scholarly journals Estimation in meta-analyses of response ratios

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Ilyas Bakbergenuly ◽  
David C. Hoaglin ◽  
Elena Kulinskaya
Keyword(s):  
Meta Analysis ◽  
Weighted Average ◽  
Effective Sample Size ◽  
Logarithmic Scale ◽  
Response Ratio ◽  
Effect Measure ◽  
Interval Estimators ◽  
Point Estimators ◽  
Meta Analyses ◽  
And Control

Abstract Background For outcomes that studies report as the means in the treatment and control groups, some medical applications and nearly half of meta-analyses in ecology express the effect as the ratio of means (RoM), also called the response ratio (RR), analyzed in the logarithmic scale as the log-response-ratio, LRR. Methods In random-effects meta-analysis of LRR, with normal and lognormal data, we studied the performance of estimators of the between-study variance, τ2, (measured by bias and coverage) in assessing heterogeneity of study-level effects, and also the performance of related estimators of the overall effect in the log scale, λ. We obtained additional empirical evidence from two examples. Results The results of our extensive simulations showed several challenges in using LRR as an effect measure. Point estimators of τ2 had considerable bias or were unreliable, and interval estimators of τ2 seldom had the intended 95% coverage for small to moderate-sized samples (n<40). Results for estimating λ differed between lognormal and normal data. Conclusions For lognormal data, we can recommend only SSW, a weighted average in which a study’s weight is proportional to its effective sample size, (when n≥40) and its companion interval (when n≥10). Normal data posed greater challenges. When the means were far enough from 0 (more than one standard deviation, 4 in our simulations), SSW was practically unbiased, and its companion interval was the only option.

scholarly journals Simulation study of estimating between-study variance and overall effect in meta-analyses of log-response-ratio for normal data

2020 ◽  
Author(s):  
Ilyas Bakbergenuly ◽  
David C. Hoaglin ◽  
Elena Kulinskaya
Keyword(s):  
Profile Likelihood ◽  
Meta Analysis ◽  
Response Ratio ◽  
Normal Distributions ◽  
Lognormal Distributions ◽  
Effect Measure ◽  
Log Response Ratio ◽  
Interval Estimators ◽  
Point Estimators ◽  
Meta Analyses

Methods for random-effects meta-analysis require an estimate of the between-study variance, $\tau^2$. The performance of estimators of $\tau^2$ (measured by bias and coverage) affects their usefulness in assessing heterogeneity of study-level effects, and also the performance of related estimators of the overall effect. For the effect measure log-response-ratio (LRR, also known as the logarithm of the ratio of means, RoM), we review four point estimators of $\tau^2$ (the popular methods of DerSimonian-Laird (DL), restricted maximum likelihood, and Mandel and Paule (MP), and the less-familiar method of Jackson), four interval estimators for $\tau^2$ (profile likelihood, Q-profile, Biggerstaff and Jackson, and Jackson), five point estimators of the overall effect (the four related to the point estimators of $\tau^2$ and an estimator whose weights use only study-level sample sizes), and seven interval estimators for the overall effect (four based on the point estimators for $\tau^2$, the Hartung-Knapp-Sidik-Jonkman (HKSJ) interval, a modification of HKSJ that uses the MP estimator of $\tau^2$ instead of the DL estimator, and an interval based on the sample-size-weighted estimator). We obtain empirical evidence from extensive simulations of data from normal distributions. Simulations from lognormal distributions are in a separate report Bakbergenuly et al. 2019b.

scholarly journals 10 Years of Pulsed-Xenon Ultraviolet Disinfection

2020 ◽  
Vol 41 (S1) ◽  
pp. s438-s438
Author(s):  
Mark Stibich ◽  
Sarah Simmons ◽  
Deborah Passey
Keyword(s):  
Relative Risk ◽  
Meta Analysis ◽  
Outcome Studies ◽  
Uv Disinfection ◽  
Clostridioides Difficile ◽  
Environmental Effectiveness ◽  
Meta Analyses ◽  
Hospital Acquired ◽  
And Control ◽  
Effectiveness Studies

