Abstract
Background
The efficacy of dexmedetomidine in preventing postoperative delirium (POD) following cardiac surgery remains controversial. This systematic review aimed to evaluate whether dexmedetomidine could prevent POD in patients undergoing cardiac surgery.
Methods
PubMed, CENTRAL, and Embase were searched up to 1 November 2024. Randomized controlled trials (RCTs) concerning dexmedetomidine for preventing POD in patients undergoing cardiac surgery were included. The primary outcome was the incidence of POD, and the secondary outcome was the incidence of postoperative atrial fibrillation (POAF). The analyses were performed using RevMan 5.3 and R 4.4.2 to calculate risk ratio (RR) with 95% confidence interval (CI). Trial sequential analysis (TSA) was conducted using TSA 0.9.5.10 Beta.
Results
Thirty-two studies with 6046 participants were included. Dexmedetomidine notably reduced the incidence of POD (RR = 0.67, 95% CI 0.59–0.76, P < 0.00001), with sufficient evidence and conclusive result from TSA. Dexmedetomidine was more effective in preventing POD compared with both positive control (RR = 0.47, 95% CI 0.38–0.59, P < 0.00001) and placebo control (RR = 0.83, 95% CI 0.70–0.98, P = 0.02). It reduced the incidence of POD not only in elderly patients (RR = 0.66, 95% CI 0.54–0.81, P < 0.0001) but also in normal age patients (RR = 0.68, 95% CI 0.57–0.80, P < 0.00001). Moreover, dexmedetomidine decreased the incidence of POAF (RR = 0.82, 95% CI 0.74–0.92, P = 0.0005).
Conclusions
Dexmedetomidine could reduce the incidence of POD in patients undergoing cardiac surgery and was associated with a decreased incidence of POAF. The findings should be interpreted with caution because of the low to moderate quality of evidence. Further trials are still needed to explore the optimal regimen of dexmedetomidine.
Registration number: INPLASY2024110008.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12871-025-03264-y.
Keywords: Dexmedetomidine, Postoperative delirium, Meta-analysis, Trial sequential analysis
Background
Postoperative delirium (POD) is defined as a disturbance in attention, awareness and cognition that typically emerges within 5 days after surgical procedures [1]. It is the most prevalent complication seen in patients undergoing cardiac surgery, with an occurrence rate ranging from 4.1 to 54.9% [2]. In particular, up to 50% of patients over 60 years old who undergo cardiac surgery may experience POD [3]. In addition to advanced age, postoperative atrial fibrillation (POAF) is also one of the significant risk factors associated with POD following cardiac surgery [2, 4]. It is widely recognized that the systemic inflammatory response triggered by preoperative disease status, cardiopulmonary bypass and myocardial ischemia–reperfusion injury can give rise to POD, and a neurotransmitter imbalance, specifically an increase in acetylcholine and a decrease in dopamine, is also related to POD [5]. The synthesized evidence indicated that POD was linked to poor prognosis among cardiac surgical patients, and was causally associated with a higher risk of mortality, extended durations of both ICU and hospital stays, as well as an increased length of mechanical ventilation [6]. These poor outcomes not only increase spending within the healthcare sector, but also impose significant social costs as families bear the increased burden of time and financial resources to care for relatives diagnosed with POD. Therefore, identifying strategies to prevent POD in patients undergoing cardiac surgery represents an optimal approach that can improve patient outcomes and reduce overall healthcare costs [7].
Dexmedetomidine is a novel and highly selective α-2 adrenoceptor agonist, which has shown certain potential in the prevention and treatment of POD following cardiac surgery [8]. It has the capacity to inhibit sympathetic nervous system activity, block pain signal transduction, and produce sedation and analgesia. These effects facilitate a reduction in the use of postoperative analgesic drugs, optimize sleep quality, and theoretically decrease the overall likelihood of developing POD [9]. Dexmedetomidine has also been demonstrated to display anti-inflammatory properties by modulating the release of glutamate, reducing the toxicity of anesthetic drugs, suppressing the production of inflammatory cytokines, and regulating neuroplasticity, thereby alleviating neuroinflammation, restoring neurotransmitter balance, and relieving stress responses related to the onset of POD [10].
