A Bayesian approach to assessing small-study effects in meta-analysis of a binary outcome with controlled false positive rate

Perioperative dexmedetomidine for the prevention of postoperative delirium after cardiac surgery: a systematic review, Bayesian meta-analysis, and Bayesian re-analysis of the DECADE trial

BACKGROUND

Dexmedetomidine is seen as a promising agent for the prevention of postoperative delirium after cardiac surgery, but the largest study (DECADE) paradoxically suggested an increased risk of delirium.

METHODS

Studies were selected using inclusion/exclusion criteria after conducting online database searches for randomised controlled trials. The primary outcome was the incidence of postoperative delirium with a minimum clinically important difference (MCID), defined as an odds ratio >1.20 or <0.84. Publication bias was quantified using Bayesian model averaging. A random-effects meta-analysis with weakly informative priors was performed. Bayesian re-analysis of DECADE using several different priors including a prior based on this meta-analysis (excluding DECADE) was also performed.

RESULTS

We identified 12 eligible randomised controlled trials (3539 participants). The overall pooled effect showed a mean benefit from dexmedetomidine in delirium prevention (odds ratio 0.67 [95% credible interval 0.45, 0.92]), but any definitive evidence of benefit disappeared after accounting for publication bias (odds ratio 1.15 [95% credible interval 0.93, 2.51]). Bayesian re-analysis of the DECADE trial under a vague prior showed a 1.5% posterior probability of any benefit and only a 0.1% probability of an MCID for benefit. Combining DECADE with the unadjusted meta-analysis-derived prior increased the probability of an MCID for benefit to 17.8%, which decreased to 0.2% using the meta-analysis-derived prior adjusted for publication bias.

CONCLUSIONS

Pooled evidence suggests dexmedetomidine is associated with reduced incidence of postoperative delirium; however, this is highly sensitive to the possibility of publication bias. Bayesian re-analysis of the recently published DECADE trial showed the effect of dexmedetomidine differs markedly depending on the weight given to previous studies. Hence, any true benefit from the use of dexmedetomidine over standard care in this population cannot be definitively characterised at present.

SYSTEMATIC REVIEW PROTOCOL

CRD42023401623 (PROSPERO).

Concordance of dengue viral load with disease severity and different clinical manifestations: A systematic review and meta-analysis

INTRODUCTION

Dengue is a common arboviral disease of tropical and sub-tropical regions of the globe with high prevalence rate in South-East Asian region. Association of viral load with dengue disease severity is dependent on various factors like dengue serotype, primary or secondary infection and immune response of an individual. The objective of the study was to evaluate the association of dengue viral load with dengue disease severity like dengue fever (DF), dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS), dengue serotypes and different clinical manifestations detected during dengue like thrombocytopenia, leukopenia and increased liver enzymes.

MATERIALS AND METHODS

The systematic review and meta-analysis [PROSPERO (CRD42024601682)] is prepared by abiding to PRISMA checklist. It includes twenty-nine observational cross-sectional studies, which has compared association of dengue viral load with dengue disease severity, dengue serotypes and different clinical manifestations in dengue patients.

RESULT

A total of 3983 dengue patients were included in the studies out of which 1758 were diagnosed with DF and 2225 were diagnosed with DHF/DSS. Most of the studies were from South-East Asian countries followed by America and Europe. Meta-analysis of the studies revealed that, high viral load was mostly detected in DHF/DSS as compared to DF. Regarding co-relation of viral load, chances of high viral load was more in female patients than male patients. On comparing viral load with different clinical manifestations, it was seen that, the odds of high viral load were more in patients diagnosed with thrombocytopenia and leukopenia, whereas the odds of high viral load were lower in patients diagnosed with increased secretion of liver enzymes.

CONCLUSION

High Viral load had significant association with dengue disease severity. Female patients had high viral load as compared to male patients. Therefore, viral load may be regarded a potential prognostic tool in detecting dengue severity in patients, and studies need to be conducted with sufficient sample size, abiding to a single classification system and measure of outcome to prevent heterogeneity.

A meta-analysis and systematic review of the clinical efficacy and safety of platelet-rich plasma combined with hyaluronic acid (PRP + HA) versus PRP monotherapy for knee osteoarthritis (KOA)

INTRODUCTION

KOA, a chronic degenerative joint disease, is commonly treated with intra-articular HA and PRP, used alone or in combination. However, the efficacy and safety of combination therapy (PRP + HA) remain unclear.

