Systematic Review and Meta-analysis: Sometimes Bigger Is Indeed Better

CAR, mGPS and hs-mGPS: What is among them the best gero-biomarker for age-related diseases? And for what clinical application?

The identification of biomarkers linked to the onset, progression, and prevention of age-related diseases (ARD), in the era of personalized medicine, represents the best goal of geroscience. Geroscience has the fundamental role of exploring and identifying the biological mechanisms of aging to suggest interventions capable of stopping/delaying the many pathological conditions and disabilities related to age. Therefore, it has become its key priority, as well as that of clinical practice and research, based on identifying and validating a range of biomarkers, geromarkers, which can be used to diagnostic, prognostic, or predictive clinical purposes. Indeed, geromarkers have, the potential to predict ARD trajectories and facilitate targeted interventions to slow down the related disabilities. Here our attention is paid to the inflammatory indexes (CAR, mGPS, hs-mGPS) linked to the relationship between the plasma levels of two inflammatory analytes, the typical positive protein of the acute phase, and the negative one, i.e. c-reactive protein (CRP) and albumin, respectively. These indexes allow us to understand the magnitude of the two main mechanisms predicted to influence the aging process, including inflammation and immunosenescence, as well as the degree of ARD severity. Evidence on their relationship with ARD is widely reported and discussed, to understand which can represent the best ARD geromarker, and its clinical application.

The effect of general anesthesia and conscious sedation in endovascular thrombectomy for acute ischemic stroke: an updated meta-analysis of randomized controlled trials and trial sequential analysis

Objectives

General anesthesia (GA) and conscious sedation (CS) are common methods for endovascular thrombectomy (EVT) in acute ischemic stroke (AIS). However, the risks and benefits of each strategy are unclear. This study aimed to summarize the latest RCTs and compare the postoperative effects of the two methods on EVT patients.

Materials and methods

We systematically searched the database for GA and CS in AIS patients during EVT. The retrieval time was from the creation of the database until March 2023. The quality of the studies was evaluated using the Cochrane risk of bias tool. Random-effects or fixed-effects meta-analyses were used to assess all outcomes.

Results

We preliminarily identified 304 studies, of which 8 were included. Based on the pooled estimates, there were no significant differences between the GA group and the CS group in terms of good functional outcomes (mRS0-2) and mortality rate at 3 months (RR = 1.09, 95% CI: 0.95-1.24, p = 0.23) (RR = 0.95, 95% CI: 0.75-1.22, p = 0.70) as well as in NHISS at 24 h after treatment (SMD = -0.01, 95% CI: -0.13 to 0.11, p = 0.89). However, the GA group had better outcomes in terms of achieving successful recanalization of the blood vessel (RR = 1.13, 95% CI: 1.07-1.19, p < 0.0001). The RR value for the risk of hypotension was 1.87 (95% CI: 1.42-2.47, p < 0.00001); for pneumonia, RR was 1.43 (95% CI: 1.07-1.90, p = 0.01); and for symptomatic intracerebral hemorrhage, RR was 0.94 (95% CI: 0.74-1.26, p = 0.68). The pooled RR value for complications after intervention was 1.03 (95% CI, 0.87-1.22, p = 0.76).

Conclusion

In patients undergoing EVT for AIS, GA, and CS are associated with similar rates of functional independence. Further trials of a larger scale are needed to confirm these findings.

Neuropharmacological efficacy of metformin for stroke in rodents: A meta-analysis of preclinical trials