Background: Ultraviolet light (UV) disinfection using low-pressure mercury lamps has been around since the 1940s. The advent of pulsed-xenon UV for hospital use in 2010 has provided a nontoxic and novel technology for hospital disinfection with the first data presented at the 2010 SHEA Decennial. The purpose of this systematic review and meta-analysis is to examine the current body of evidence for pulsed xenon UV disinfection. Methods: The literature search criteria included the following: research conducted in domestic and international settings using pulsed-xenon for surface disinfection, published between 2000 and 2019, and reporting on environmental effectiveness or hospital-acquired reductions (HAIs). We searched PubMed, Google Scholar, and Web of Science. The meta-analysis included 24 studies: 12 HAI outcome studies and 12 environmental effectiveness studies. Meta-analyses were conducted by calculating the percentage reductions for environmental effectiveness, and for the HAI outcome studies, we used a random-effects model to pool the relative risk of HAI. The outcome studies used 272 and 299 months of data for the experimental and control groups, respectively. Results: There was an overall benefit of using pulsed-xenon UV. The overall relative risk of infection decreased compared to the control arm (RR, 0.64; 95% CI, 0.54–0.76). The percentage reductions in environmental studies were as follows: Clostridioides difficile (94.8%), methicillin-resistant Staphylococcus aureus (91.5%), vancomycin-resistant Enterococcus (99.2%), and aerobic bacteria (94.2%). Conclusions: Overall, pulsed-xenon UV was effective for reducing environmental contamination and had the ability to significantly reduce HAIs.Funding: Xenex, Inc., funded this study.Disclosures: Mark Stibich receives a salary from Xenex and is a shareholder of Xenex. Deborah Passey receives a salary from Xenex Disinfection Services.

scholarly journals Lifetime prevalence of non-suicidal self-injury in patients with eating disorders: a systematic review and meta-analysis

2016 ◽  
Vol 46 (7) ◽  
pp. 1345-1358 ◽  
Author(s):  
A. Cucchi ◽  
D. Ryan ◽  
G. Konstantakopoulos ◽  
S. Stroumpa ◽  
A. Ş. Kaçar ◽  
...  
Keyword(s):  
Substance Abuse ◽  
Eating Disorders ◽  
Suicide Attempts ◽  
Meta Analysis ◽  
Weighted Average ◽  
Average Percentage ◽  
Lifetime History ◽  
Self Injury ◽  
History Of ◽  
Meta Analyses

BackgroundAgainst a backdrop of increasing research, clinical and taxonomic attention in non-suicidal self-injury (NSSI), evidence suggests a link between NSSI and eating disorders (ED). The frequency estimates of NSSI in ED vary widely. Little is known about the sources of this variation, and no meta-analysis has quantified the association between ED and NSSI.MethodUsing random-effects meta-analyses, meta-regression analyses, and 1816–6466 unique participants with various ED, we estimated the weighted average percentage of individuals with ED, those with anorexia nervosa (AN) and those with bulimia nervosa (BN) who are reported to have a lifetime history of NSSI across studies. We further examined predictors of NSSI in ED.ResultsThe weighted average percentage of patients with a lifetime history of NSSI was 27.3% [95% confidence interval (CI) 23.8–31.0%] for ED, 21.8% (95% CI 18.5–25.6%) for AN, and 32.7% (95% CI 26.9–39.1%) for BN. The difference between BN and AN was statistically significant [odds ratio (OR) 1.77, 95% CI 1.14–2.77, p = 0.013]. The odds of NSSI increased by 24% for every 10% increase in the percentage of participants with histories of suicide attempts (OR 1.24, 95% CI 1.04–1.48, p = 0.020) and decreased by 26% for every 10% increase in the percentage of participants with histories of substance abuse (OR 0.74, 95% CI 0.58–0.95, p = 0.023).ConclusionsIn the specific context of ED, NSSI is highly prevalent and correlates positively with attempted suicide, urging for NSSI-focused treatments. A novel finding is that NSSI is potentially antagonized by substance abuse.

scholarly journals Interval estimation of the overall treatment effect in random-effects meta-analyses: Recommendations from a simulation study comparing frequentist, Bayesian, and bootstrap methods

2020 ◽  
Author(s):  
Frank Weber ◽  
Guido Knapp ◽  
Anne Glass ◽  
Günther Kundt ◽  
Katja Ickstadt
Keyword(s):  
Literature Review ◽  
Random Effects ◽  
Simulation Study ◽  
Treatment Effect ◽  
Profile Likelihood ◽  
Meta Analysis ◽  
Artery Bypass ◽  
Interval Length ◽  
Interval Estimators ◽  
Meta Analyses