Despite the theoretical benefits, the efficacy of dexmedetomidine in preventing POD following cardiac surgery is still controversial. A meta-analysis in 2022 included 19 randomized controlled trials (RCTs) and showed that dexmedetomidine was not associated with a decreased incidence of POD after excluding trials at high risk of bias [11]. A meta-analysis in 2023 found that prophylactic dexmedetomidine did not decrease the incidence of POD, but significantly reduced the duration of mechanical ventilation, length of ICU stay, and length of hospital stay [12]. The meta-analysis in 2024, which included only 16 RCTs, indicated potential advantages for adult patients undergoing cardiac surgery with cardiopulmonary bypass; however, it also highlighted considerable heterogeneity [13]. The latest meta-analysis only included 7 RCTs published between 1 January 2014 and 10 March 2024 and suggested that dexmedetomidine may reduce the incidence of POD [14].
Although these meta-analyses have investigated the effect of dexmedetomidine on POD, none have comprehensively included all relevant RCTs. The conclusions are notably inconsistent, and the heterogeneity among the included studies was moderate to high. Furthermore, none of these meta-analyses conducted trial sequential analysis (TSA) to assess the conclusiveness of the evidence. Given the publication of new RCTs on this topic, we conducted a systematic review and meta-analysis with TSA to evaluate whether dexmedetomidine could prevent POD in patients undergoing cardiac surgery, aiming to provide more precise strategies for clinical practice.
Methods
Protocol and registration
This systematic review and meta-analysis with TSA adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement checklist [15], and was registered with INPLASY (INPLASY2024110008).
Search strategy
PubMed, CENTRAL, and Embase were searched for relevant RCTs about the effect of dexmedetomidine on POD in patients undergoing cardiac surgery from inception to 1 November 2024. Additional records were identified from the reference sections of previous systematic reviews and eligible studies. The following terms were used in search strategies: (“dexmedetomidine” OR “MPV 1440” OR “precedex” OR “dexdor” OR “dexdomitor”) AND (“delirium” OR “acute brain syndrome”) AND (“random”). The detailed search strategies are shown in Additional file 1.
Eligibility criteria
Inclusion criteria were as follows. (1) Participant: patients undergoing off-pump or on-pump cardiac surgery. (2) Intervention: Intravenous dexmedetomidine. (3) Comparator: placebo or positive control. The nature of positive control included, but was not limited to, propofol, midazolam, and morphine. (4) Outcome: POD. (5) Study design: RCTs published in journals, written in English or Chinese, were included.
Exclusion criteria were as follows. (1) Non-intravenous dexmedetomidine. (2) Duplicate records. (3) Studies with insufficient information or data.
Endpoints
The primary outcome of this meta-analysis was the incidence of POD, and the secondary outcome was the incidence of POAF. POD was measured using recognized assessment tools or scales, such as the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU), the Confusion Assessment Method, the Intensive Care Delirium Screening Checklist, the Richmond Agitation-Sedation Scale, the Delirium Rating Scale, and the Diagnostic and Statistical Manual, among others.
Study selection and data extraction
Two reviewers (YZ and ZR) independently performed searches of the databases and evaluated eligible articles. Any discrepancies were addressed by consulting a third reviewer (JG). The reviewers (YZ and ZR) independently extracted the following information: author, publication year, country, sample sizes, age, type of cardiac surgery, details of dexmedetomidine and control intervention, POD assessment methods, and outcome measures.
Risk of bias assessment
Two reviewers (YZ and ZR) independently utilized the Cochrane Collaboration's tool to assess the risk of bias [16]. The evaluation included aspects such as random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and other bias. These were classified as “low risk”, “high risk”, or “unclear risk”. Any discrepancies were resolved by consulting a third reviewer (JG).
Certainty of evidence assessment
Two reviewers (YZ and ZR) independently used the grading of recommendations assessment, development and evaluation (GRADE) framework to evaluate the certainty of evidence for each outcome [17]. It includes five domains: risk of bias, inconsistency, indirectness, imprecision, and other considerations. The certainty of evidence was judged as “high”, “moderate”, “low”, or “very low”. Any discrepancies were addressed by consulting a third reviewer (JG).
Statistical analysis
Risk ratio (RR) with 95% confidence interval (CI) was applied for dichotomous outcomes. Heterogeneity was evaluated through the I2 test [18]. A random-effects model was employed when the I2 value exceeded 50%. Otherwise, a fixed-effects model was utilized. Two-tailed P < 0.05 was deemed statistically significant. Subgroup analyses were conducted according to different control methods (placebo or positive control) and age of patients (older than 60 years or not). When at least ten trials were included, publication bias was assessed by the funnel plots and the Egger's test [19]. These analyses were carried out using RevMan 5.3 and R 4.4.2.
