Statistical controversies in meta-analysis: Fixed effects or random effects models?

1991 ◽  
Vol 12 (5) ◽  
pp. 626
Author(s):  
S.G. Thompson ◽  
S.J. Pocock
Keyword(s):  
Random Effects ◽  
Fixed Effects ◽  
Meta Analysis ◽  
Random Effects Models

scholarly journals Association of bisphenol A with puberty timing: a meta-analysis

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hui Meng ◽  
Yunping Zhou ◽  
Yunxia Jiang
Keyword(s):  
Bisphenol A ◽  
Confidence Intervals ◽  
Random Effects ◽  
Strong Correlation ◽  
Fixed Effects ◽  
Meta Analysis ◽  
Random Effects Models ◽  
Study Heterogeneity ◽  
The Relationship ◽  
Prevalence Ratios

AbstractObjectivesThe results of existing studies on bisphenol A (BPA) and puberty timing did not reach a consensus. Thereby we performed this meta-analytic study to explore the association between BPA exposure in urine and puberty timing.MethodsMeta-analysis of the pooled odds ratios (OR), prevalence ratios (PR) or hazards ratios (HR) with 95% confidence intervals (CI) were calculated and estimated using fixed-effects or random-effects models based on between-study heterogeneity.ResultsA total of 10 studies involving 5621 subjects were finally included. The meta-analysis showed that BPA exposure was weakly associated with thelarche (PR: 0.96, 95% CI: 0.93–0.99), while no association was found between BPA exposure and menarche (HR: 0.99, 95% CI: 0.89–1.12; OR: 1.02, 95% CI: 0.73–1.43), and pubarche (OR: 1.00, 95% CI: 0.79–1.26; PR: 1.00, 95% CI: 0.95–1.05).ConclusionsThere was no strong correlation between BPA exposure and puberty timing. Further studies with large sample sizes are needed to verify the relationship between BPA and puberty timing.

scholarly journals Prognostic Role of Matrix Metalloproteinases in Cervical Cancer: A Meta-Analysis

2021 ◽  
Vol 28 ◽  
pp. 107327482110337
Author(s):  
Weiwei Chen ◽  
Shenjiao Huang ◽  
Kun Shi ◽  
Lisha Yi ◽  
Yaqiong Liu ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Matrix Metalloproteinases ◽  
Random Effects ◽  
Fixed Effects ◽  
Prognostic Value ◽  
Meta Analysis ◽  
Free Survival ◽  
Random Effects Models ◽  
Registration Number ◽  
Meta Analyses

Objective Studies have published the association between the expression of matrix metalloproteinases (MMPs) and the outcome of cervical cancer. However, the prognostic value in cervical cancer remains controversial. This meta-analysis was conducted to evaluate the prognostic functions of MMP expression in cervical cancer. Methods A comprehensive search of PubMed, Embase, and Web of Science databases was conducted to identify the eligible studies according to defined selection and excluding criteria and analyzed according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Fixed and random effects models were evaluated through the hazard ratios (HRs) and 95% confidence intervals (CIs) to estimate the overall survival (OS), recurrence-free survival (RFS), and progress-free survival (PFS). Results A total of 18 eligible studies including 1967 patients were analyzed for prognostic value. Totally 16 selected studies including 21 tests were relevant to the cervical cancer OS, 4 studies focused on RFS, and 1 study on PFS. The combined pooled HRs and 95% CIs of OS were calculated with random-effects models (HR = 1.64, 95% CI = 1.01–2.65, P = .000). In the subgroup analysis for OS, there was no heterogeneity in MMP-2 (I2 = .0%, P = .880), MMP-1 (I2 = .0%, P = .587), and MMP-14 (I2 = 28.3%, P = .248). In MMP-7 and MMP-9, the heterogeneities were obvious (I2 = 99.2% ( P = .000) and I2 = 77.9% ( P = .000), respectively). The pooled HRs and 95% CIs of RFS were calculated with fixed-effects models (HR = 2.22, 95% CI = 1.38–3.58, P = .001) and PFS (HR = 2.29, 95% CI = 1.14–4.58, P = .035). Conclusions The results indicated that MMP overexpression was associated with shorter OS and RFS in cervical cancer patients. It suggested that MMP overexpression might be a poor prognostic marker in cervical cancer. Research Registry Registration Number: reviewregistry 1159.

