Human studies of mitochondrial biology demonstrate an overall lack of binary sex differences: A multivariate meta-analysis

Mitochondria are maternally inherited organelles that play critical tissue-specific roles, including hormone synthesis and energy production, that influence development, health, and aging. However, whether mitochondria from women and men exhibit consistent biological differences remains unclear, representing a major gap in biomedical knowledge. This meta-analysis systematically examined 4 domains and 6 subdomains of mitochondrial biology (total 39 measures), including mitochondrial content, respiratory capacity, reactive oxygen species (ROS) production, morphometry, and mitochondrial DNA copy number. Standardized effect sizes (Hedges g) of sex differences were computed for each measure using data in 2,258 participants (51.5% women) from 50 studies. Only two measures demonstrated aggregate binary sex differences: higher mitochondrial content in women (g = 0.20, chi2 p = 0.01), and higher ROS production in skeletal muscle in men (g = 0.49, chi2 p < 0.0001). Sex differences showed weak to no correlation with age or BMI. Studies with small sample sizes tended to overestimate effect sizes (r = -0.17, p < 0.001), and sex differences varied by tissue examined. Our findings point to a wide variability of findings in the literature concerning possible binary sex differences in mitochondrial biology. Studies specifically designed to capture sex- and gender-related differences in mitochondrial biology are needed, including detailed considerations of physical activity and sex hormones.

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Influence of Pilot and Small Trials in Meta-Analyses of Behavioral Interventions: A Meta-epidemiological Study

10.21203/rs.3.rs-46722/v1 ◽

2020 ◽

Author(s):

Michael W. Beets ◽

R. Glenn Weaver ◽

John P.A. Ioannidis ◽

Alexis Jones ◽

Lauren von Klinggraeff ◽

...

Keyword(s):

Sample Size ◽

Behavioral Interventions ◽

Meta Analysis ◽

Statistical Significance ◽

Feasibility Studies ◽

Small Sample ◽

Effect Sizes ◽

Absolute Difference ◽

Meta Analyses ◽

The Impact

Abstract Background: Pilot/feasibility or studies with small sample sizes may be associated with inflated effects. This study explores the vibration of effect sizes (VoE) in meta-analyses when considering different inclusion criteria based upon sample size or pilot/feasibility status. Methods: Searches were conducted for meta-analyses of behavioral interventions on topics related to the prevention/treatment of childhood obesity from 01-2016 to 10-2019. The computed summary effect sizes (ES) were extracted from each meta-analysis. Individual studies included in the meta-analyses were classified into one of the following four categories: self-identified pilot/feasibility studies or based upon sample size (N≤100, N>100, and N>370 the upper 75th of sample size). The VoE was defined as the absolute difference (ABS) between the re-estimations of summary ES restricted to study classifications compared to the originally reported summary ES. Concordance (kappa) of statistical significance between summary ES was assessed. Fixed and random effects models and meta-regressions were estimated. Three case studies are presented to illustrate the impact of including pilot/feasibility and N≤100 studies on the estimated summary ES.Results: A total of 1,602 effect sizes, representing 145 reported summary ES, were extracted from 48 meta-analyses containing 603 unique studies (avg. 22 avg. meta-analysis, range 2-108) and included 227,217 participants. Pilot/feasibility and N≤100 studies comprised 22% (0-58%) and 21% (0-83%) of studies. Meta-regression indicated the ABS between the re-estimated and original summary ES where summary ES were comprised of ≥40% of N≤100 studies was 0.29. The ABS ES was 0.46 when summary ES comprised of >80% of both pilot/feasibility and N≤100 studies. Where ≤40% of the studies comprising a summary ES had N>370, the ABS ES ranged from 0.20-0.30. Concordance was low when removing both pilot/feasibility and N≤100 studies (kappa=0.53) and restricting analyses only to the largest studies (N>370, kappa=0.35), with 20% and 26% of the originally reported statistically significant ES rendered non-significant. Reanalysis of the three case study meta-analyses resulted in the re-estimated ES rendered either non-significant or half of the originally reported ES. Conclusions: When meta-analyses of behavioral interventions include a substantial proportion of both pilot/feasibility and N≤100 studies, summary ES can be affected markedly and should be interpreted with caution.