For the primary outcome, TSA was conducted using TSA 0.9.5.10 Beta to assess the risk of random errors. The required information size was ascertained in accordance with a type I error of 5% (two-tailed), a type II error of 20% (power of 80%), a control event proportion, and a 20% relative risk reduction. The conventional boundary, the trial sequential monitoring boundary, and the futility boundary were established. A cumulative Z-curve was constructed to appraise the conclusiveness of the evidence [20].
Results
Study selection
A total of 1968 records were sourced from PubMed (n = 459), CENTRAL (n = 673) and Embase (n = 836). One additional record was identified from previous systematic reviews. After removing duplicates, the number decreased to 1172. Subsequently, 1125 records were excluded based on title and abstract screening. The remaining 47 reports were retrieved for eligibility assessment. Upon full-text review, 15 reports were excluded because of ineligible outcome (n = 6), not RCT (n = 1), ineligible patients (n = 7), and duplication (n = 1). These excluded reports are listed in Additional file 2. Finally, 32 studies were included [21–52]. A flow diagram of study selection is presented in Fig. 1.
Fig. 1.
Flow diagram of the study selection process
Study characteristics
The characteristics of the included studies are summarized in Additional file 3. A total of 32 studies involving 6046 participants were included, with 3009 in the dexmedetomidine groups and 3037 in the control groups. These studies were published between 2005 and 2024 and conducted in China [26, 30, 40, 46–48, 52], the USA [28, 29, 33, 37, 38, 43], India [21, 27, 42], Korea [34, 45, 51], and so on. All studies were published in English. The number of cases included in each study ranged from 12 to 794. Twelve studies only included elderly patients who were 60 years old or older [23, 31–33, 35–39, 46, 47, 50], and the remaining studies included normal age patients [21, 22, 24–30, 34, 40–45, 48, 49, 51, 52]. The types of surgery included cardiac valve surgery in four studies [22, 28, 40, 52], coronary artery bypass grafting (CABG) in six studies [26, 29, 36, 41, 44, 46], aortic surgery in one study [45], thoracic aortic surgery in one study [51], and mixed cardiac surgery in twenty studies [21, 23–25, 27, 30–35, 37–39, 42, 43, 47–50]. Regarding the POD assessment tools, CAM-ICU was the most commonly used [22, 24, 26, 30–36, 39–41, 43, 45, 47–50]. All studies reported the incidence of POD [21–52], and 13 studies reported the incidence of POAF [24, 26, 29–31, 33–35, 38, 43, 44, 48, 51].
The dosages and administration duration of dexmedetomidine demonstrated significant variability. Fourteen studies applied a loading dose of dexmedetomidine ranging from 0.4 to 1 µg/kg [21, 22, 27–29, 31, 33, 34, 40, 41, 46, 47, 51, 52], one study used a short nighttime dose (1 μg/kg over 40 min) [38], while the remainder only administered the drug as a continuous infusion [23–26, 30, 32, 35–37, 39, 42–45, 48–50]. More than half of the studies employed postoperative dexmedetomidine intervention [23, 24, 26, 28, 30–39, 41, 42, 44, 48, 50]. Seventeen studies adopted positive control interventions [21–37], such as propofol, midazolam, morphine, remifentanil, and clonidine. Fifteen studies used normal saline as the placebo control option [38–52].
Risk of bias
The risk of bias assessment is shown in Fig. 2 and Additional file 4. Among the 32 included studies, 16 of them were categorized as being at low risk of bias [23, 26, 32, 35, 36, 38–41, 43, 45, 47–51], 11 as being at unclear risk of bias [21, 22, 25, 27, 29, 34, 37, 42, 44, 46, 52], and 5 as being at high risk of bias [24, 28, 30, 31, 33]. Random sequence generation was mentioned in 29 studies [22–24, 26–33, 35–52], and allocation concealment was emphasized in 22 studies [23, 26, 27, 29, 31–33, 35–41, 43–45, 47–51]. Five studies failed to implement blinding techniques on participants and personnel [24, 28, 30, 31, 33]. Twenty-two studies clearly described the blinding of outcome assessments [22, 23, 25, 26, 28, 31–33, 35, 36, 38–41, 43–45, 47–51]. The detailed reasons for case dropout or withdrawal were reported in the vast majority of included studies [21–43, 45–52]. Twenty-three studies were conducted according to protocols [22–24, 26, 28–33, 35, 36, 38–41, 43, 45, 47–51].