There exists a variety of interval estimators for the overall treatment effect in a random-effects meta-analysis. A recent literature review summarizing existing methods suggested that in most situations, the Hartung-Knapp/Sidik-Jonkman (HKSJ) method was preferable. However, a quantitative comparison of those methods in a common simulation study is still lacking. Thus, we conduct such a simulation study for continuous and binary outcomes, focusing on the medical field for application.Based on the literature review and some new theoretical considerations, a practicable number of interval estimators is selected for this comparison: the classical normal-approximation interval using the DerSimonian-Laird heterogeneity estimator, the HKSJ interval using either the Paule-Mandel or the Sidik-Jonkman heterogeneity estimator, the Skovgaard higher-order profile likelihood interval, a parametric bootstrap interval, and a Bayesian interval using different priors. We evaluate the performance measures (coverage and interval length) at specific points in the parameter space, i.e. not averaging over a prior distribution. In this sense, our study is conducted from a frequentist point of view.We confirm the main finding of the literature review, the general recommendation of the HKSJ method (here with the Sidik-Jonkman heterogeneity estimator). For meta-analyses including only 2 studies, the high length of the HKSJ interval limits its practical usage. In this case, the Bayesian interval using a weakly informative prior for the heterogeneity may help. Our recommendations are illustrated using a real-world meta-analysis dealing with the efficacy of an intramyocardial bone marrow stem cell transplantation during coronary artery bypass grafting.

Interventions for Adolescents With ADHD to Improve Peer Social Functioning: A Systematic Review and Meta-Analysis

2020 ◽  
pp. 108705472090651 ◽  
Author(s):  
Sarah Morris ◽  
Jade Sheen ◽  
Mathew Ling ◽  
Denise Foley ◽  
Emma Sciberras
Keyword(s):  
Social Functioning ◽  
Randomized Trials ◽  
Meta Analysis ◽  
Parent Report ◽  
Self Report ◽  
Age Group ◽  
Control Groups ◽  
Social Interventions ◽  
Meta Analyses ◽  
And Control

Objective: Peer social functioning difficulties characteristic of ADHD persist into adolescence, but the efficacy of interventions for this age group remains unclear. Method: A systematic search of nonpharmacological interventions for adolescents with ADHD (10–18 years) identified 11 trials addressing social functioning, of which eight were included in meta-analyses. Results: Random effects meta-analyses of four randomized trials found no differences in social functioning between treatment and control groups by parent- ( g = −0.08 [−0.34, 0.19], k = 4, N = 354) or teacher-report ( g = 0.17 [−0.06, 0.40], k = 3, N = 301). Meta-analyses of nonrandomized studies indicated participants’ social functioning improved from baseline to postintervention by parent-report, but not teacher- or self-report. All trials had a high risk of bias. Conclusion: These results highlight the paucity of research in this age group. There is little evidence that current interventions improve peer social functioning. Clearer conceptualizations of developmentally relevant targets for remediation may yield more efficacious social interventions.

scholarly journals A systematic review and meta-analysis of randomized controlled trials for the reduction of surgical site infection in closed incision management versus standard of care dressings over closed vascular groin incisions

Vascular ◽  
2020 ◽  
Vol 28 (3) ◽  
pp. 274-284 ◽  
Author(s):  
Alexander Gombert ◽  
Ellen Dillavou ◽  
Ralph D’Agostino ◽  
Leah Griffin ◽  
Julie M Robertson ◽  
...  
Keyword(s):  
Vascular Surgery ◽  
Surgical Site Infection ◽  
Meta Analysis ◽  
Site Infection ◽  
Infection Rates ◽  
Control Groups ◽  
Randomized Controlled ◽  
Risk Patients ◽  
Meta Analyses ◽  
And Control