AIM

The aim of this systematic review and meta-analysis is to assess the clinical effectiveness and safety profile of PRP + HA versus PRP monotherapy for KOA.

MATERIAL AND METHODS

A systematic search was conducted using four electronic databases (PubMed, EMBASE, Scopus, and Cochrane Library) to select publications published in peer-reviewed journals. The mean difference (MD) and risk ratio (RR) was calculated, along with their 95% confidence intervals. We assessed heterogeneity using Cochrane Q and I2statistics and the appropriate p-value. The analysis used RevMan 5.4. GRADE system was used for evidence assessment for each outcome parameter.

RESULTS

This meta-analysis of 11 RCTs (n = 1023 KOA patients) revealed that PRP + HA has substantial effectiveness than PRP alone in reducing OMAC total scores [MD -1.77 (95% CI -2.20 to - 1.34); I2 = 10%, and p < 0.001], VAS scores [MD -4.27 (95% CI -4.96 to - 3.58); I2 = 13%, and p < 0.001], and Lequesne index score [MD -5.48 (95% CI -6.56 to - 4.40); I2 = 16%, and p < 0.001], while increasing IKDC scores [MD -2.10 (95% CI -3.70 to - 0.50); I2 = 9%, and p = 0.01], with low risk of adverse events [RR 0.41 (95% CI 0.35 to 0.48); I2 = 12%, and p < 0.001].

CONCLUSION

This meta-analysis reveals that, for patients with KOA, PRP + HA therapy is safe and yields better outcomes in pain relief and functional improvement compared to PRP monotherapy.

Efficacy of weekly versus daily cholecalciferol for repleting serum vitamin D (25(OH)D) deficiency: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND/RATIONALE

Weekly cholecalciferol can replace daily supplementation to reduce pill burden in patients with complex medication regimens and hypovitaminosis D, but evidence supporting this switch is unclear.

OBJECTIVE

We aimed to determine whether weekly cholecalciferol was superior to daily cholecalciferol to replete patients with hypovitaminosis D.

METHODS

We conducted a systematic review of randomized controlled trials involving participants with baseline hypovitaminosis D (<30 ng/ml) comparing weekly versus daily cholecalciferol dosing and where serum cholecalciferol was measured within 120 days of starting treatment. We searched MEDLINE, CINAHL and EMBASE from inception to 7 May 2024. A random-effects meta-analysis evaluated the odds ratio for repletion of serum vitamin D levels.

FINDINGS

Eight trials involving 542 patients were included in the analysis. Weekly and daily cholecalciferol were not significantly different in correcting hypovitaminosis D (OR = 1.5, 95% CI = 0.3-6.9, p = 0.6, favouring weekly dosing, I2 = 85.3%). A sensitivity analysis excluding otherwise healthy patients had similar findings (OR = 0.8, 95% CI = 0.3-2.1, p = 0.6). Most studies were at risk of bias; the different doses being compared increased the heterogeneity.

CONCLUSIONS

Limited direct evidence supports a switch from daily to weekly cholecalciferol dosing; however, weekly supplementation was not demonstrably worse at repleting levels and decreased a patient's daily pill burden.

Assessment of inverse publication bias in safety outcomes: an empirical analysis

BACKGROUND

The aims of this study were to assess the presence of inverse publication bias (IPB) in adverse events, evaluate the performance of visual examination, and explore the impact of considering effect direction in statistical tests for such assessments.

METHODS

We conducted a cross-sectional study using the SMART Safety, the largest dataset for evidence synthesis of adverse events. The visual assessment was performed using contour-enhanced funnel plots, trim-and-fill funnel plots, and sample-size-based funnel plots. Two authors conducted visual assessments of these plots independently, and their agreements were quantified by the kappa statistics. Additionally, IPB was quantitatively assessed using both the one- and two-sided Egger's and Peters' tests.

RESULTS

In the SMART Safety dataset, we identified 277 main meta-analyses of safety outcomes with at least 10 individual estimates after dropping missing data. We found that about 13.7-16.2% of meta-analyses exhibited IPB according to the one-sided test results. The kappa statistics for the visual assessments roughly ranged from 0.3 to 0.5, indicating fair to moderate agreement. Using the one-sided Egger's test, 57 out of 72 (79.2%) meta-analyses that initially showed significant IPB in the two-sided test changed to non-significant, while the remaining 15 (20.8%) meta-analyses changed from non-significant to significant.