Fig. 2.
Risk of bias summary
Primary outcome: the incidence of POD
All the included RCTs presented the incidence of POD. The overall incidence of POD in the dexmedetomidine groups and the control groups was respectively 10.8% (324/3009) and 16.3% (496/3037). The meta-analysis indicated that dexmedetomidine notably reduced the incidence of POD (n = 6046; RR = 0.67, 95%CI = 0.59 to 0.76, P < 0.00001, Fig. 3), with low heterogeneity (I2 = 42%, P = 0.007). TSA showed that the cumulative Z-curve crossed both the conventional boundary and the trial sequential monitoring boundary, and did not reach the required information size (Fig. 4). The finding suggests that no further trials are necessary, and a conclusive result has been attained in advance.
Fig. 3.
Forest plot of the incidence of POD
Fig. 4.
Trial sequential analysis for the incidence of POD
Subgroup analyses based on different control methods (Additional file 5) and age of patients (Additional file 6) were conducted. As illustrated in Additional file 5, dexmedetomidine was found to be more effective in preventing POD compared with both positive control (RR = 0.47, 95% CI 0.38–0.59, P < 0.00001) and placebo control (RR = 0.83, 95% CI 0.70–0.98, P = 0.02). Additional file 6 demonstrated that dexmedetomidine decreased the incidence of POD not only in elderly patients (RR = 0.66, 95% CI 0.54–0.81, P < 0.0001), but also in normal age patients (RR = 0.68, 95% CI 0.57–0.80, P < 0.00001).
By employing a post-hoc sensitivity analysis derived from the previous meta-analysis [11], we excluded 5 studies judged to be at high risk of bias [24, 28, 30, 31, 33], and discovered that dexmedetomidine was still associated with a decreased incidence of POD (n = 5419; RR = 0.72, 95% CI 0.62–0.82, P < 0.00001, Additional file 7, with low heterogeneity (I2 = 41%, P = 0.01). This suggests that our meta-analysis results are more robust than the previous findings [11].
Secondary outcome: the incidence of POAF
A total of 13 studies provided data on the incidence of POAF [24, 26, 29–31, 33–35, 38, 43, 44, 48, 51]. The overall incidence of POAF was 25.4% (382/1501) in the dexmedetomidine groups and 31.4% (471/1498) in the control groups. The meta-analysis indicated that dexmedetomidine significantly decreased the incidence of POAF (n = 2999; RR = 0.82, 95% CI 0.74–0.92, P = 0.0005, Fig. 5), with low heterogeneity (I2 = 29%, P = 0.16).
Fig. 5.
Forest plot of the incidence of POAF
Certainty of evidence
The certainty of evidence for the incidence of POD was low due to a serious risk of bias and publication bias, and the certainty of evidence for the incidence of POAF was moderate due to a serious risk of bias (Additional file 8).
Publication bias
Because the funnel plot of the incidence of POD was asymmetric (Additional file 9) and the Egger's test affirmed the presence of publication bias (P < 0.0001), the trim-and-fill method was applied. After adding 13 dummy studies, the corrected result was RR = 0.76, 95% CI 0.62–0.93, P = 0.0076. The results before and after trim-and-fill were not reversed, indicating stability.
The funnel plot of the incidence of POAF was visually asymmetric (Additional file 10), and the Egger's test excluded the possibility of publication bias (P = 0.0503). According to the trim-and-fill method, 4 dummy studies were added, and the corrected results was RR = 0.88, 95% CI 0.79–0.98, P = 0.0246. The results before and after trim-and-fill were basically consistent.
Discussion
This meta-analysis incorporated the currently available evidence and demonstrated that dexmedetomidine was capable of lowering the incidence of POD and POAF in patients undergoing cardiac surgery. TSA confirmed the conclusiveness of the evidence regarding the role of dexmedetomidine in preventing POD. Subgroup analyses suggested that dexmedetomidine was more effective in preventing POD when compared with both positive and placebo control, and it reduced the incidence of POD not only in elderly patients but also in normal age patients.