Objective Surgical site infection after groin incision is a common complication and a financial burden to patients and healthcare systems. Closed incision negative pressure therapy (ciNPT) has been associated with decreased surgical site infection rates in published literature. This meta-analysis examines the effect of ciNPT (PREVENA™ Incision Management System; KCI, San Antonio, TX) versus traditional postsurgical dressing use in reducing surgical site infection rates over closed groin incisions following vascular surgery. Methods A systematic literature search using PubMed, OVID, EMBASE, and QUOSA was performed on 3 January 2019, by two independent researchers and focused on publications between 1 January 2005 and 31 December 2018. The review conformed to the statement and reporting check list of the Preferred Reporting Items for Systematic Reviews and Meta Analyses. Inclusion criteria included abstract or manuscript written in English, published studies, conference abstracts, randomized controlled trials (RCTs), ciNPT usage over closed groin incisions in vascular surgery, comparison of ciNPT use and traditional dressings, study endpoint/outcome of surgical site infection, and study population of >10. Characteristics of study participants, surgical procedure, type of dressing used, duration of treatment, incidence of surgical site infection, and length of follow-up were extracted. Weighted odds ratios and 95% confidence intervals were calculated to pool study and control groups in each publication for analysis. Treatment effects were combined using Mantel-Haenszel risk ratios, and the Chi-Square test was used to assess heterogeneity. Overall, high-risk patients, normal-risk patients, and Szilagyi I, II, III outcomes were assessed between ciNPT and control groups. The Cochrane Collaboration tool was utilized to assess the risk of bias for all studies included in the analysis. Results A total of 615 articles were identified from the literature search. After removal of excluded studies and duplicates, six RCT studies were available for analysis. In these studies, a total of 362 patients received ciNPT, and 371 patients received traditional dressings (control). Surgical site infection events occurred in 41 ciNPT patients and 107 control patients. The heterogeneity test was nonsignificant ( p > 0.05). The overall RCT meta-analysis showed a highly significant effect in favor of ciNPT (OR = 3.06, 95% CI [2.05, 4.58], p < 0.05). High-risk, normal-risk, Szilagyi I, and Szilagyi II meta-analyses were also statistically significant in favor of ciNPT use ( p < 0.05). The varying RCT inclusion/exclusion criteria, such as differences in procedure types, and patient populations form the major limitations of this study. Conclusions A statistically significant reduction in the incidence of surgical site infection was seen following ciNPT usage in patients undergoing vascular surgery with groin incisions.

scholarly journals Elucidating the Role of Cerebellar Synaptic Dysfunction in C9orf72-ALS/FTD — a Systematic Review and Meta-Analysis

2021 ◽  
Author(s):  
Aleksandra Kaliszewska ◽  
Joseph Allison ◽  
Tarik-Tarkan Col ◽  
Christopher Shaw ◽  
Natalia Arias
Keyword(s):  
Meta Analysis ◽  
Neuronal Loss ◽  
Synaptic Dysfunction ◽  
Protein Levels ◽  
Hexanucleotide Repeat ◽  
Gene Dysregulation ◽  
Rna Foci ◽  
Synaptic Neurotransmission ◽  
Meta Analyses ◽  
And Control

AbstractA hexanucleotide repeat expansion in the C9orf72 gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) with synaptic dysfunction identified as an early pathological hallmark. Although TDP-43 pathology and overt neurodegeneration are largely absent from the cerebellum, the pathological hallmarks of RNA foci and dipeptide repeat protein (DPR) inclusions are most abundant. Here, we present a systematic literature search in the databases of PubMed, Scopus, Embase, Web of Science and Science Direct up until March 5, 2021, which yielded 19,515 publications. Following the exclusion criteria, 72 articles were included having referred to C9orf72, synapses and the cerebellum. Meta-analyses were conducted on studies which reported experimental and control groups with means and standard deviations extracted from figures using the online tool PlotDigitizer. This revealed dendritic defects (P = 0.03), reduced C9orf72 in human patients (P = 0.005) and DPR-related neuronal loss (P = 0.0006) but no neuromuscular junction abnormalities (P = 0.29) or cerebellar neuronal loss (P = 0.23). Our results suggest that dendritic arborisation defects, synaptic gene dysregulation and altered synaptic neurotransmission may drive cerebellar synaptic dysfunction in C9-ALS/FTD. In this review, we discuss how the chronological appearance of the different pathological hallmarks alters synaptic integrity which may have profound implications for disease progression. We conclude that a reduction in C9orf72 protein levels combined with the accumulation of RNA foci and DPRs act synergistically to drive C9 synaptopathy in the cerebellum of C9-ALS/FTD patients.

scholarly journals Blood-Based ATN Biomarkers of Alzheimer’s Disease: A Meta-Analysis

2021 ◽  
Vol 79 (1) ◽  
pp. 177-195
Author(s):  
Ivan Koychev ◽  
Katrin Jansen ◽  
Alina Dette ◽  
Liu Shi ◽  
Heinz Holling
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Single Molecule ◽  
Meta Analysis ◽  
Random Effect ◽  
Neurofilament Light ◽  
Meta Analyses ◽  
And Control ◽  
T Tau ◽  
Biological State