Cytochrome P450 1A1 Gene Polymorphisms and Endometrial Cancer Risk: A Meta-Analysis

2011 ◽  
Vol 21 (2) ◽  
pp. 323-331 ◽  
Author(s):  
Theodoros N. Sergentanis ◽  
Konstantinos P. Economopoulos ◽  
Souzana Choussein ◽  
Nikos F. Vlahos
Keyword(s):  
Cytochrome P450 ◽  
Endometrial Cancer ◽  
Cancer Risk ◽  
Random Effects ◽  
Fixed Effects ◽  
Meta Analysis ◽  
Cytochrome P450 1A1 ◽  
Case Control Studies ◽  
Endometrial Cancer Risk ◽  
Random Effects Models

Introduction:This meta-analysis aims to examine whether the genotype status of Msp1, Ile462Val, and Thr461Asn polymorphisms in cytochrome P450 1A1 (CYP1A1) is associated with endometrial cancer risk.Methods:Eligible case-control studies were identified through search in MEDLINE (end of search: August 2010). Pooled odds ratios (ORs) were appropriately derived from fixed-effects or random-effects models.Results:ConcerningMspI polymorphism, 8 studies were eligible (1456 cases and 2371 controls); 9 studies were eligible (1889 cases and 3662 controls) for Ile462Val and 6 studies were eligible (1272 cases and 2122 controls) for Thr461Asn.MspI polymorphism was not associated with endometrial cancer risk (for heterozygous TC vs TT carriers: OR = 0.83, 95% confidence interval [CI], 0.59-1.15, random effects; for homozygous CC vs TT carriers: OR = 1.00, 95% CI, 0.55-1.82, fixed effects). Similarly, Ile462Val polymorphism was not associated with endometrial cancer risk (for heterozygous Ile/Val vs Ile/Ile carriers: OR = 1.27, 95% CI, 0.78-2.06, random effects; for homozygous Val/Val vs Ile/Ile carriers: OR = 1.16, 95% CI, 0.48-2.81, fixed effects). Accordingly, Thr461Asn status was not significantly associated with endometrial cancer risk. The same results were reproduced in Caucasians.Conclusions:The 3 examined CYP1A1 genotype polymorphisms do not seem to confer any additional risk for endometrial cancer in Caucasians. Accumulation of further data seems mandatory for future race-specific analyses.

scholarly journals An Estimate of Global Anthrax Prevalence in Livestock: A Meta-analysis

2021 ◽  
pp. 1263-1271
Author(s):  
Bylaiah Sushma ◽  
Seema Shedole ◽  
Kuralayanapalya Puttahonnappa Suresh ◽  
Gowda Leena ◽  
Sharanagouda S. Patil ◽  
...  
Keyword(s):  
High Risk ◽  
Random Effects ◽  
Fixed Effects ◽  
Meta Analysis ◽  
Economic Loss ◽  
Control Measures ◽  
Fixed Effects Model ◽  
Random Effects Models ◽  
Online Databases ◽  
Pooled Prevalence