In addition to analyzing the incidence of POD, we also conducted a meta-analysis on the incidence of POAF, which was a predictor of POD after cardiac surgery. It was confirmed that patients with POAF had a significantly higher risk of developing POD than those without POAF [53]. POAF may give rise to a reduction in cardiac output and inadequate circulation, thereby causing insufficient perfusion of tissues and organs. Additionally, the blood clots resulting from POAF can detach and occlude the blood vessels in the brain, further leading to the deprivation of oxygen in the brain tissue. Insufficient cerebral blood flow can affect cerebral oxidative metabolism and subsequently induce POD [54]. Therefore, a meta-analysis was performed to explore the effect of dexmedetomidine on the incidence of POAF, aiming to offer a more comprehensive and in-depth understanding of its preventive role in POD.
Although a low level of heterogeneity was reported in the analysis of the incidence of POD and POAF, we critically evaluated potential sources of heterogeneity that may affect the generalizability of our findings. Differences in surgical categories may lead to heterogeneity. More invasive procedures are typically associated with prolonged cardiopulmonary bypass times and exacerbated neuroinflammatory responses, which may influence the neuroprotective effects of dexmedetomidine. Dexmedetomidine dosing exhibited significant variability across studies. Higher doses may increase the risk of hypotension-induced cerebral hypoperfusion, which may counteract its neuroprotective effects. The timing of dexmedetomidine initiation may affect its efficacy in mitigating early neuroinflammatory cascades. Administering the drug in advance may help to alleviate the stress response more effectively, while delaying the administration may result in missing the critical treatment opportunity. Heterogeneity among delirium assessment tools introduces significant variability, as these tools demonstrate varying degrees of sensitivity and specificity.
In this review, the majority of the included studies solely utilized continuous infusion of dexmedetomidine. In complex endovascular aortic aneurysm repair, compared with remifentanil, dexmedetomidine could provide more reliable sedation, less gas exchange modification, and a higher incidence of persistent hypotension [55]. The recent guideline pointed out that when dexmedetomidine was used intraoperatively or postoperatively to prevent POD, the expected benefits should be weighed against the most important side effects (bradycardia and hypotension) [56]. Hence, continuous infusion of dexmedetomidine without an initial loading dose may be a better choice to reduce the risk of bradycardia and hypotension. Benzodiazepines are also frequently used for the prevention of POD. Remimazolam, as a novel benzodiazepine, helps enhance hemodynamic stability and reduce the risk of respiratory depression, showing broad application prospects in cardiac surgery patients [57, 58]. However, there are no comparative studies on its efficacy compared to dexmedetomidine for the prevention of POD.
Several previous meta-analyses have reviewed the effect of dexmedetomidine on the incidence of POD in patients undergoing cardiac surgery [11–14, 59–65]. The latest meta-analysis only included 7 RCTs [14], while others included 9–20 relevant RCTs respectively [11–13, 59–65]. The conclusions exhibit notable inconsistency. Some meta-analyses concluded that dexmedetomidine might reduce the incidence of POD with moderate to high heterogeneity among the included studies [13, 59–65]. One meta-analysis including 10 RCTs with 2550 patients showed that prophylactic dexmedetomidine use did not decrease the incidence of POD [12]. A meta-analysis in 2022 including 19 RCTs with 3266 patients found that the use of dexmedetomidine was not associated with a decreased incidence of POD after excluding RCTs at high risk of bias [11].
Compared with previous meta-analyses, this is the most up-to-date systematic review and meta-analysis with TSA. We meticulously designed search strategies and stringently applied eligibility criteria. Finally, our current review included 32 RCTs with 6046 participants, representing the largest number to date. This meta-analysis demonstrated the beneficial role of dexmedetomidine in preventing POD and POAF with low heterogeneity. In light of the considerable number of RCTs incorporated, we conducted subgroup analyses based on different control methods and age of patients. The results indicated that dexmedetomidine reduced the incidence of POD in comparison with positive control, with low heterogeneity (I2 = 0%, P = 0.77), and it decreased the incidence of POD in elderly patients, with low heterogeneity (I2 = 0%, P = 0.46). After excluding 5 studies judged as high risk of bias [24, 28, 30, 31, 33], the use of dexmedetomidine was still associated with a decreased incidence of POD. This suggests that our meta-analysis results are more robust than the previous findings [11].