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A Meta-Analysis Shows That Screen Bottom Boards Can Significantly Reduce Varroa destructor Population

Insects ◽

10.3390/insects11090624 ◽

2020 ◽

Vol 11 (9) ◽

pp. 624

Author(s):

Fang Liu ◽

Xinjian Xu ◽

Yuan Zhang ◽

Hongxia Zhao ◽

Zachary Y. Huang

Keyword(s):

Apis Mellifera ◽

Honey Bee ◽

Varroa Destructor ◽

Negative Impact ◽

Meta Analysis ◽

Small Sample ◽

Effect Sizes ◽

Negative Results ◽

Mite Control ◽

Small Sample Sizes

Varroa destructor is by far the most serious threat to the western honey bee, Apis mellifera. A screen bottom board, a cultural method for mite control, is a modified bottom board with a screen that allows mites to fall onto a sticky board, or the grass or soil below the screen. Whether or not a screen bottom board can reduce varroa significantly has been controversial. Most studies show a trend of lower varroa populations in colonies with these boards, but the results are usually not statistically significant. To understand whether the negative results have been due to small sample sizes, or because the board is actually ineffective, we conducted a meta-analysis with seven published studies with a total of 145 colonies. Meta-analysis showed that the confidence intervals of the combined effect sizes were negative with a Hedges’ g of −1.09 (SE 0.39, 95% CI −2.0 to −0.19, p < 0.01), which suggests that the varroa population in colonies with screen bottom boards is significantly lower compared to those with traditional wooden floors. We thus conclude that the screen bottom board does have a significantly negative impact on the varroa population and can be part of tool kits for mite control.

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Unsuccessful Treatments of “Writer's Block”: A Meta-Analysis

Psychological Reports ◽

10.2466/28.pr0.115c12z0 ◽

2014 ◽

Vol 115 (1) ◽

pp. 276-278 ◽

Cited By ~ 2

Author(s):

Derrick C. McLean ◽

Benjamin R. Thomas

Keyword(s):

Meta Analysis ◽

Small Sample ◽

The Body ◽

Effect Sizes ◽

Sample Sizes ◽

Writer's Block ◽

Unsuccessful Treatment ◽

Group Treatments ◽

Writer’S Block ◽

Small Sample Sizes

A wide literature of the unsuccessful treatment of writer's block has emerged since the early 1970's. Findings within this literature seem to confer generalizability of this procedure; however, small sample sizes may limit this interpretation. This meta-analysis independently analyzed effect sizes for “self-treatments” and “group-treatments” using number of words in the body of the publication as indication of a failure to treat writer's block. Results of the reported findings suggest that group-treatments tend to be slightly more unsuccessful than self-treatments.

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Hydroxychloroquine and mortality risk of patients with COVID-19: a systematic review and meta-analysis of human comparative studies

10.1101/2020.06.17.20133884 ◽

2020 ◽

Author(s):

Thibault Fiolet ◽

Anthony Guihur ◽

Mathieu Rebeaud ◽

Matthieu Mulot ◽

Yahya Mahamat-Saleh

Keyword(s):