CONCLUSIONS

Our findings provide supporting evidence of IPB in the SMART Safety dataset of adverse events. They also suggest the importance of researchers carefully accounting for the direction of statistical tests for IPB, as well as the challenges of assessing IPB using statistical methods, especially considering that the number of studies is typically small. Qualitative assessments may be a necessary supplement to gain a more comprehensive understanding of IPB.

Clinical efficacy of various resuscitation fluids in the management of sepsis in postoperative surgical and trauma patients: a systematic review and meta--analysis

INTRODUCTION

Fluid resuscitation is the primary sepsis management strategy aimed at reducing mortality and achieving better treatment outcomes in critically hypotensive patients. Still, there are significant ambiguities regarding the most suitable fluid type that would ensure optimization of patient outcomes.

AIM

The aim of this systematic review and meta-analysis was to assess the clinical effectiveness of different resuscitation fluids for sepsis management in critically hypotensive patients.

MATERIALS AND METHODS

A systematic search of 4 electronic databases (PubMed, EMBASE, Scopus, and Cochrane Library) was conducted to identify relevant papers published in peer-reviewed journals since database inception until June 30, 2024. Odds ratios (ORs) with 95% CIs were calculated to evaluate the impact of individual resuscitation fluids on improvements in hemodynamic parameters and all-cause mortality. Heterogeneity was assessed using the Cochran Q, I2 statistic, and the appropriate P value.

RESULTS

Our meta-analysis included 18 randomized controlled trials comparing the efficacy of different resuscitation fluids for sepsis management in 14 469 critically hypotensive patients. We found that Ringer's lactate solution was more effective than saline in reducing mortality (OR, 0.53; 95% CI, 0.41-0.7; χ2= 3.47; degree of freedom [df] = 6; Z = 4.6; I2 = 0%; P <⁠0.001) and improving hemodynamic parameters (OR, 2.64; 95% CI, 2.45-2.86; χ2 = 48.36; df = 6; Z = 24.84; I2 = 18%; P <⁠0.001). However, saline was superior to albumin and hydroxyethyl starch in reaching these end points.

CONCLUSION

We showed that in critically hypotensive septic patients, Ringer's lactate solution reduces all-cause mortality and improves hemodynamic parameters more effectively than saline, hydroxyethyl starch, and albumin solutions.

Methods for assessing inverse publication bias of adverse events

In medical research, publication bias (PB) poses great challenges to the conclusions from systematic reviews and meta-analyses. The majority of efforts in methodological research related to classic PB have focused on examining the potential suppression of studies reporting effects close to the null or statistically non-significant results. Such suppression is common, particularly when the study outcome concerns the effectiveness of a new intervention. On the other hand, attention has recently been drawn to the so-called inverse publication bias (IPB) within the evidence synthesis community. It can occur when assessing adverse events because researchers may favor evidence showing a similar safety profile regarding an adverse event between a new intervention and a control group. In comparison to the classic PB, IPB is much less recognized in the current literature; methods designed for classic PB may be inaccurately applied to address IPB, potentially leading to entirely incorrect conclusions. This article aims to provide a collection of accessible methods to assess IPB for adverse events. Specifically, we discuss the relevance and differences between classic PB and IPB. We also demonstrate visual assessment through contour-enhanced funnel plots tailored to adverse events and popular quantitative methods, including Egger's regression test, Peters' regression test, and the trim-and-fill method for such cases. Three real-world examples are presented to illustrate the bias in various scenarios, and the implementations are illustrated with statistical code. We hope this article offers valuable insights for evaluating IPB in future systematic reviews of adverse events.

Epidemiology and clinical features of hypnic headache: A systematic review and meta-analysis

BACKGROUND

Hypnic headache is a neurological disorder characterized by recurrent headache attacks that occur exclusively during sleep, leading to awakening. Synthesizing the available epidemiological data might inform clinical decision-making.

METHODS

We searched PubMed and Embase for observational studies on hypnic headache published between 1 May 2004, and 22 December 2022. Two investigators independently screened titles, abstracts, and full-text articles. We performed a random-effects meta-analysis with meta-regression to estimate the prevalence of hypnic headache and its clinical features based on epidemiologic data from population-based and clinic-based studies.

