Abstract This article examines an improved alternative to the random effects (RE) model for meta-analysis of heterogeneous studies. It is shown that the known issues of underestimation of the ...statistical error and spuriously overconfident estimates with the RE model can be resolved by the use of an estimator under the fixed effect model assumption with a quasi-likelihood based variance structure — the IVhet model. Extensive simulations confirm that this estimator retains a correct coverage probability and a lower observed variance than the RE model estimator, regardless of heterogeneity. When the proposed IVhet method is applied to the controversial meta-analysis of intravenous magnesium for the prevention of mortality after myocardial infarction, the pooled OR is 1.01 (95% CI 0.71–1.46) which not only favors the larger studies but also indicates more uncertainty around the point estimate. In comparison, under the RE model the pooled OR is 0.71 (95% CI 0.57–0.89) which, given the simulation results, reflects underestimation of the statistical error. Given the compelling evidence generated, we recommend that the IVhet model replace both the FE and RE models. To facilitate this, it has been implemented into free meta-analysis software called MetaXL which can be downloaded from www.epigear.com.
Many fungi require specific growth conditions before they can be identified. Direct environmental DNA sequencing is advantageous, although for some taxa, specific primers need to be used for ...successful amplification of molecular markers. The internal transcribed spacer region is the preferred DNA barcode for fungi. However, inter- and intra-specific distances in ITS sequences highly vary among some fungal groups; consequently, it is not a solely reliable tool for species delineation. Ampelomyces, mycoparasites of the fungal phytopathogen order Erysiphales, can have ITS genetic differences up to 15%; this may lead to misidentification with other closely related unknown fungi. Indeed, Ampelomyces were initially misidentified as other pycnidial mycoparasites, but subsequent research showed that they differ in pycnidia morphology and culture characteristics. We investigated whether the ITS2 nucleotide content and secondary structure was different between Ampelomyces ITS2 sequences and those unrelated to this genus. To this end, we retrieved all ITS sequences referred to as Ampelomyces from the GenBank database. This analysis revealed that fungal ITS environmental DNA sequences are still being deposited in the database under the name Ampelomyces, but they do not belong to this genus. We also detected variations in the conserved hybridization model of the ITS2 proximal 5.8S and 28S stem from two Ampelomyces strains. Moreover, we suggested for the first time that pseudogenes form in the ITS region of this mycoparasite. A phylogenetic analysis based on ITS2 sequences-structures grouped the environmental sequences of putative Ampelomyces into a different clade from the Ampelomyces-containing clades. Indeed, when conducting ITS2 analysis, resolution of genetic distances between Ampelomyces and those putative Ampelomyces improved. Each clade represented a distinct consensus ITS2 S2, which suggested that different pre-ribosomal RNA (pre-rRNA) processes occur across different lineages. This study recommends the use of ITS2 S2s as an important tool to analyse environmental sequencing and unveiling the underlying evolutionary processes.
Background
The prevalence of type 2 diabetes is growing in both developed and developing countries and is strongly linked with the prevalence of obesity. Bariatric surgical procedures such as ...laparoscopic vertical sleeve gastrectomy (LVSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) are increasingly being utilized to manage related comorbid chronic conditions, including type 2 diabetes.
Methods
A systematic review of randomized controlled trials (RCTs) was undertaken using the PRISMA guidelines to investigate the postoperative impact on diabetes resolution following LVSG versus LRYGB.
Results
Seven RCTs involving a total of 732 patients (LVSG
n
= 365, LRYGB
n
= 367) met inclusion criteria. Significant diabetes resolution or improvement was reported with both procedures across all time points. Similarly, measures of glycemic control (HbA1C and fasting blood glucose levels) improved with both procedures, with earlier improvements noted in LRYGB that stabilized and did not differ from LVSG at 12 months postoperatively. Early improvements in measures of insulin resistance in both procedures were also noted in the studies that investigated this.
Conclusions
This systematic review of RCTs suggests that both LVSG and LRYGB are effective in resolving or improving preoperative type 2 diabetes in obese patients during the reported 3- to 5-year follow-up periods. However, further studies are required before longer-term outcomes can be elucidated. Areas identified that need to be addressed for future studies on this topic include longer follow-up periods, standardized definitions and time point for reporting, and financial analysis of outcomes obtained between surgical procedures to better inform procedure selection.