Systematic Review ◽

Relative Risk ◽

Mortality Risk ◽

Standard Care ◽

Meta Analysis ◽

Grey Literature ◽

Small Sample ◽

Hospitalized Patients ◽

Effect Sizes ◽

Cochrane Library

AbstractBackgroundGlobal COVID-19 deaths reached at least 400,000 fatalities. Hydroxychloroquine is an antimalarial drug that elicit immunomodulatory effects and had shown in vitro antiviral effects against SRAS-CoV-2. This drug divided opinion worldwide in the medical community but also in the press, the general public and in public health policies. The aim of this systematic review and this meta-analysis was to bring a new overview on this controversial drug and to assess whether hydroxychloroquine could reduce COVID-19 mortality risk in hospitalized patients.Methods and FindingsPubmed, Web of Science, Cochrane Library, MedRxiv and grey literature were searched until 10 June 2020. Only studies of COVID-19 patients treated with hydroxychloroquine (with or without azithromycin) compared with a comparative standard care group and with full-text articles in English were included. Studies reporting effect sizes as Odds Ratios, Hazard Ratio and Relative Risk for mortality risk and the number of deaths per groups were included. This meta-analysis was conducted following PRISMA guidelines and registered on PROSPERO (Registration number: CRD42020190801). Independent extraction has been performed by two independent reviewers. Effect sizes were pooled using a random-effects model.The initial search leaded to 112 articles, from which 16 articles met our inclusion criteria. 15 studies were retained for association between hydroxychloroquine and COVID-19 survival including 15,081 patients (8,072 patients in the hydroxychloroquine arm and 7,009 patients in the standard care arm with respectively, 1,578 deaths and 1,423 deaths). 6 studies were retained for hydroxychloroquine with azithromycin. Hydroxychloroquine was not significantly associated with mortality risk (pooled Relative Risk RR=0.82 (95% Confidence Interval: 0.62-1.07, I2=82, Pheterogeneity<0.01, n=15)) within hospitalized patients, nor in association with azithromycin (pooled Relative Risk RR=1.33 (95% CI: 0.92-1.92, I2=75%, Pheterogeneity<0.01, n=6)), nor in the numerous subgroup analysis by study design, median age population, published studies (vs unpublished articles), level of bias risk. However, stratified analysis by continents, we found a significant decreased risk of mortality associated with hydroxychlroquine alone but not with azithromycin among European (RR= 0.62 (95%CI: 0.41-0.93, n=7)) and Asian studies (RR=0.36 (95%CI:0.18-0.73, n=1)), with heterogeneity detected across continent (Pheterogeneity between=0.003). These finding should be interpreted with caution since several included studies had a low quality of evidence with a small sample size, a lack of adjustment on potential confounders or selection and intervention biases.ConclusionOur meta-analysis does not support the use of hydroxychloroquine with or without azithromycin to reduce COVID-19 mortality in hospitalized patients. It raises the question of the hydroxychloroquine use outside of clinical trial. Additional results from larger randomised controlled trials are needed

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Comparison of Within- and Between-Series Effect Estimates in the Meta-Analysis of Multiple Baseline Studies

Journal of Educational and Behavioral Statistics ◽

10.3102/10769986211035507 ◽

2021 ◽

pp. 107699862110355

Author(s):

Seang-Hwane Joo ◽

Yan Wang ◽

John Ferron ◽

S. Natasha Beretvas ◽

Mariola Moeyaert ◽

...

Keyword(s):

Effect Size ◽

Mean Squared Error ◽

Meta Analysis ◽

Small Sample ◽

Effect Sizes ◽

Alternative Methods ◽

Multiple Baseline ◽

Simulation Studies ◽

Squared Error ◽

Size Estimates

Multiple baseline (MB) designs are becoming more prevalent in educational and behavioral research, and as they do, there is growing interest in combining effect size estimates across studies. To further refine the meta-analytic methods of estimating the effect, this study developed and compared eight alternative methods of estimating intervention effects from a set of MB studies. The methods differed in the assumptions made and varied in whether they relied on within- or between-series comparisons, modeled raw data or effect sizes, and did or did not standardize. Small sample functioning was examined through two simulation studies, which showed that when data were consistent with assumptions the bias was consistently less than 5% of the effect size for each method, whereas root mean squared error varied substantially across methods. When assumptions were violated, substantial biases were found. Implications and limitations are discussed.

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Delay Discounting in Established and Proposed Behavioral Addictions: A Systematic Review and Meta-Analysis

Frontiers in Behavioral Neuroscience ◽

10.3389/fnbeh.2021.786358 ◽

2021 ◽

Vol 15 ◽

Author(s):

Sarah Weinsztok ◽

Sarah Brassard ◽

Iris Balodis ◽

Laura E. Martin ◽

Michael Amlung

Keyword(s):

