Value of variation of end-tidal carbon dioxide for predicting fluid responsiveness during the passive leg raising test in patients with mechanical ventilation: a systematic review and meta-analysis

Background The ability of end-tidal carbon dioxide (ΔEtCO2) for predicting fluid responsiveness has been extensively studied with conflicting results. This meta-analysis aimed to explore the value of ΔEtCO2 for predicting fluid responsiveness during the passive leg raising (PLR) test in patients with mechanical ventilation. Methods PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched up to November 2021. The diagnostic odds ratio (DOR), sensitivity, and specificity were calculated. The summary receiver operating characteristic curve was estimated, and the area under the curve (AUROC) was calculated. Q test and I2 statistics were used for study heterogeneity and publication bias was assessed by Deeks’ funnel plot asymmetry test. We performed meta-regression analysis for heterogeneity exploration and sensitivity analysis for the publication bias. Results Overall, six studies including 298 patients were included in this review, of whom 149 (50%) were fluid responsive. The cutoff values of ΔEtCO2 in four studies was 5%, one was 5.8% and the other one was an absolute increase 2 mmHg. Heterogeneity between studies was assessed with an overall Q = 4.098, I2 = 51%, and P = 0.064. The pooled sensitivity and specificity for the overall population were 0.79 (95% CI 0.72–0.85) and 0.90 (95% CI 0.77–0.96), respectively. The DOR was 35 (95% CI 12–107). The pooled AUROC was 0.81 (95% CI 0.77–0.84). On meta-regression analysis, the number of patients was sources of heterogeneity. The sensitivity analysis showed that the pooled DOR ranged from 21 to 140 and the pooled AUC ranged from 0.92 to 0.96 when one study was omitted. Conclusions Though the limited number of studies included and study heterogeneity, our meta-analysis confirmed that the ΔEtCO2 performed moderately in predicting fluid responsiveness during the PLR test in patients with mechanical ventilation.

Prevalence of Anxiety in University Students during the COVID-19 Pandemic: A Systematic Review

There is a dearth of evidence synthesis on the prevalence of anxiety among university students even though the risk of psychological disorders among this population is quite high. We conducted a quantitative systematic review to estimate the global prevalence of anxiety among university students during the COVID-19 pandemic. A systematic search for cross-sectional studies on PubMed, Scopus, and PsycINFO, using PRISMA guidelines, was conducted from September 2020 to February 2021. A total of 36 studies were included, using a random-effects model to calculate the pooled proportion of anxiety. A meta-analysis of the prevalence estimate of anxiety yielded a summary prevalence of 41% (95% CI = 0.34–0.49), with statistically significant evidence of between-study heterogeneity (Q = 80801.97, I2 = 100%, p ≤ 0.0001). A subgroup analysis reported anxiety prevalence in Asia as 33% (95% CI:0.25–0.43), the prevalence of anxiety in Europe as 51% (95% CI: 0.44–0.59), and the highest prevalence of anxiety in the USA as 56% (95% CI: 0.44–0.67). A subgroup gender-based analysis reported the prevalence of anxiety in females as 43% (95% CI:0.29–0.58) compared to males with an anxiety prevalence of 39% (95% CI:0.29–0.50). University students seem to have a high prevalence of anxiety, indicating an increased mental health burden during this pandemic.

More focal, less heterogeneous? Multi-level Meta-Analysis of Cathodal High-Definition Transcranial Direct Current Stimulation Effects on Language and Cognition

High-definition transcranial direct current stimulation (HD-tDCS) is a relatively focal, novel non-invasive brain stimulation method with the potential to investigate causal contribution of specific cortical brain regions to language and cognition. Studies with HD-tDCS typically employ a 4×1 electrode design with a single central target electrode surrounded by four return electrodes, among which return current intensity is evenly distributed. With cathodal HD-tDCS, neural excitability in the target region is assumed to be reduced, which offers interesting perspectives for psychological research and interventions. This multi-level meta-analysis compiles published studies using cathodal HD-tDCS in 4×1 configuration to modulate cognition and behavior. In total, 11 eligible reports were included with 2-15 effect sizes within each study, yielding 77 effect sizes in total. We observed no significant overall effect and no moderation by within-study and between-study variables. However, studies varied tremendously in task parameters, outcomes, and even technical parameters. Interestingly, within-study heterogeneity exceeded between-study heterogeneity in the present sample, and moderators hardly reduced the residual heterogeneity. Across domains and configurations, both positive and negative effect sizes are possible. We discuss the findings in relation to conventional cathodal tDCS and the framework of polarity specificity. Fundamental aspects of cathodal HD-tDCS are still to be addressed in future research.