Background: Stroke, including ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage (SAH), remains a leading cause of mortality globally. Different stroke subtypes have similar detrimental effects in multiple fields of health. Previous research has shown that metformin plays a neuroprotective role in experimental animal models of stroke; however, a preclinical quantitative analysis on the ability of metformin to treat stroke is still lacking. This meta-analysis evaluates the efficacy of metformin in improving stroke prognosis in rodent models of stroke. Methods: Relevant preclinical trials were retrieved from PubMed, EMBASE, and the Web of Science. The neurological score (NS), brain water content (BWC), infarct size, rotarod test, TUNEL, neuron quantity, microglia quantity, and p-AMPK levels were compared between a control group and a metformin group using the standardized mean difference (SMD) and corresponding confidence interval (CI). Quality was assessed with SYRCLE's risk of bias tool. Results: Fifteen articles published from 2010 to 2022 were included in the meta-analysis. The metformin group had statistically significant differences compared to the control group in the following aspects: NS (SMD -1.45; 95% CI -2.32, -0.58; p = 0.001), BWC (SMD -3.22; 95% CI -4.69, -1.76; p < 0.0001), infarct size (SMD -2.90; 95% CI -3.95, -1.85; p < 0.00001), rotarod test (SMD 2.55; 95% CI 1.87, 3.23; p < 0.00001), TUNEL (SMD -3.63; 95% CI -5.77, -1.48; p = 0.0009), neuron quantity (SMD 3.42; 95% CI 2.51, 4.34; p < 0.00001), microglia quantity (SMD -3.06; 95% CI -4.69, -1.44; p = 0.0002), and p-AMPK levels (SMD 2.92; 95% CI 2.02, 3.82; p < 0.00001). Furthermore, sensitivity analysis and stratified analysis were conducted for heterogeneous outcome indicators. Conclusion: Overall, metformin treatment improves severe outcomes triggered by stroke. Despite the limitations intrinsic to animal studies, this systematic review may provide a vital reference for future high-quality preclinical trials and clinical use.

The therapeutic efficacy of resveratrol for acute lung injury—A meta−analysis of preclinical trials

Background: Resveratrol (RES) has a protective effect on acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Our purpose was to conduct a meta−analysis to investigate the efficacy of RES for ALI/ARDS in animal models.

Methods: PubMed, EMBASE and Web of Science were searched to screen relevant preclinical trials. The standardized mean difference (SMD) was used to compare the lung injury score, lung wet−dry weight ratio (W/D ratio), tumor necrosis factor−α (TNF−α), interleukin−1β (IL−1β), IL−6, IL−10, the number of neutrophils in bronchoalveolar lavage fluid (BALF) and the total protein in BALF between the treatment and control groups. SYRCLE’s risk of bias tool was used for quality assessment.

Results: A total of 17 studies published from 2005 to 2021 were included in our study to calculate the SMD with corresponding confidence interval (CI). As compared with controls, RES significantly decreased the lung injury score (SMD −2.06; 95% CI −2.77, −1.35; p < 0.00001) and W/D ratio (SMD −1.92; 95% CI −2.62, −1.22; p < 0.00001). RES also reduced the number of neutrophils in BALF (SMD −3.03; 95% CI −3.83, −2.24; p < 0.00001) and the total protein in BALF (SMD −5.59; 95% CI −10.10, −1.08; p = 0.02). Furthermore, RES was found to downregulate proinflammatory mediators such as TNF−α (SMD −2.02; 95% CI −3.09, −0.95; p = 0.0002), IL−1β (SMD −2.51; 95% CI −4.00, −1.02; p = 0.001) and IL−6 (SMD −2.26; 95% CI −3.49, −1.04; p = 0.0003). But RES had little effect on the anti−inflammatory mediators such as IL−10 (SMD 2.80; 95% CI −0.04, 5.63; p = 0.05). Sensitivity analysis and stratified analysis were performed for the outcome indicators with heterogeneity.

Conclusion: RES treatment is effective on reducing the severity of ALI. However, more animal studies and human trials are needed for further investigation. Our study may provide a reference for preclinical and clinical studies in the future to some extent.

Systematic reviews: Not always a pain

Systematic reviews analyze the evidence surrounding a specific intervention within a population. High quality systematic reviews can help clinicians and policymakers accurately understand a treatment intervention. This article outlines the basic principles of systematic review development, including assembling a research team, defining the research question, publishing a protocol, designing and executing the search, study selection, extracting the data, assessing risk of bias, synthesizing the data and conducting a certainty assessment. In addition, we will address common pitfalls and highlight special considerations for the field of interventional pain medicine. Understanding systematic review methodology will help investigators improve their primary research and in turn, better primary literature will improve the value of high quality reviews.