Bi-Directional Grid Constrained (BGC) trading strategies have never been studied academically until now, are relatively new in the world of financial markets and have the ability to out-perform many ...other trading algorithms in the short term but will almost surely ruin an investment account in the long term. Whilst the Gambler’s Ruin Problem (GRP) is based on martingales and the established probability theory proves that the GRP is a doomed strategy, this research details how the semimartingale framework is required to solve the grid trading problem (GTP), i.e. a form of BGC financial markets strategies, and how it can deliver greater return on investment (ROI) for the same level of risk. A novel theorem of GTP is derived, proving that grid trading, whilst still subject to the risk of ruin, has the ability to generate significantly more profitable returns in the short term. This is also supported by extensive simulation and distributional analysis. These results not only can be studied within mathematics and statistics in their own right, but also have applications into finance such as multivariate dynamic hedging, investment funds, trading, portfolio risk optimization and algorithmic loss recovery. In today’s uncertain and volatile times, investment returns are between 2%-5% per annum, barely keeping up with inflation, putting people’s retirement at risk. BGC and GTP are thus a rich source of innovation potential for improved trading and investing.
Acknowledgement(s)Aldo Taranto was supported by an Australian Government Research Training Program (RTP) Scholarship. The authors would like to thank A/Prof. Ravinesh C. Deo and A/Prof. Ron Addie of the University of Southern Queensland for their invaluable advice on refining this paper.
Bidirectional Grid Constrained (BGC) stochastic processes (BGCSPs) are constrained Itô diffusions with the property that the further they drift away from the origin, the more the resistance to ...movement in that direction they undergo. The underlying characteristics of the BGC parameter ΨXt,t are investigated by examining its geometric properties. The most appropriate convex form for Ψ, that is, the parabolic cylinder is identified after extensive simulation of various possible forms. The formula for the resulting hidden reflective barrier(s) is determined by comparing it with the simpler Ornstein–Uhlenbeck process (OUP). Applications of BGCSP arise when a series of semipermeable barriers are present, such as regulating interest rates and chemical reactions under concentration gradients, which gives rise to two hidden reflective barriers.
Objectives
The aim was to conduct a meta-analysis of the randomized evidence to determine the relative merits of laparoscopic assisted (LADG) and open (ODG) distal gastrectomy for proven gastric ...cancer.
Data sources and review methods
A search of the Medline, Embase, Science Citation Index, Current Contents, and PubMed databases identified all randomized clinical trials (RCTs) that compared LADG and OGD and were published in the English language between January 1990 and the end of June 2007. The meta-analysis was prepared in accordance with the Quality of Reporting of Meta-analyses (QUOROM) statement. The eight outcome variables analysed were operating time, blood loss, retrieval of lymph nodes, oral intake, hospital stay, postoperative complications, tumor recurrence, and mortality. Random effects meta-analyses were performed using odds ratios (OR) and weighted mean differences (WMD).
Results
Four trials were considered suitable for meta-analysis. A total of 82 patients underwent LADG and 80 had ODG. For only one of the eight outcomes, the summary point estimates favoured LADG over ODG; there was a significant reduction of 104.26 ml in intraoperative blood loss for LADG (WMD, −104.26, 95% confidence interval (CI) −189.01 to −19.51;
p
= 0.0159). There was however a 83.08 min longer duration of operating time for the LADG group compared with the ODG group (WMD 83.08, 95% CI 40.53 to 125.64;
p
= 0.0001) and significant reduction in lymph nodes harvesting of 4.34 lymph nodes in the LADG group (WMD −4.3, 95% CI −6.66 to −2.02;
p
= 0.0002). Other outcome variables such as time to commencement of oral intake (WMD −0.97, 95% CI −2.47 to 0.54;
p
= 0.2068), duration of hospital stay (WMD −3.32, 95% CI −7.69 to 1.05;
p
= 0.1365), rate of complications (OR 0.66, 95% CI 0.27 to 1.60;
p
= 0.3530), mortality rates (OR 0.94, 95% CI 0.21 to 4.19;
p
= 0.9363), and tumor recurrence (OR 1.08, 95% CI 0.42 to 2.79;
p
= 0.8806) were not found to be statistically significant for either group. However, for commencement of oral intake, duration of hospital stay, and complication rate, the trend was in favor of LADG.