Background and Aim: Anthrax, caused by the soil-borne spore-forming bacteria called Bacillus anthracis, is a zoonotic disease that persists worldwide in livestock and wildlife and infects humans. It is a great hazard to livestock; henceforth, evaluating the global concerns about the disease occurrence in livestock is essential. This study was conducted to estimate the global prevalence of anthrax and predict high-risk regions, which could be an input to veterinarians to take necessary steps to control and avoid the disease. Materials and Methods: A literature review was performed using online databases, namely, PubMed, Google Scholar, Scopus, Biomed Central, and Science Direct, to extract relevant publications worldwide between 1992 and 2020. Initially, 174 articles were selected, and after scrutinizing, 24 articles reporting the prevalence of anthrax were found to be adequate for the final meta-analysis. The statistical study was accompanied by employing fixed effects and random effects models using R. Results: The pooled prevalence of anthrax globally was 28% (95% confidence interval, 26-30%) from 2452 samples through the fixed effects model. Continent-wise subgroup analysis through the random effects model revealed that the pooled prevalence of anthrax was highest in Africa (29%) and least in North America (21%). Conclusion: In these publications, anthrax causes economic loss to farmers and, thus, to the world. Hence, controlling anthrax infections in high-risk regions are essential by implementing appropriate control measures to decrease the effect of the disease, thereby reducing economic loss.

scholarly journals Effects of dutasteride on prostate cancer incidence: A systematic review and meta-analysis

2020 ◽  
Vol 11 (4) ◽  
pp. 7266-7270
Author(s):  
Gyeong-Eun Min ◽  
Haesoo Kim ◽  
Da Eun Lee ◽  
Kisok Kim
Keyword(s):  
Prostate Cancer ◽  
Random Effects ◽  
Fixed Effects ◽  
Meta Analysis ◽  
Adult Males ◽  
Fixed Effects Model ◽  
Random Effects Models ◽  
Benign Prostate Hypertrophy ◽  
Fixed And Random Effects ◽  
Meta Analyses

5-Alpha-reductase inhibitors (5-ARIs) are used in the treatment of benign prostate hypertrophy (BPH). 5-ARIs, such as finasteride and dutasteride, suppress the biosynthesis of dihydrotestosterone (DHT), a precursor of androgen, which is closely related to the incidence of prostate cancer (PCa). A previous meta-analysis demonstrated a relationship between finasteride use and the incidence of PCA. However, there have been no meta-analyses on the relationship between PCa and dutasteride alone. This meta-analysis was performed to examine the prevalence of PCa in adult males taking dutasteride. We searched PubMed for reports regarding PCa risk and dutasteride use. The study was conducted according to the PRISMA guidelines for systematic reviews and meta-analyses. The analytic hierarchy process (AHP) method was used to weight the studies. Odds ratios (ORs), 95% confidence intervals (CIs), and P-values were calculated using fixed- and random-effects models. A total of eight articles were included in the meta-analysis. The overall OR for both the fixed- and random-effects models was 0.669 and the 95% CI for the random-effects model (0.526–0.851; P = 0.006) was wider than that for the fixed effects model (0.548–0.817; P < 0.001). This study confirmed that the incidence of PCa was significantly reduced by taking dutasteride.

scholarly journals Unsaturated Fatty Acid Intake During Periconception and Incidence of Achieving Pregnancy: A Systematic Review and Meta-Analysis

2021 ◽  
Vol 12 ◽  
Author(s):  
Cintia Romina Gatti ◽  
Dalmiro Gomez Ribot ◽  
Javier Mariani ◽  
Alicia Jawerbaum
Keyword(s):  
Systematic Review ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Dietary Intake ◽  
Random Effects ◽  
Unsaturated Fatty Acid ◽  
Fixed Effects ◽  
Meta Analysis ◽  
Random Effects Models ◽  
Positive Effect