Strengths and limitations
This review presents the following additional strengths. The included RCTs were carried out in various countries and encompassed a more heterogeneous sample, thereby potentially minimizing selection bias and enhancing the generalizability of the findings. TSA was applied to assess the conclusiveness of evidence concerning dexmedetomidine’s role in preventing POD, and showed sufficient evidence and conclusive results. The GRADE framework was employed to evaluate the quality of evidence and assist in formulating recommendations for healthcare practices. We also analyzed the incidence of POAF, a predictor of POD after cardiac surgery, to provide a more comprehensive understanding of the role of dexmedetomidine in preventing POD. A protocol was registered in advance, reducing the potential reporting bias of this review and enhancing its credibility.
However, the review does have several limitations. Firstly, five RCTs were at a high risk of bias due to the lack of blinding techniques on participants and personnel. Secondly, the possibility of publication bias could not be eliminated, indicating that trials with negative results were less likely to be published. Thirdly, the included RCTs utilized multiple assessment tools for the definition of POD, potentially bringing in heterogeneity that could influence our results. Fourthly, the dosages and duration of dexmedetomidine varied significantly among studies, and we cannot rule out the possibility that these factors may have influenced the findings.
Implications
The findings of this review have some implications for clinical practice. Firstly, given the positive results of this meta-analysis, we cautiously recommend perioperative dexmedetomidine as a routine approach for the prevention of POD in patients undergoing cardiac surgery. Secondly, continuous infusion of dexmedetomidine might be more recommended in clinical practice. The majority of the included studies solely utilized continuous infusion of dexmedetomidine, and the loading dose of dexmedetomidine was associated with a higher risk of hypotension and bradycardia. Thirdly, expert consensus and guidelines on the prevention of POD can incorporate and update recommendations to optimize patient outcomes in accordance with the observed findings [56]. Fourthly, for cardiac surgery patients who have experienced POAF or have a history of atrial fibrillation, more attention should be paid to the prophylactic use of dexmedetomidine.
Conclusions
This systematic review suggested that dexmedetomidine could reduce the incidence of POD in patients undergoing cardiac surgery and was associated with a decreased incidence of POAF. The findings should be interpreted with caution because of the low to moderate quality of evidence. Further trials are still needed to explore the optimal regimen of dexmedetomidine.
Supplementary Information
Below is the link to the electronic supplementary material.
Additional file 1. The detailed search strategies
Additional file 2. Reports excluded by checking the full text
Additional file 3. Characteristics of the included studies
Additional file 5. Subgroup analysis of the incidence of POD based on different control methods
Additional file 6. Subgroup analysis of the incidence of POD based on different age of patients
Additional file 7. Forest plot of the incidence of POD after excluding 5 studies judged as high risk of bias
Additional file 8. GRADE evidence profiles
Additional file 9. Funnel plot of the incidence of POD
Additional file 10. Funnel plot of the incidence of POAF
Acknowledgements
Not applicable.
Abbreviations
- POD
Postoperative delirium
- RCTs
Randomized controlled trials
- POAF
Postoperative atrial fibrillation
- RR
Risk ratio
- CI
Confidence interval
- TSA
Trial sequential analysis
- PRISMA
Preferred reporting items for systematic reviews and meta-analyses
- GRADE
Grading of recommendations assessment, development and evaluation
- CABG
Coronary artery bypass grafting
- CAM-ICU
Confusion assessment method for the intensive care unit
Author contributions
YZ and ZR searched the database, assessed eligible articles, extracted necessary information, evaluated the risk of bias and the certainty of evidence, and wrote the original draft. JG and XH performed statistical analysis. QL reviewed and revised the manuscript. All authors read and approved the final manuscript.
Funding
This work was supported by Sichuan Science and Technology Program (No. 2023ZYD0168).
Availability of data and materials
Data is provided within the manuscript or supplementary information files.
Declarations
Ethics approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Additional file 1. The detailed search strategies
Additional file 2. Reports excluded by checking the full text
Additional file 3. Characteristics of the included studies
Additional file 5. Subgroup analysis of the incidence of POD based on different control methods
Additional file 6. Subgroup analysis of the incidence of POD based on different age of patients
Additional file 7. Forest plot of the incidence of POD after excluding 5 studies judged as high risk of bias
Additional file 8. GRADE evidence profiles
Additional file 9. Funnel plot of the incidence of POD
Additional file 10. Funnel plot of the incidence of POAF
Data Availability Statement
Data is provided within the manuscript or supplementary information files.