Efficacy of Resveratrol in Experimental Subarachnoid Hemorrhage Animal Models: A Stratified Meta-Analysis

Background: Subarachnoid hemorrhage (SAH) is a serious neurosurgical emergency with extremely high morbidity and mortality rates. Resveratrol (RES), a natural polyphenolic phytoalexin, is broadly presented in a wide variety of plants. Previous research had reasonably revealed its neuroprotective effects on experimental SAH animal models to some extent. But the results were more controversial. Therefore, we conducted a meta-analysis to evaluate the evidence on the effectiveness of RES in improving outcomes in SAH animal models. Methods: A systematic literature review was conducted in PubMed, EMBASE, and Web of Science databases to incorporate experimental control studies on the efficacy of RES on SAH models into our research. The standardized mean difference (SMD) was used to compare the brain water content (BWC) and neurological score (NS) between the treatment and control groups. Results: Overall, 16 articles published from 2014 to 2022 met the inclusion criteria. The meta-analysis of BWC showed a significant difference in favor of RES treatment (SMD: -1.026; 95% CI: -1.380, -0.672; p = 0.000) with significant heterogeneity (Q = 84.97; I² = 60.0%; p = 0.000). Further stratified analysis was performed for methodological differences, especially dosage, time of treatments, and time-point of outcome assessment. The meta-analysis of NS showed a significant difference in favor of RES treatment (SMD: 1.342; 95% CI: 1.089, 1.595; p = 0.000) with low heterogeneity (Q = 25.58; I² = 17.9%; p = 0.223). Conclusion: Generally, RES treatment showed an improvement in both pathological and behavioral outcomes in SAH animal models. The results of this study may provide a reference for preclinical and clinical studies in the future to some extent, with great significance for human health.

Meta-analysis using Python: a hands-on tutorial

BACKGROUND

Meta-analysis is a central method for quality evidence generation. In particular, meta-analysis is gaining speedy momentum in the growing world of quantitative information. There are several software applications to process and output expected results. Open-source software applications generating such results are receiving more attention. This paper uses Python's capabilities to provide applicable instruction to perform a meta-analysis.

METHODS

We used the PythonMeta package with several modifications to perform the meta-analysis on an open-access dataset from Cochrane. The analyses were complemented by employing Python's zEpid package capable of creating forest plots. Also, we developed Python scripts for contour-enhanced funnel plots to assess funnel plots asymmetry. Finally, we ran the analyses in R and STATA to check the cross-validity of the results.

RESULTS

A stepwise instruction on installing the software and packages and performing meta-analysis was provided. We shared the Python codes for meta-analysts to follow and generate the standard outputs. Our results were similar to those yielded by R and STATA.

CONCLUSION

We successfully produced standard meta-analytic outputs using Python. This programming language has several flexibilities to improve the meta-analysis results even further.

Statistics From A (Agreement) to Z (z Score): A Guide to Interpreting Common Measures of Association, Agreement, Diagnostic Accuracy, Effect Size, Heterogeneity, and Reliability in Medical Research