RESULTS

Fourteen studies, one population-based and 13 clinic-based, met our eligibility criteria. The population-based study did not identify any people with hypnic headache. From 11 clinic-based studies, the pooled relative frequency of hypnic headache was 0.21% (95%CI, 0.13 to 0.35%; I2 = 87%) in adult patients evaluated for headache. The pooled mean age of onset was 60.5 years, with a slight female predisposition. Hypnic headache was typically bilateral (71%), pressing (73%), of moderate (38%) or severe (44%) pain intensity, and lasted about 115 minutes per attack.

CONCLUSIONS

Our data should be cautiously interpreted due to between-study heterogeneity. The identified clinical presentation of hypnic headache can guide clinical diagnosis, in addition to the International Classification of Headache Disorders.

Association of branched-chain fatty acids with metabolic syndrome: a systematic review and meta-analysis of observational studies

Background: branched-chain fatty acids (BCFAs) have recently emerged as a group of functional fatty acids that are widely distributed in various foodstuffs, including dairy products, ruminant meat products, and fermented foods. Several studies have investigated the differences in the levels of BCFAs among individuals with varying risks of metabolic syndrome (MetS). In this study, we conducted a meta-analysis to explore the relationship between BCFAs and MetS, and to assess the feasibility of BCFAs as potential biomarkers for diagnosing MetS. Methods: in accordance with the PRISMA guidelines, we conducted a systematic literature search on PubMed, Embase, and the Cochrane Library up to March 2023. Both longitudinal and cross-sectional studies were included. The quality of the longitudinal and cross-sectional studies was evaluated using the Newcastle-Ottawa Scale (NOS) and the Agency for Healthcare Research and Quality (AHRQ) criteria, respectively. Heterogeneity detection and sensitivity analysis of the included research literature were carried out using R 4.2.1 software with a random-effects model. Results: Our meta-analysis included 685 participants and revealed a significant negative correlation between the endogenous BCFAs (serum BCFAs and adipose tissue BCFAs) and the risk of developing MetS, with lower BCFA levels found in individuals at a high risk of MetS (WMD: -0.11%, 95% CI: [-0.12, -0.09] %, P < 0.0001). However, there was no difference in fecal BCFAs among different MetS risk groups (SMD: -0.36, 95% CI: [-1.32, 0.61], P = 0.4686). Conclusion: our study provides insights into the relationship between BCFAs and the risk of developing MetS, and lays the groundwork for the development of novel biomarkers for diagnosing MetS in the future.

THE EFFECT DIRECTION SHOULD BE TAKEN INTO ACCOUNT WHEN ASSESSING SMALL-STUDY EFFECTS

OBJECTIVE

Studies with statistically significant results are frequently more likely to be published than those with non-significant results. This phenomenon leads to publication bias or small-study effects and can seriously affect the validity of the conclusion from systematic reviews and meta-analyses. Small-study effects typically appear in a specific direction, depending on whether the outcome of interest is beneficial or harmful, but this direction is rarely taken into account in conventional methods.

METHODS

We propose to use directional tests to assess potential small-study effects. The tests are built on a one-sided testing framework based on the existing Egger's regression test. We performed simulation studies to compare the proposed one-sided regression tests, conventional two-sided regression tests, as well as two other competitive methods (Begg's rank test and the trim-and-fill method). Their performance was measured by type I error rates and statistical power. Three real-world meta-analyses on measurements of infrabony periodontal defects were also used to examine the various methods' performance.

RESULTS

Based on simulation studies, the one-sided tests could have considerably higher statistical power than competing methods, particularly their two-sided counterparts. Their type I error rates were generally controlled well. In the case study of the three real-world meta-analyses, by accounting for the favored direction of effects, the one-sided tests could rule out potential false-positive conclusions about small-study effects. They also are more powerful in assessing small-study effects than the conventional two-sided tests when true small-study effects likely exist.

CONCLUSION

We recommend researchers incorporate the potential favored direction of effects into the assessment of small-study effects.