Impact of Circadian Desynchrony on Spermatogenesis: A Mini Review

The purpose of this mini review is to provide data about pre-clinical and clinical evidence exploring the impact of circadian desynchrony on spermatogenesis. Several lines of evidence exist demonstrating that disruption of circadian rhythms may interfere with male fertility. Experimental knock-out or knock-down of clock genes, physiologically involved in the regulation of circadian rhythms, are associated with impairments of fertility pathways in both animal and human models. Moreover, disruption of circadian rhythms, due to reduction of sleep duration and/or alteration of its architecture can negatively interfere in humans with circulating levels of male sexual hormones as well as with semen parameters. Unfortunately, current evidence remains low due to study heterogeneity.

Association Between Prediabetes and Retinopathy: A Meta-Analysis

Diabetes confers an increased risk of microvascular complications, including retinopathy. However, whether prediabetes is also related to retinopathy has not been comprehensively examined. We performed a meta-analysis to evaluate the relationship between prediabetes and retinopathy. This meta-analysis included relevant observational studies from Medline, Embase, and Web of Science databases. A random-effect model after incorporation of the intra-study heterogeneity was selected to pool the results. Subgroup analyses were applied to evaluate the influences of study characteristics on relationship. Nine cross-sectional studies including 14 751 community dwelling adult participants were included; 3847 (26.1%) of them were prediabetic. Results showed that prediabetes was associated with a higher prevalence of retinopathy compared to normoglycemia [odds ratio (OR): 1.55, 95% confidence interval (CI): 1.10–2.20, p=0.01, I2=34%]. Sensitivity analysis by excluding one study at a time showed consistent result (OR: 1.35 to 1.73, p all<0.05). Subgroup analysis showed study characteristics such as definition of prediabetes, country of study, sample size, mean age of participants, or univariate or multivariate analyses may not significantly affect the association (p for subgroup difference all>0.05). Current evidence suggests that patients with prediabetes may be associated with higher prevalence of retinopathy as compared to those with normoglycemia. Although prospective cohort studies are needed to validate these findings, results of our meta-analysis highlighted the importance of early prevention of retinopathy in patients with prediabetes.

Pre-Statistical Harmonization of Behavioral Instruments Across Eight Surveys and Trials

Data harmonization methods facilitate further use of existing studies and research resources. Most statistical harmonization methods require pooling data across studies, which is complex and requires careful scrutiny of source data. Most methods (e.g., item response theory) require datasets to have common items for linking a common construct across studies: this necessitates the qualitative process of pre-statistical harmonization. Here, we document pre-statistical harmonization of items measuring behavioral and psychological symptoms (e.g., agitation, wandering, etc.) which represent problematic behaviors among people with dementia administered in a national survey (ADAMS), evaluations conducted at Alzheimer’s Disease Research Centers (NACC), and in six randomized trials (COPE, TAP, ALZQOL, ACT, REACH, ADSPlus). We describe our approach to review question content and scoring procedures to establish comparability across items prior to data pooling. We identified 327 items from 15 instruments across these eight studies. We found considerable cross-study heterogeneity in administration and coding procedures for items that measure the same domain. For example, eight items were coded as count variables in some studies but as categorical variables in others. Moreover, of the 359 items, 191 are conditionally dependent on values of another item. These issues around item response heterogeneity and conditional dependency needed to be resolved prior to estimation of item response theory models for statistical co-calibration. We leveraged several rigorous data transformation procedures to address these issues, including re-coding and winsorization. This study provides guidelines for how future research may acknowledge and address similar issues in pooling behavioral and related instruments.

Distinctive prosodic features of people with autism spectrum disorder: a systematic review and meta-analysis study

In this systematic review, we analyzed and evaluated the findings of studies on prosodic features of vocal productions of people with autism spectrum disorder (ASD) in order to recognize the statistically significant, most confirmed and reliable prosodic differences distinguishing people with ASD from typically developing individuals. Using suitable keywords, three major databases including Web of Science, PubMed and Scopus, were searched. The results for prosodic features such as mean pitch, pitch range and variability, speech rate, intensity and voice duration were extracted from eligible studies. The pooled standard mean difference between ASD and control groups was extracted or calculated. Using I2 statistic and Cochrane Q-test, between-study heterogeneity was evaluated. Furthermore, publication bias was assessed using funnel plot and its significance was evaluated using Egger’s and Begg’s tests. Thirty-nine eligible studies were retrieved (including 910 and 850 participants for ASD and control groups, respectively). This systematic review and meta-analysis showed that ASD group members had a significantly larger mean pitch (SMD = − 0.4, 95% CI [− 0.70, − 0.10]), larger pitch range (SMD = − 0.78, 95% CI [− 1.34, − 0.21]), longer voice duration (SMD = − 0.43, 95% CI [− 0.72, − 0.15]), and larger pitch variability (SMD = − 0.46, 95% CI [− 0.84, − 0.08]), compared with typically developing control group. However, no significant differences in pitch standard deviation, voice intensity and speech rate were found between groups. Chronological age of participants and voice elicitation tasks were two sources of between-study heterogeneity. Furthermore, no publication bias was observed during analyses (p > 0.05). Mean pitch, pitch range, pitch variability and voice duration were recognized as the prosodic features reliably distinguishing people with ASD from TD individuals.