Conclusion
LADG was associated with a significantly reduced rate of intraoperative blood loss, at the expense of significantly longer operating time and significantly reduced lymph node retrieval compared to its open counterpart. Mortality and tumor recurrence rates were similar between the two groups. Furthermore, time to commencement of oral intake, postprocedural discharge from hospital, and perioperative complication rate, although not significantly different between the two groups, did suggest a positive trend toward LADG. Based on this meta-analysis, the authors cannot recommend the routine use of LADG over ODG for the treatment of distal gastric cancer. However, significant limitations exist in the interpretation of this data due to the limited number of published randomised control trials, the small sample sizes to date, and the limited duration of follow up. Further large multicentre randomized controlled trials are required to delineate significantly quantifiable differences between the two groups.
To conduct a meta-analysis of randomized controlled trials evaluating the efficacy and drawbacks of limited (D1) versus extended lymphadenectomy (D2) for proven gastric adenocarcinoma.
A search of ...Cochrane, Medline, PubMed, Embase, Science Citation Index and Current Contents electronic databases identified randomized controlled trials published in the English language between 1980 and 2008 comparing the outcomes of D1 versus D2 gastrectomy for gastric adenocarcinoma. The meta-analysis was prepared in accordance with the Preferred Reporting Items for Systematic reviews and Meta-analyses statement. The 6 outcome variables analyzed included length of hospital stay; overall complication rate; anastomotic leak rate; reoperation rate; 30-day mortality rate and 5-year survival rate. Random effects meta-analyses were performed using odds ratios (OR) and weighted mean differences (WMD).
Six trials totaling 1876 patients (D1 = 946, D2 = 930) were analyzed. In 5 of the 6 outcomes the summary point estimates favored D1 over D2 group with a statistically significant reduction of (i) 6.37 days reduction in hospital stay (WMD -6.37, confidence interval CI -10.66, -2.08, P = 0.0036); (ii) 58% reduction in relative odds of developing postoperative complications (OR 0.42, CI 0.27, 0.66, P = 0.0002); (iii) 60% reduction in anastomotic breakdown (OR 0.40, CI 0.25, 0.63, P = 0.0001); (iv) 67% reduction in reoperation rate (OR 0.33, CI 0.15, 0.72, P = 0.006); and (v) 41% reduction in 30-day mortality rate (OR 0.59, CI 0.40, 0.85, P = 0.0054). Lastly there was no significant difference in the 5-year survival (OR 0.97, CI 0.78, 1.20, P = 0.7662) between D1 and D2 gastrectomy patients.
On the basis of this meta-analysis we conclude that D1 gastrectomy is associated with significant fewer anastomotic leaks, postoperative complication rate, reoperation rate, decreased length of hospital stay and 30-day mortality rate. Finally, the 5-year survival in D1 gastrectomy patients was similar to the D2 cohort.
AIMS AND OBJECTIVES:Laparoscopic Heller myotomy (LHM) is the preferred surgical method for treating achalasia. However, peroral endoscopic myotomy (POEM) is providing good short-term results. The ...objective of this systematic review and meta-analysis was to compare the safety and efficacy of LHM and POEM.
MATERIALS AND METHODS:A search of PubMed, Cochrane database, Medline, Embase, Science Citation Index, and current contents for English-language articles comparing LHM and POEM between 2007 and 2016 was performed. Variables analyzed included prior endoscopic treatment, prior medical treatment, prior Heller myotomy, operative time, overall complications rate, postoperative gastroesophageal reflux disease (GERD), length of hospital stay, postoperative pain score, and long-term GERD.
RESULTS:Seven trials consisting of 483 (LHM=250, POEM=233) patients were analyzed. Preoperative variables, for example, prior endoscopic treatment odds ratio (OR), 1.32; 95% confidence interval (CI), 0.23-4.61; P=0.96, prior medical treatment weighted mean difference (WMD), 1.22; 95% CI, 0.52-2.88; P=0.65, and prior Heller myotomy (WMD, 0.47; 95% CI, 0.13-1.67; P=0.25) were comparable. Operative time was 26.28 minutes, nonsignificantly longer for LHM (WMD, 26.28; 95% CI, −11.20 to 63.70; P=0.17). There was a comparable overall complication rate (OR, 1.25; 95% CI, 0.56-2.77; P=0.59), postoperative GERD rate (OR, 1.27; 95% CI, 0.70-2.30; P=0.44), length of hospital stay (WMD, 0.30; 95% CI, −0.24 to 0.85; P=0.28), postoperative pain score (WMD, −0.26; 95% CI, −1.58 to 1.06; P=0.70), and long-term GERD (WMD, 1.06; 95% CI, 0.27-4.1; P=0.08) for both procedures. There was a significantly higher short-term clinical treatment failure rate for LHM (OR, 9.82; 95% CI, 2.06-46.80; P<0.01).