Selective serotonin reuptake inhibitors and preeclampsia: A quality assessment and meta-analysis

Serotonin modulates vascular, immune, and neurophysiology and is dysregulated in preeclampsia. Despite biological plausibility that selective serotonin reuptake inhibitors (SSRIs) prevent preeclampsia pathophysiology, observational studies have indicated increased risk and providers may be hesitant. The objective of this meta-analysis and quality assessment was to evaluate the evidence linking SSRI use in pregnancy to preeclampsia/gestational hypertension. PubMed was searched through June 5, 2020 manually and using combinations of terms: "preeclampsia", "serotonin", and "SSRI". This review followed MOOSE guidelines. Inclusion criteria were: 1) Observational cohort or population study, 2) exposure defined as SSRI use during pregnancy, 3) cases defined as preeclampsia or gestational hypertension, and 4) human participants. Studies were selected that addressed the hypothesis that gestational SSRI use modulates preeclampsia and/or gestational hypertension risk. Review Manager Web was used to synthesize study findings. Articles were read and scored (Newcastle-Ottawa Quality Assessment Scale) for quality by two independent reviewers. Publication bias was assessed using a funnel plot and the Egger test. Of 179 screened studies, nine were included. The pooled risk ratio (random effects model) was 1.43 (95 % CI: 1.15-1.78, P < 0.001; range 0.96-4.86). Two studies were rated as moderate quality (both with total score of 6); others were high quality. Heterogeneity was high (I2 = 88 %) and funnel asymmetry was significant (p < 0.00001). Despite evidence for increased preeclampsia risk with SSRIs, shared risk factors and other variables are poorly controlled. Depression treatment should not be withheld due to perceived gestational hypertension risk. Mechanistic evidence for serotonin modulation in preeclampsia demonstrates a need for future research.

Effects and duration of exercise-based prehabilitation in surgical therapy of colon and rectal cancer: a systematic review and meta-analysis

PURPOSE

Functional capacity is an independent indicator of morbidity in colon and rectal cancer surgery. This systematic review describes the evaluated and synthesized effects of exercise prehabilitation depending on the duration of interventions on functional and postoperative outcomes in colon and rectal cancer surgery.

METHODS

Three electronic databases (MEDLINE Pubmed, Web of Sciences, and Cochrane Registry) were systematically searched (January 2022) for controlled trials that investigated the effects of prehabilitation prior to colo-rectal cancer resection.

RESULTS

Twenty-three studies were included in this systematic review and 14 in our meta-analyses assessing these outcomes: the 6 min walk distance (6MWD), postoperative overall complications, and length of stay (LOS). We observed a significant improvement in preoperative functional capacity as measured with 6MWD (mean difference: 30.8 m; 95% CI 13.3, 48.3; p = 0.0005) due to prehabilitation. No reductions in LOS (mean difference: - 0.27 days; 95% CI - 0.93, 0.40; p = 0.5) or postoperative overall complications (Odds ratio: 0.84; 95% CI 0.53, 1.31; p = 0.44) were observed. Prehabilitation lasting more than 3 weeks tended to lower overall complications (Odds ratio: 0.66; 95% CI 0.4, 1.1; p = 0.11). However, the prehabilitation time periods differed between colon and rectal carcinoma resections.

CONCLUSION

Prehabilitation while the patient is preparing to undergo surgery for colorectal carcinoma improves functional capacity; and might reduce postoperative overall complications, but does not shorten the LOS. The studies we reviewed differ in target variables, design, and the intervention's time period. Multicenter studies with sufficient statistical power and differentiating between colon and rectal carcinoma are needed to develop implementation strategies in the health care system.

REGISTRATION

PROSPERO CRD42022310532.

Changes of Th17 cells, regulatory T cells, Treg/Th17, IL-17 and IL-10 in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

PURPOSE

The aim of this study was to investigate the changes of Helper T cells 17 (Th17 cells), Regulatory T cells (Treg cells), Treg/Th17, Interleukin-17 (IL-17) and Interleukin-10 (IL-10) in patients with type 2 diabetes mellitus (T2DM).

METHODS

Four electronic resource databases were searched from their inception to 1 August 2021. Case-control studies about changes of Th17 cells, Treg cells, Treg/Th17, IL-17 and IL-10 in patients with T2DM were retrieved. We performed this meta-analysis via RevMan V.5.3 and Stata14.