Systematic Review ◽

Delay Discounting ◽

Gambling Disorder ◽

Food Addiction ◽

Meta Analysis ◽

Small Sample ◽

Behavioral Addiction ◽

Effect Sizes ◽

Behavioral Addictions ◽

Small Magnitude

Steep delay discounting, or a greater preference for smaller-immediate rewards over larger-delayed rewards, is a common phenomenon across a range of substance use and psychiatric disorders. Non-substance behavioral addictions (e.g., gambling disorder, internet gaming disorder, food addiction) are of increasing interest in delay discounting research. Individual studies have reported steeper discounting in people exhibiting various behavioral addictions compared to controls or significant correlations between discounting and behavioral addiction scales; however, not all studies have found significant effects. To synthesize the published research in this area and identify priorities for future research, we conducted a pre-registered systematic review and meta-analysis (following PRISMA guidelines) of delay discounting studies across a range of behavioral addiction categories. The final sample included 78 studies, yielding 87 effect sizes for the meta-analysis. For studies with categorical designs, we found statistically significant, medium-to-large effect sizes for gambling disorder (Cohen’s d = 0.82) and IGD (d = 0.89), although the IGD effect size was disproportionately influenced by a single study (adjusted d = 0.53 after removal). Categorical internet/smartphone studies were non-significant (d = 0.16, p = 0.06). Aggregate correlations in dimensional studies were statistically significant, but generally small magnitude for gambling (r = 0.22), internet/smartphone (r = 0.13) and food addiction (r = 0.12). Heterogeneity statistics suggested substantial variability across studies, and publication bias indices indicated moderate impact of unpublished or small sample studies. These findings generally suggest that some behavioral addictions are associated with steeper discounting, with the most robust evidence for gambling disorder. Importantly, this review also highlighted several categories with notably smaller effect sizes or categories with too few studies to be included (e.g., compulsive buying, exercise addiction). Further research on delay discounting in behavioral addictions is warranted, particularly for categories with relatively few studies.

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Systematic Reviews and Meta-Analyses of Crime Prevention Evaluations

Oxford Research Encyclopedia of Criminology and Criminal Justice ◽

10.1093/acrefore/9780190264079.013.388 ◽

2018 ◽

Author(s):

Anthony Petrosino ◽

Claire Morgan ◽

Trevor Fronius

Keyword(s):

Systematic Review ◽

Systematic Reviews ◽

Effect Size ◽

Meta Analysis ◽

Experimental Studies ◽

Small Sample ◽

Effect Sizes ◽

What Works ◽

Management Procedures ◽

Meta Analyses

Systematic reviews and meta-analyses have become a focal point of evidence-based policy in criminology. Systematic reviews use explicit and transparent processes to identify, retrieve, code, analyze, and report on existing research studies bearing on a question of policy or practice. Meta-analysis can combine the results from the most rigorous evaluations identified in a systematic review to provide policymakers with the best evidence on what works for a variety of interventions relevant to reducing crime and making the justice system fairer and more effective. The steps of a systematic review using meta-analysis include specifying the topic area, developing management procedures, specifying the search strategy, developing eligibility criteria, extracting data from the studies, computing effect sizes, developing an analysis strategy, and interpreting and reporting the results. In a systematic review using meta-analysis, after identifying and coding eligible studies, the researchers create a measure of effect size for each experimental versus control contrast of interest in the study. Most commonly, reviewers do this by standardizing the difference between scores of the experimental and control groups, placing outcomes that are conceptually similar but measured differently (e.g., such as re-arrest or reconviction) on the same common scale or metric. Though these are different indices, they do measure a program’s effect on some construct (e.g., criminality). These effect sizes are usually averaged across all similar studies to provide a summary of program impact. The effect sizes also represent the dependent variable in the meta-analysis, and more advanced syntheses explore the role of potential moderating variables, such as sample size or other characteristics related to effect size. When done well and with full integrity, a systematic review using meta-analysis can provide the most comprehensive assessment of the available evaluative literature addressing the research question, as well as the most reliable statement about what works. Drawing from a larger body of research increases statistical power by reducing standard error; individual studies often use small sample sizes, which can result in large margins of error. In addition, conducting meta-analysis can be faster and less resource-intensive than replicating experimental studies. Using meta-analysis instead of relying on an individual program evaluation can help ensure that policy is guided by the totality of evidence, drawing upon a solid basis for generalizing outcomes.

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Sex Differences in the Association Between Obesity and Hypertension: A Systematic Review

Sciential - McMaster Undergraduate Science Journal ◽

10.15173/sciential.vi6.2720 ◽

2021 ◽

pp. 2-3

Author(s):

Ava Oliaei

Keyword(s):