Background: Previous studies suggest that maternal diets enriched in unsaturated fatty acids may have a positive effect on pregnancy success. The aim of the present study was to conduct a systematic review and meta-analysis to evaluate whether increased dietary intake of polyunsaturated fatty acids (PUFAs) or monounsaturated fatty acids (MUFAs) during the periconception period has beneficial effects on the achievement of pregnancy in women.Methods: The electronic databases PubMed, Medline and Cochrane Central Register, as well as references in related review articles, were searched to find studies assessing the effects of unsaturated fatty acid dietary intake during the periconception period on the achievement of pregnancy in women. Pregnancy was confirmed by high levels of hCG (biochemical means) and ultrasound confirmation of a gestational sac and heartbeat (clinical means).Results: For the meta-analysis evaluating the effects of periconceptional diets enriched in PUFAs on pregnancy, four articles, providing data on 2,121 patients, were included. Results showed that periconceptional intake of PUFAs has no significant effects on achieving pregnancy compared to controls, according to both the fixed effects and random effects models (RR = 0.99, 95% CI 0.98–1.00). Further secondary analysis considering ω-6 and ω-3 PUFAs separately showed no significant effects on achieving pregnancy compared to controls. On the other hand, for the meta-analysis evaluating the effects of periconceptional diets enriched in MUFAs on achieving pregnancy, five articles, providing data on 2,473 patients, were included. Results showed that periconceptional dietary intake of MUFAs has significant effects on achieving pregnancy compared to controls according to the fixed effects model (RR = 1.03, 95% CI 1.01–1.06, p &lt; 0.02) but not to the random effects model, due to heterogeneity. A secondary meta-analysis excluding one study which led to heterogeneity showed significant effects of MUFAs on achieving pregnancy compared to controls, according to both the fixed effects and random effects models (RR = 1.03, 95% CI 1.01–1.05, p &lt; 0.02).Conclusion: The meta-analysis of published clinical studies suggests that diets enriched in MUFAs, although not those enriched in PUFAs, may have a positive effect on pregnancy success as determined by HCG and ultrasonography.Systematic Review Registration:https://www.crd.york.ac.uk/PROSPERO/display_record.php?ID=CRD42021239355, identifier: CRD42021239355.

scholarly journals Dyslipidaemia and mortality in COVID-19 patients - a meta-analysis

QJM ◽  
2021 ◽  
Author(s):  
Marco Zuin ◽  
Gianluca Rigatelli ◽  
Claudio Bilato ◽  
Carlo Cervellati ◽  
Giovanni Zuliani ◽  
...  
Keyword(s):  
Random Effects ◽  
Mortality Risk ◽  
Meta Analysis ◽  
Random Effect ◽  
Final Analysis ◽  
Short Term ◽  
Random Effects Models ◽  
Pooled Prevalence ◽  
Statistical Heterogeneity ◽  
Trim And Fill

Abstract Objective The prevalence and prognostic implications of pre-existing dyslipidaemia in patients infected by the SARS-CoV-2 remain unclear. To perform a systematic review and meta-analysis of prevalence and mortality risk in COVID-19 patients with pre-existing dyslipidaemia. Methods Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed in abstracting data and assessing validity. We searched MEDLINE and Scopus to locate all the articles published up to January 31, 2021, reporting data on dyslipidaemia among COVID-19 survivors and non-survivors. The pooled prevalence of dyslipidaemia was calculated using a random effects model and presenting the related 95% confidence interval (CI), while the mortality risk was estimated using the Mantel-Haenszel random effects models with odds ratio (OR) and related 95% CI. Statistical heterogeneity was measured using the Higgins I2 statistic. Results Eighteen studies, enrolling 74.132 COVID-19 patients [mean age 70.6 years], met the inclusion criteria and were included in the final analysis. The pooled prevalence of dyslipidaemia was 17.5% of cases (95% CI: 12.3-24.3%, p &lt; 0.0001), with high heterogeneity (I2=98.7%). Pre-existing dyslipidaemia was significantly associated with higher risk of short-term death (OR: 1.69, 95% CI: 1.19-2.41, p = 0.003), with high heterogeneity (I2=88.7%). Due to publication bias, according to the Trim-and-Fill method, the corrected random-effect ORs resulted 1.61, 95% CI 1.13-2.28, p &lt; 0.0001 (one studies trimmed). Conclusions Dyslipidaemia represents a major comorbidity in about 18% of COVID-19 patients but it is associated with a 60% increase of short-term mortality risk.

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