RESULTS

20 studies with 1242 individuals were included in the meta-analysis. Compared with the controls, the patients with T2DM had significantly increased levels of percentage of Th17 cells (SMD, 1.74; 95% CI, 0.47-3.01; p < 0.001), IL-17 (SMD, 2.17; 95% CI, 0.06-4.28; p < 0.001), IL-10 (SMD, 1.20; 95% CI, 0.81-1.59; p = 0.003), but decreased levels of percentage of Treg cells (SMD, -1.17; 95% CI, -2.22 to -0.13; p < 0.001) and Treg/Th17 ratio (SMD, -4.43; 95% CI, -7.07 to -1.78; p < 0.001). Subgroup analysis showed that percentage of CD4⁺CD25⁺FOXP3⁺ Tregs (SMD, -2.36; 95% CI, -3.19 to -1.52; p = 0.003) in patients was notably lower than controls. While not significant changes were found in the percentage of CD4⁺CD25⁺Tregs (SMD, 0.03; 95% CI, -0.34-0.40; p = 0.63) between patients and controls. For plasma or serum IL-10, a higher plasma IL-10 level (SMD,1.37; 95% CI, 0.92-1.82; p = 0.01) was observed in T2DM. While serum IL-10 (SMD, 0.73; 95% CI, 0.35-1.12; p = 0.79) had no obvious difference between patients and controls. For ELISA or flow cytometry, IL-10 (SMD, 1.2; 95% CI, 0.71-1.70; p = 0.001) was higher in T2DM patients by using detection method of ELISA. Yet IL-10 using flow cytometry and subgroup analysis of IL-17 had no significant differences.

CONCLUSIONS

Adaptive immune system indeed plays an essential role in the process of T2DM. Imbalance between Th17 and Treg triggers pro-inflammatory environment in patients with T2DM.

Endoscopic ultrasound-guided parenchymal liver biopsy: a systematic review and meta-analysis

BACKGROUND

Endoscopic ultrasonography (EUS)-guided liver biopsy is a novel technique to obtain adequate liver samples for diagnosis of liver parenchymal diseases. There are studies that have evaluated the feasibility and safety of EUS-guided parenchymal liver biopsy (EUS-LB), however, factors that can influence specimen quality are yet to be determined. Our aim was to determine the diagnostic accuracy of EUS-LB and evaluate factors associated with specimen quality.

METHODS

We performed a detailed search of PubMed/MEDLINE and Web of Science™ databases to identify studies in which results of EUS-guided liver parenchymal biopsies were reported published up to July 2020. A random effects model was used to estimate pooled values (mean ± SE) for total specimen length (TSL) and complete portal tracts (CPT). Subgroup analyses were applied to find out the procedural factors associated with better specimen quality using Cochran's Q test. A total of 10 meta-analyses were done focusing on international studies. Total of 1326 patients who underwent EUS-LB. EUS-LBs performed for suspicion of parenchymal liver disease. Pooled mean values for TSL and CPT with subgroup analyses.

RESULTS

Twenty-three studies with a total of 1326 patients were included in our meta-analysis. Overall pooled mean TSL and CPT were 45.3 ± 4.6 mm and 15.8 ± 1.5, respectively. In subgroup analysis, core biopsy needles proved to better in terms of CPT than fine-needle aspiration needles (18.4 vs 10.99, p = 0.003). FNB with slow-pull or suction technique provided a similar TSL (44.3 vs 53.9 mm, p = 0.40), however, slow-pull technique was better in terms of CPT (30 vs 14.6, p < 0.001). Heterogeneity was present among the studies. Another limitation is the low number randomized control trials.

CONCLUSION

EUS-guided parenchymal liver biopsy is a good alternative to other methods of liver sampling. Using FNB needles with a slow-pull technique can provide better results.

Synthesis of evidence from zero-events studies: A comparison of one-stage framework methods

In evidence synthesis, dealing with zero-events studies is an important and complicated task that has generated broad discussion. Numerous methods provide valid solutions to synthesizing data from studies with zero-events, either based on a frequentist or a Bayesian framework. Among frequentist frameworks, the one-stage methods have their unique advantages to deal with zero-events studies, especially for double-arm-zero-events. In this article, we give a concise overview of the one-stage frequentist methods. We conducted simulation studies to compare the statistical properties of these methods to the two-stage frequentist method (continuity correction) for meta-analysis with zero-events studies when double-zero-events studies were included. Our simulation studies demonstrated that the generalized estimating equation with unstructured correlation and beta-binomial method had the best performance among the one-stage methods. The random intercepts generalized linear mixed model showed good performance in the absence of obvious between-study variance. Our results also showed that the continuity correction with inverse-variance heterogeneous (IVhet) analytic model based on the two-stage framework had good performance when the between-study variance was obvious and the group size was balanced for included studies. In summary, the one-stage framework has unique advantages to deal with studies with zero events and is not susceptive to group size ratio. It should be considered in future meta-analyses whenever possible.