	PC	362	69.5 ± 9.7	141 (39.0)	40 (11.0)	HDS <24
Veliz-Reissmüller et al,²⁷ 2007, Sweden	Mixed	PC	107	71.6 ± 6.0	41 (38.3)	4 (3.7)	MMSE <25
CABG surgery
Kazmierski et al,²⁸ 2014, UK^c	CABG	PC	113	64 ± 8.9	23 (20.4)	CI: 28 (24.8); dementia: 6 (5.3)	CI: MoCA <26; dementia: DSM-IV-TR criteria
Aykut et al,²⁹ 2013, Turkey	CABG	PC	48	71.4 ± 3.7	26 (54.0)	25 (52.0)	MoCA <26
Baba et al,³⁰ 2007, Japan	CABG^d	PC	218	71.2 ± 5.5	66 (30.3)	14 (6.4)	HDS <24
Millar et al,³¹ 2001, UK	CABG	PC	81	76.4 ± 24.4	17 (21.0)	13 (16.0)	Stroop neurological screening test
TAVI/TAVR
Luque et al,³² 2021, Spain	TAVR	PC	501	83.5 ± 5.0	289 (57.7)	18 (3.6)	MMSE <24
Kapadia et al,³³ 2020, USA	TAVR	PC	142	84.2 ± 6.0	69 (48.6)	46 (32.4)	MMSE <24
Saji et al,³⁴ 2019, Japan	TAVR	PC	455	84.5 ± 5.0	309 (67.9)	177 (38.9)	HDS-R <24
Yanagisawa et al,³⁵ 2018, Japan	TAVI	PC	1111	85.0 ± 5.2	791 (71.2)	420 (38.0	MMSE <25
Schoenenberger et al,³⁶ 2016, Switzerland	TAVI	PC	279 (cognitive impairment data available for 229)	83.5 ± 4.3	161 (57.7)	63 (22.6)	MMSE <26
Dementia
TAVR
Jain et al,²³ 2021, USA	TAVR	RC	57,805	82.3 ± 6.4	27,685 (47.9)	2910 (5.0)	Previous dementia diagnosis (ICD codes)

Abbreviations: CABG, coronary artery bypass graft surgery; CIB, Clock-in-the-Box; CPB, cardiopulmonary bypass; DSM-IV-TR, Diagnostic and Statistical Manual of Mental Disorders, 4th ed text revision; HDS, Hasegawa Dementia Score; HDS-R, Hasegawa Dementia Score revised; ICD, International Classification of Diseases; MMSE, Mini-Mental Status Examination; MoCA, Montreal Cognitive Assessment; PC, prospective cohort; RC, retrospective cohort; TAVI, transcatheter aortic valve implantation; TAVR, transcatheter aortic valve replacement.
^aMixed surgery: CABG, valve repair/replacement, and thoracic aneurysm repair.
^bIncludes some percentage of emergency surgeries.
^cIncludes some percentage of dementia patients.
^dIncludes some percentage of off-pump CABG surgery.

Table 2. Other Postoperative Outcomes.
First author, year, country	Type of surgery	Cognitive impairment, %	No cognitive impairment, %	Postoperative major complications	Postoperative delirium	LOS	Nonhome discharge	Cognitive deterioration
Itagaki et al,²² 2020, Japan	Mixed cardiac	61.8	31.9	NR	OR, 3.11 (1.04–9.32)	NR	NR	NR
Terazawa et al,²⁴ 2018, Japan	Mixed cardiac	10.4	89.6	OR, 3.02 (1.30–7.03)^a	OR, 2.26 (1.04–1.13)^a	NR	OR, 2.39 (1.07–5.35)^a	NR
Harrington et al,²⁵ 2011, USA	Mixed cardiac	29.0	71.0	NR	NR	NR	HR, 0.93 (0.89–0.98)^a	NR
Maekawa et al,²⁶ 2011, Japan	Mixed cardiac	11.0	89.0	NR	NR	NR	NR	NR
Veliz-Reissmüller et al,²⁷ 2007, Sweden	Mixed cardiac	3.7	96.3	NR	NR	NR	NR	NR
Kazmierski et al,²⁸ 2014, UK	CABG	24.8	75.2	NR	OR, 6.33 (31.93–20.76)^a	NR	NR	NR
Aykut et al,²⁹ 2013, Turkey	CABG	52.0	48.0	NR	NR	NR	NR	NR
Baba et al,³⁰ 2007, Japan	CABG	6.4	93.6	NR	NR	NR	NR	NR
Millar et al,³¹ 2001, UK	CABG	16.0	84.0	NR	NR	NR	NR	NR
Luque et al,³² 2021, Spain	TAVR	3.6	96.4	NR	OR, 4.17 (1.11–15.71)^a	NR	NR	NR
Kapadia et al,³³ 2020, USA	TAVR	32.4	67.6	NR	NR	NR	NR	NR
Schoenenberger et al,³⁶ 2016, Switzerland	TAVI	22.6	77.4	NR	NR	NR	NR	OR, 0.87 (0.34–2.26)^a
Jain et al,³⁷ 2021, United States	TAVR	5.0	95.0	NR	OR, 2.13 (1.26–3.61)	OR, 1.11 (1.03–1.19)	OR, 2.27 (1.67–3.08)	NR