Researchers reporting results of statistical analyses, as well as readers of manuscripts reporting original research, often seek guidance on how numeric results can be practically and meaningfully interpreted. With this article, we aim to provide benchmarks for cutoff or cut-point values and to suggest plain-language interpretations for a number of commonly used statistical measures of association, agreement, diagnostic accuracy, effect size, heterogeneity, and reliability in medical research. Specifically, we discuss correlation coefficients, Cronbach's alpha, I2, intraclass correlation (ICC), Cohen's and Fleiss' kappa statistics, the area under the receiver operating characteristic curve (AUROC, concordance statistic), standardized mean differences (Cohen's d, Hedge's g, Glass' delta), and z scores. We base these cutoff values on what has been previously proposed by experts in the field in peer-reviewed literature and textbooks, as well as online statistical resources. We integrate, adapt, and/or expand previous suggestions in attempts to (a) achieve a compromise between divergent recommendations, and (b) propose cutoffs that we perceive sensible for the field of anesthesia and related specialties. While our suggestions provide guidance on how the results of statistical tests are typically interpreted, this does not mean that the results can universally be interpreted as suggested here. We discuss the well-known inherent limitations of using cutoff values to categorize continuous measures. We further emphasize that cutoff values may depend on the specific clinical or scientific context. Rule-of-the thumb approaches to the interpretation of statistical measures should therefore be used judiciously.

Effects of perioperative interventions for preventing postoperative delirium: A protocol for systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Postoperative delirium (POD) not only increases the medical burden but also adversely affects patient prognosis. Although some cases of delirium can be avoided by early intervention, there is no clear evidence indicating whether any of these measures can effectively prevent POD in specific patient groups.

OBJECTIVE

The aim of this meta-analysis was to compare the efficacy and safety of the existing preventive measures for managing POD.

METHODS

The PubMed, OVID (Embase and MEDLINE), Web of Science, and the Cochrane Library databases were searched for articles published before January 2020. The relevant randomized controlled trials (RCTs) were selected based on the inclusion and exclusion criteria. Data extraction and methodological quality assessment were performed according to a predesigned data extraction form and scoring system, respectively. The interventions were compared on the basis of the primary outcome like incidence of POD, and secondary outcomes like duration of delirium and the length of intensive care unit and hospital stay.

RESULTS

Sixty-three RCTs were included in the study, covering interventions like surgery, anesthesia, analgesics, intraoperative blood glucose control, cholinesterase inhibitors, anticonvulsant drugs, antipsychotic drugs, sleep rhythmic regulation, and multi-modal nursing. The occurrence of POD was low in 4 trials that monitored the depth of anesthesia with bispectral index during the operation (P < .0001). Two studies showed that supplementary analgesia was useful for delirium prevention (P = .002). Seventeen studies showed that perioperative sedation with α2-adrenergic receptor agonists prevented POD (P = .0006). Six studies showed that both typical and atypical antipsychotic drugs can reduce the incidence of POD (P = .002). Multimodal nursing during the perioperative period effectively reduced POD in 6 studies (P < .00001). Furthermore, these preventive measures can reduce the duration of delirium, as well as the total and postoperative length of hospitalized stay for non-cardiac surgery patients. For patients undergoing cardiac surgery, effective prevention can only reduce the length of intensive care unit stay.

CONCLUSION

Measures including intraoperative monitoring of bispectral index, supplemental analgesia, α2-adrenergic receptor agonists, antipsychotic drugs, and multimodal care are helpful to prevent POD effectively. However, larger, high-quality RCTs are needed to verify these findings and develop more interventions and drugs for preventing postoperative delirium.

The efficacy of vaccination to prevent human papilloma viruses infection at anal and oral: a systematic review and meta-analysis

OBJECTIVE

The objective of this study was to review evidence on the effectiveness of vaccination in the prevention of human papilloma virus (HPV) infection at the cervix, anal, and oral.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

The key search limitations are as follows: "Human Papilloma Virus", "Papilloma Virus, Human" "Human Papillomavirus Virus", "HPV" and "oral", "anus", "anal", "penis", "cervical," and "vaccine". Randomized controlled studies were searched and analyzed the risk ratio by Review Manager 5.3; funnel plot was adopted for publication bias analysis.

RESULTS

Five randomized controlled studies enrolling 13,686 participants were retrieved, analyzed, and showed that HPV vaccination can effectively block HPV infection at cervical, anal, and oral. Subgroup analysis, moreover, proved that HPV 16/18 is more effective than HPV 6/11/16/18 in preventing anal and oral infections.