Transmission Routes of Antibiotic Resistant Bacteria: A Systematic Review

BackgroundQuantification of acquisition routes of antibiotic resistant bacteria (ARB) is pivotal for understanding transmission dynamics and designing cost-effective interventions. Different methods have been used to quantify the importance of transmission routes, such as relative risks, odds ratios (OR), genomic comparisons and basic reproduction numbers. We systematically reviewed reported estimates on acquisition routes’ contributions of ARB in humans, animals, water and the environment and assessed the methods used to quantify the importance of transmission routes.MethodsPubMed and EMBASE were searched, resulting in 6054 articles published up until January 1st, 2019. Full text screening was performed on 525 articles and 277 are included.ResultsWe extracted 718 estimates with S. aureus (n=273), E. coli (n=157) and Enterobacteriaceae (n=99) being studied most frequently. Most estimates were derived from statistical methods (n=560), mainly expressed as risks (n=246) and ORs (n=239), followed by genetic comparisons (n=85), modelling (n=62) and dosage of ARB ingested (n=17). Transmission routes analysed most frequently were occupational exposure (n=157), travelling (n=110) and contacts with carriers (n=83). Studies were mostly performed in the United States (n=142), the Netherlands (n=87) and Germany (n=60). Comparison of methods was not possible as studies using different methods to estimate the same route were lacking. Due to study heterogeneity not all estimates by the same method could be pooled.ConclusionDespite an abundance of published data the relative importance of transmission routes of ARB has not been accurately quantified. Links between exposure and acquisition are often present, but the frequency of exposure is missing, which disables estimation of transmission routes’ importance. To create effective policies reducing ARB, estimates of transmission should be weighed by the frequency of exposure occurrence.

Pulmonary valve tissue engineering strategies in large animal models

In the last 25 years, numerous tissue engineered heart valve (TEHV) strategies have been studied in large animal models. To evaluate, qualify and summarize all available publications, we conducted a systematic review and meta-analysis. We identified 80 reports that studied TEHVs of synthetic or natural scaffolds in pulmonary position (n = 693 animals). We identified substantial heterogeneity in study designs, methods and outcomes. Most importantly, the quality assessment showed poor reporting in randomization and blinding strategies. Meta-analysis showed no differences in mortality and rate of valve regurgitation between different scaffolds or strategies. However, it revealed a higher transvalvular pressure gradient in synthetic scaffolds (11.6 mmHg; 95% CI, [7.31–15.89]) compared to natural scaffolds (4,67 mmHg; 95% CI, [3,94–5.39]; p = 0.003). These results should be interpreted with caution due to lack of a standardized control group, substantial study heterogeneity, and relatively low number of comparable studies in subgroup analyses. Based on this review, the most adequate scaffold model is still undefined. This review endorses that, to move the TEHV field forward and enable reliable comparisons, it is essential to define standardized methods and ways of reporting. This would greatly enhance the value of individual large animal studies.

Systematic review and meta-analyses of studies analysing instructions to authors from 1987 to 2017

To gain insight into changes of scholarly journals’ recommendations, we conducted a systematic review of studies that analysed journals’ Instructions to Authors (ItAs). We summarised results of 153 studies, and meta-analysed how often ItAs addressed: 1) authorship, 2) conflicts of interest, 3) data sharing, 4) ethics approval, 5) funding disclosure, and 6) International Committee of Medical Journal Editors’ Uniform Requirements for Manuscripts. For each topic we found large between-study heterogeneity. Here, we show six factors that explained most of that heterogeneity: 1) time (addressing of topics generally increased over time), 2) country (large differences found between countries), 3) database indexation (large differences found between databases), 4) impact factor (topics were more often addressed in highest than in lowest impact factor journals), 5) discipline (topics were more often addressed in Health Sciences than in other disciplines), and 6) sub-discipline (topics were more often addressed in general than in sub-disciplinary journals).