Mixed cardiac surgery: CABG, valve repair/replacement, and thoracic aneurysm repair.
Abbreviations: CABG; coronary artery bypass graft surgery; LOS, length of stay; NR, not reported; OR, odds ratio (95% confidence interval); HR, hazard ratio (95% confidence interval); TAVI, transcatheter aortic valve implantation; TAVR, transcatheter aortic valve replacement.
^aMultivariate analysis.

Table 3. Mortality Outcomes of Included Studies.
First author, year, country	Cognitive impairment, %	No cognitive impairment, %	In-hospital morality	30-day mortality	6-month mortality	1-year mortality
Terazawa et al,²⁴ 2018, Japan	10.4	89.6	OR, 5.72 (1.80–18.17)	NR	NR	NR
Boureau et al,²³ 2018, France	14.7	85.3	NR	NR	NR	HR, 2.47 (0.87–7.01)
Saji et al,³⁴ 2019, Japan	38.9	61.1	NR	HR, 2.11 (1.21–3.69)^a	NR	NR
Yanagisawa et al,³⁵ 2018, Japan	38.0	62.0	NR	NR	NR	HR, 2.1 (1.10–4.00)^a
Schoenenberger et al,³⁶ 2016, Switzerland	22.6	77.4	NR	NR	NR	NR
Jain et al,³⁷ 2021, United States	5.0	95.0	OR, 1.26 (0.57–2.79)	NR	NR	NR

Abbreviations: CI, confidence interval; HR, hazard ratio (95% CI); NR, not reported; OR, odds ratio (95% CI).
^aMultivariate analysis.

Authors and Disclosures

Emily Au, BSc*, Gowtham Thangathurai, BHSc†, Aparna Saripella, MSc*, Ellene Yan, HBSc*‡, Marina Englesakis, MLIS§, Mahesh Nagappa, MBBS|| and Frances Chung, MBBS, MD, FRCPC*

*Department of Anesthesia and Pain Management, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada; †Department of Medicine, McGill University, Montreal, Quebec, Canada; ‡Department of Medical Science, University of Toronto, Toronto, Ontario, Canada; §Department of Library & Information Services, University Health Network, Toronto, Ontario, Canada; and ||Department of Anesthesia and Perioperative Medicine, London Health Sciences Centre and St Joseph Health Care, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.

Address correspondence to
Frances Chung, MBBS, MD, FRCPC, Department of Anesthesia and Pain Medicine, Toronto Western Hospital, University Health Network, University of Toronto, 399 Bathurst St, Toronto, ON M5T 2S8, Canada. Address e-mail to frances.chung@uhn.ca.

Disclosures
Name: Emily Au, BSc.
Contribution: This author helped with study conception and design, acquiring and interpreting study data, and writing the manuscript.
Conflicts of Interest: None.
Name: Gowtham Thangathurai, BHSc.
Contribution: This author helped acquire and interpret study data and write the manuscript.
Conflicts of Interest: None.
Name: Aparna Saripella, MSc.
Contribution: This author helped acquire study data and with statistical analysis.
Conflicts of Interest: None.
Name: Ellene Yan, HBSc.
Contribution: This author helped acquire study data.
Conflicts of Interest: None.
Name: Marina Englesakis, MLIS.
Contribution: This author helped develop the search strategy.
Conflicts of Interest: None.
Name: Mahesh Nagappa, MBBS.
Contribution: This author helped with statistical analysis and writing the manuscript.
Conflicts of Interest: M. Nagappa reports grants from the Academic Medical Organization of Southwestern Ontario Opportunity Fund, Ontario Ministry of Health and Long-Term Care Innovation Fund, and Lawson Research Fund.
Name: Frances Chung, MBBS, MD, FRCPC.
Contribution: This author helped with study conception and design, interpreting study data, and writing the manuscript.
Conflicts of Interest: F. Chung reports research support from the University Health Network Foundation, ResMed Foundation, consultant to Takeda Pharma, Up-to-Date royalties, and STOP-Bang proprietary to University Health Network.
This manuscript was handled by: Stefan G. De Hert, MD.