CONCLUSIONS:POEM compares favorably to LHM for achalasia treatment in short-term perioperative outcomes. However, there was a significantly higher clinical treatment failure rate for LHM on short-term postoperative follow-up. Presently long-term postoperative follow-up data for POEM beyond 1 year are unavailable and eagerly awaited.
The aim of this study was to conduct a meta-analysis of randomized evidence to determine the relative merits of laparoscopic anti-reflux surgery (LARS) and open anti-reflux surgery (OARS) for proven ...gastro-esophageal reflux disease (GERD).
A search of the Medline, Embase, Science Citation Index, Current Contents, and PubMed databases identified all randomized clinical trials that compared LARS and OARS and that were published in the English language between 1990 and 2007. A meta-analysis was carried out in accordance with the QUOROM (Quality of Reporting of Meta-Analyses) statement. The six outcome variables analyzed were operating time, hospital stay, return to normal activity, perioperative complications, treatment failure, and requirement for further surgery. Random-effects meta-analyses were carried out using odds ratios (ORs) and weighted mean differences (WMDs).
Twelve trials were considered suitable for the meta-analysis. A total of 503 patients underwent OARS and 533 had LARS. For three of the six outcomes, the summary point estimates favored LARS over OARS. There was a significant reduction of 2.68 days in the duration of hospital stay for the LARS group compared with that for the OARS group (WMD: -2.68, 95% confidence interval (CI): -3.54 to -1.81; P<0.0001), a significant reduction of 7.75 days in return to normal activity for the LARS group compared with that for the OARS group (WMD: -7.75, 95% CI: -14.37 to -1.14; P=0.0216), and finally, there was a statistically significant reduction of 65% in the relative odds of complication rates for the LARS group compared with that for the OARS group (OR: 0.35, 95% CI: 0.16-0.75; P=0.0072). The duration of operating time was significantly longer (39.02 min) in the LARS group (WMD: 39.02, 95% CI: 17.99-60.05; P=0.0003). Treatment failure rates were comparable between the two groups (OR: 1.39, 95% CI: 0.71-2.72; P=0.3423). Despite this, the requirement for further surgery was significantly higher in the LARS group (OR: 1.79, 95% CI: 1.00-3.22; P=0.05).
On the basis of this meta-analysis, the authors conclude that LARS is an effective and safe alternative to OARS for the treatment of proven GERD. LARS enables a faster convalescence and return to productive activity, with a reduced risk of complications and a similar treatment outcome, than an open approach. However, there is a significantly higher rate of re-operation (79%) in the LARS group.
Limitations to accessing delivery care services increase the risks of adverse outcomes during pregnancy and delivery for all pregnant women, particularly among adolescents in LMICs. In order to ...inform adolescent-specific delivery care initiatives and coverage, we conducted a comprehensive analysis of trends, projections and inequalities in coverage of delivery care services among adolescents at national, urban-rural and socio-economic levels in LMICs.
Using 224 nationally representative cross-sectional survey data between 2000 and 2019, we estimated the coverage of institutional delivery (INSD) and skilled birth attendants (SBA). Bayesian hierarchical regression models were used to estimate trends, projections and determinants of INSD and SBA.
Coverage of delivery care services among adolescents increased substantially at the national level, as well as in both urban and rural areas in most countries between 2000 and 2018. Of the 54 LMICs, 24 countries reached 80% coverage of both INSD and SBA in 2018, and predictions for 40 countries are set to exceed 80% by 2030. The trends in coverage of INSD and SBA of adult mothers mostly align with those for adolescent mothers. Our findings show that urban-rural and wealth-based inequalities to delivery care remain persistent by 2030. In 2018, urban settings across 54 countries had higher rates of coverage exceeding 80% compared to rural for both INSD (45 urban, 16 rural) and SBA (50 urban, 19 rural). Several factors such as household head age ≥ 46 years, household head being female, access to mass media, lower parity, higher education, higher ANC visits and higher socio-economic status could increase the coverage of INSD and SBA among adolescents and adult women.
More than three-quarters of the LMICs are predicted to achieve 80% coverage of INSD and SBA among adolescent mothers in 2030, although with sustained inequalities.
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