Systematic Review ◽

Sex Differences ◽

Meta Analysis ◽

Small Sample ◽

Obese Women ◽

Life Years ◽

Health Related ◽

The Difference ◽

Small Sample Sizes ◽

Meta Analyses

Introduction: Obesity is associated with multiple health-related complications, which together can decrease quality of life, disability-adjusted life years and life expectancy.1 Systematic reviews and meta-analyses have demonstrated that sex can influence the association between obesity and health complications, such as rheumatoid arthritis and many types of cancer.2-4 However, no systematic review or meta-analysis has been conducted to review the effect of sex on the association between obesity and hypertension, thus far. Knowing whether or not sex influences this relationship can help tailor the prevention, prediction, and care of this condition towards each sex. Objectives: To evaluate current studies on the association between sex, obesity, and hypertension, so as to obtain an overall estimate of the effect of sex on the prevalence of hypertension in obese individuals. Methods: A systematic search of EMBASE, MEDLINE, and PubMed was conducted. Search terms, such as “obesity,” “sex differences,” and “hypertension,” were used to filter results. After reviewing 406 articles, eight articles were included. Results: Four articles showed that obese women were at a greater risk of developing hypertension than obese men.5-8 Conversely, the results of two studies found that obese men are at a greater risk of developing hypertension.9,10 The remaining two studies showed that the difference between the sexes was insignificant.11,12 Discussion/Limitations: Stronger evidence shows that obese women are at a greater risk of developing hypertension than obese men. The two studies that had contradictory conclusions had small sample sizes relative to the other studies. Additionally, the two studies that concluded that both sexes are at a similar risk highlighted that most other studies have determined that obese women are at a greater risk and that their limitations may have caused this discrepancy. Limitations of this review include the limited ethnicity of participants and the use of BMI to classify obesity, which can sometimes lead to misclassification due to varying muscle to fat ratios. These factors limit the generalizability of the results. Conclusion: Obese women are seemingly at a greater risk of developing hypertension than obese men. However, this conclusion remains statistically inconclusive. Therefore, it would be beneficial to complete a meta-analysis in order to conclusively determine which sex is statistically more at risk of developing hypertension, when obese.

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MetaFun: Unveiling sex differences in multiple omics studies through comprehensive functional meta-analysis

10.1101/2021.07.13.451905 ◽

2021 ◽

Author(s):

Pablo Malmierca-Merlo ◽

Ruben Sanchez-Garcia ◽

Ruben Grillo-Risco ◽

Irene Perez-Diez ◽

José Francisco Català-Senent ◽

...

Keyword(s):

Gender Differences ◽

Sex Differences ◽

Statistical Power ◽

Meta Analysis ◽

Sex And Gender ◽

And Gender ◽

Sex And Gender Differences

Sex and gender differences in different health scenarios has been thoroughly acknowledged in the literature, and yet, very scarcely analyzed. To fill the gap, here we present MetaFun, which allows to meta-analyze multiple omics datasets with a sex-based perspective, and to combine different datasets to gain major statistical power and to assist the researcher in understanding these sex differences in the diseases under study. Metafun is freely available at bioinfo.cipf.es/metafun

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Sex Differences in Trust and Trustworthiness - A Meta-Analysis of the Trust Game and the Gift-Exchange Game

10.31234/osf.io/5zbja ◽

2018 ◽

Cited By ~ 1

Author(s):

Olmo Van den Akker ◽

Marcel A. L. M. van Assen ◽

mark van vugt ◽

Jelte M. Wicherts

Keyword(s):

Sex Differences ◽

Sex Difference ◽

Meta Analysis ◽

Gift Exchange ◽

Effect Sizes ◽

Trust Game ◽

Future Research ◽

Analytic Review ◽

The Gift ◽

Meta Analyses

Do men and women differ in trusting behavior? This question is directly relevant to social, economic, and political domains, yet the answer remains elusive. In this paper, we present a meta-analytic review of the literature on sex differences in the trust game and a variant, the gift-exchange game. Informed by both evolutionary and cultural perspectives, we predicted men to be more trusting and women to be more trustworthy in these games. The trust game meta-analyses encompass 77 papers yielding 174 effect sizes based on 17,082 participants from 23 countries, while the gift-exchange game meta-analyses covered 15 papers reporting 35 effect sizes based on 1,362 participants from 19 countries. In the trust game, we found men to be more trusting than women, g = 0.22, but we found no significant sex difference in trustworthiness, g = 0.09. In the gift-exchange game we found no significant sex difference in trust, g = 0.15, yet we did find that men are more trustworthy than women, g = 0.33. The results of the meta-analyses show that the behavior in both games is inconsistent. It seems that when monetary transfers are multiplied men behave more cooperatively than women, but that there are no sex differences when such a multiplier is absent. This “male multiplier effect” is consistent with an evolutionary account emphasizing men’s historical role as resource provider. However, future research needs to substantiate this effect and provide a theoretical framework to explain it.

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