CONCLUSION

HPV vaccine is efficacious in preventing HPV infection not only at cervical but also at anal and oral, as evidence supported by relevant studies.

Efficacy of melatonin in animal models of intracerebral hemorrhage: a systematic review and meta-analysis

Melatonin is a potent antioxidant and anti-inflammatory agent that is showing promising results in acute brain injury. The aim of this study was to systematically evaluate the pre-clinical evidence on the effectiveness of melatonin in improving outcome after intracerebral hemorrhage (ICH). We searched mainstream databases from the inception to the end of June 2020. Outcomes were measured by neurobehavioral scores or brain water content. Meta-analyses were performed with Stata 12.0 and Review Manager 5.3. Finally, 8 articles published from 2008 to 2019 met the inclusion criteria. Meta-analysis of pre-clinical data revealed an overall positive effect on neurobehavioral outcome with a standardized mean difference (SMD) of -0.81 (95% CI: -1.47, -0.15; p = 0.016) with significant heterogeneity (Q = 41.49, I² = 68.7%; p = 0.000). Further subgroup analysis were performed from methodological differences, especially dose and timing of treatments. Furthermore, melatonin reduced cerebral edema by an SMD of -0.78 (95% CI: -1.23, -0.34; p = 0.001) with low heterogeneity. In conclusion, melatonin treatment significantly improves both behavioral and pathological outcomes in animal models of ICH. In addition, the results should be interpreted in light of the limitations in experimental design and methodological quality of the studies included in the meta-analysis.

Global Gender Differences in Pilonidal Sinus Disease: A Random-Effects Meta-Analysis

BACKGROUND

Pilonidal sinus disease (PSD) is traditionally associated with young male patients. While PSD is rare in Asia and Africa, lifestyles are changing considerably throughout the so-called developed world. We question that PSD is an overwhelmingly male disease and that the proportion of women suffering from PSD is worldwide evenly distributed in a homogenous matter.

METHODS

We analysed the world literature published between 1833 and 2018, expanding on the database created by Stauffer et al. Following correction for gender bias with elimination of men-only and women-only studies, data were processed using random-effects meta-analysis in the technique of DerSimonian and Laird.

RESULTS

The share of female pilonidal sinus disease patients analysed from all studies available in the world literature is 21%. There are marked regional differences including South America (39%), North America as well as Australia/New Zealand (29%) and Asia (7%), which are highly significant. These results stand fast even if analysis without gender bias corrections was applied.

CONCLUSION

The share of female patients suffering from PSD is considerable. It is time to think of PSD as a disease of both men and women. Previously unknown, there are significant regional differences worldwide; the reason(s) for the regional differences is still unclear.

Melatonin and its analogues for the prevention of postoperative delirium: A systematic review and meta-analysis

It remains unclear whether melatonin and its analogues prevent postoperative delirium (POD). Therefore, we conducted a systematic review and meta-analysis to evaluate the effect of melatonin and its analogues on POD prevention. PubMed, Cochrane Library, Web of Science, Embase and CINAHL databases were searched. Primary outcome was the incidence of POD. Six randomized controlled trials, 2 cohort studies and 1 case-control study were included in this meta-analysis. Results showed that melatonin and its analogue ramelteon decreased the incidence of POD in the entire adult surgical population (odds ratio [OR] = 0.45, 95% confidence interval [CI] 0.24-0.84, P = .01). When administered at a higher dose (5 mg), melatonin was effective in reducing the POD incidence (OR = 0.32, 95% CI 0.20-0.52, P < .00001). Melatonin administered less than 5 elimination half-lives before the surgery significantly reduced the POD incidence (OR = 0.31, 95% CI 0.19-0.49, P < .00001). Current literature supports the effectiveness of melatonin and its analogue ramelteon in POD prevention. However, the present study was limited by the significant heterogeneity of the included studies. More studies are needed to ascertain the preventive effect of melatonin and its analogues on the incidence of delirium after cardiac and noncardiac surgeries.