Background: The Amyloid Tau Neurodegeneration (ATN) framework was proposed to define the biological state underpinning Alzheimer’s disease (AD). Blood-based biomarkers offer a scalable alternative to the costly and invasive currently available biomarkers. Objective: In this meta-analysis we sought to assess the diagnostic performance of plasma amyloid (Aβ40, Aβ42, Aβ42/40 ratio), tangle (p-tau181), and neurodegeneration (total tau [t-tau], neurofilament light [NfL]) biomarkers. Methods: Electronic databases were screened for studies reporting biomarker concentrations for AD and control cohorts. Biomarker performance was examined by random-effect meta-analyses based on the ratio between biomarker concentrations in patients and controls. Results: 83 studies published between 1996 and 2020 were included in the analyses. Aβ42/40 ratio as well as Aβ42 discriminated AD patients from controls when using novel platforms such as immunomagnetic reduction (IMR). We found significant differences in ptau-181 concentration for studies based on single molecule array (Simoa), but not for studies based on IMR or ELISA. T-tau was significantly different between AD patients and control in IMR and Simoa but not in ELISA-based studies. In contrast, NfL differentiated between groups across platforms. Exosome studies showed strong separation between patients and controls for Aβ42, t-tau, and p-tau181. Conclusion: Currently available assays for sampling plasma ATN biomarkers appear to differentiate between AD patients and controls. Novel assay methodologies have given the field a significant boost for testing these biomarkers, such as IMR for Aβ, Simoa for p-tau181. Enriching samples through extracellular vesicles shows promise but requires further validation.

scholarly journals Interactive Features of E-Texts’ Effects on Learning: A Systematic Review and Meta-analysis

2021 ◽  
Author(s):  
Virginia Clinton-Lisell
Keyword(s):  
Systematic Review ◽  
Meta Analysis ◽  
Reading Performance ◽  
Systematic Search ◽  
Future Directions ◽  
Positive Effects ◽  
Collaborative Tools ◽  
Meta Analyses ◽  
And Control

E-texts afford interactive features that are not feasible with paper texts. Several studies have been conducted examining interactive features of e-texts, but it is uncertain what the overall effect is or what features may be most useful. The purpose of this study is to systematically review and meta-analyze the findings comparing reading performance and/or reading times between e-texts with interactive features and control texts (paper or static e-texts). The systematic search of the literature identified 26 independent studies on reading performance. Based on the meta-analyses, interactive features benefited reading performance (g = .66, p &lt; .001). Individual studies with positive effects involved multiple interactive features; however, potential contributions of three types of features (questions with feedback, digital glossaries, and collaborative tools) are discussed. Future directions for examining interactive features experimentally to better understand what features are most helpful for whom are described.

scholarly journals Periodontal Outcomes in Liver Transplantation Individuals: A Systematic Review and Meta-analysis

2021 ◽  
Vol 30 (1) ◽  
pp. 122-131
Author(s):  
Tuélita Marques Galdino ◽  
Carla Souza Oliveira ◽  
Allyson Nogueira Moreira ◽  
Francisco Ivison Rodrigues Limeira ◽  
Cláudia Silami Magalhães ◽  
...  
Keyword(s):  
Alveolar Bone ◽  
Meta Analysis ◽  
Grey Literature ◽  
Mean Difference ◽  
Control Group ◽  
Clinical Attachment Level ◽  
Probing Depth ◽  
Meta Analyses ◽  
And Control ◽  
Attachment Level

Aim: To systematically review the literature for observational studies evaluating periodontal outcomes in pre- and post-liver transplant (LT) individuals compared to a control group. Methods: Specific strategies were designed to search five databases and the grey literature. Hand-searches were also performed. The following periodontal outcomes were analyzed in pre-LT, post-LT and control groups: plaque index (PI), gingival index (GI), gingival growth (GO), alveolar bone loss (ABL) probing depth (PD) and clinical attachment level (CAL). Meta-analyses and subgroup analyses were conducted. Results: Among the 257 studies retrieved, 11 studies were included. Four studies were incorporated into the meta-analysis and showed that PI (mean difference=0.15, 95%CI: 0.12-0.18) and GI (mean difference=0.31, 95%CI: 0.06-0.56) were significantly higher in post-LT individuals compared to the control group. There was no significant mean difference of PD (mean difference=0.49, 95%CI: -0.26-1.25) but CAL (mean differ- ence=1.47, 95%CI: 0.19-2.75) were significantly higher in pre-LT individuals compared to the control group. Conclusion: The higher means of PI and GI in post-LT and CAL in pre-LT compared to healthy individuals suggest a relationship between the periodontal condition and the transplantation status.

Sign in / Sign up

Export Citation Format

Share Document