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There is a paucity of data that compares the relative complication profiles of laparoscopic vertical sleeve gastrectomy (LVSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) at 5 years.The aim was to compare late complications of LVSG and LRYGB.We updated our previous systematic review and meta-analysis of randomized controlled trials of primary LVSG and LRYGB procedures in adults, to review late (5 years) complication outcomes (PROSPERO 112054). Electronic databases were searched from January 2015 to July 2021 for publications meeting inclusion criteria. The Hartung-Knapp-Sidik-Jonkman random effects model was utilized to estimate weighted mean differences where meta-analysis was possible. Bias and certainty of evidence was assessed using the Cochrane risk of bias tool and Grading of Recommendations, Assessment, Development and Evaluations.Four randomized controlled trials met the inclusion criteria (n=531; LVSG=272, LRYGB=259). No late treatment-related mortality was reported with either procedure. A significant reduction in surgical reoperations (odds ratio: 0.47, 95% confidence interval: 0.27-0.82, P =0.01) and endoscopic interventions (odds ratio: 0.29, 95% confidence interval: 0.12-0.71, P =0.02) were reported at 5 years post-LVSG relative to LRYGB. Reoperations were more frequently performed for reflux management in LVSG and for internal hernia repairs in LRYGB. Complications requiring medical management were common following both procedures. Limitations included few eligible studies for inclusion, and varying definitions of medically managed complications.LRYGB is associated with a higher proportion of surgical and endoscopic interventions at 5 years compared with LVSG. More high-quality, long-term studies are required to further elucidate both surgical and nutritional long-term outcomes post these procedures.

With many different operative techniques in use to reduce the incidence of incisional hernias (IH) following a midline laparotomy, there is no consensus among the clinicians on the efficacy and safety of any particular repair technique. This meta-analysis compares the prophylactic onlay mesh repair (POMR) and primary suture repair (PSR) for the incidence of IH. A meta-analysis and systematic review of MEDLINE, PubMed Central (via PubMed), Embase (via Ovid), SCOPUS, ScienceDirect, Google Scholar, SCI and Cochrane Library databases were undertaken. Seven randomized controlled trials assessing the outcomes of PSR and POMR were analyzed in accordance with the PRISMA statement. The risk of bias was assessed using the Rob2 tool. According to the pooled analysis, POMR significantly reduced the incidence of IH compared to the PSR (OR 5.82 [95% CI 2.69, 12.58] P

Bi-directional Grid Constrained (BGC) Stochastic Processes (BGCSP) become more constrained the further they drift away from the origin or time axis are examined here. As they drift further away from the time axis, then the greater the likelihood of stopping, as if by two hidden reflective barriers. The theory of BGCSP is applied to a trading environment in which long and short trading is available. The stochastic differential equation of the Grid Trading Problem (GTP) is proposed, proved and its solution is simulated to derive new findings that can lead to further research in this area and the reduction of risk in portfolio management.

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.

Background: Laparoscopic vertical sleeve gastrectomy (LVSG) has overtaken the laparoscopic Roux-en-Y gastric bypass (LRYGB) as the most frequently performed bariatric surgical procedure. To date little has been reported on the long-term outcomes of the LVSG procedure comparative to the traditionally favoured LRYGB. We undertook a systematic review and meta-analysis to review the 5-year outcomes of comparing LVSG and LRYGB. We undertook a systematic review and meta-analysis to compare 5-year weight loss outcomes of randomized controlled trials comparing LVSG to LRYGB. Materials and Methods: Searches of electronic databases (PubMed, Embase, CINAHL, Cochrane) were undertaken for randomized controlled trials describing weight loss outcomes in adults at 5 years postoperatively. Where sufficient data was available to undertake meta-analysis, the Hartung-Knapp-Sidik-Jonkman estimation method for random effects model was utilized. The review was registered with PROSPERO and reported following in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Results: Five studies met the inclusion criteria totaling 1028 patients (LVSG=520, LRYGB=508). Moderate but comparable levels of bias were observed within studies. Statistically significant body mass index loss ranged from −11.37 kg/m2 (range: −6.3 to −15.7 kg/m2) in the LVSG group and −12.6 kg/m2 (range: −9.5 to −15.4 kg/m2) for LRYGB at 5 years (P

ObjectiveThe study objective was to examine provider acceptance and genotyping responses to a best practice advisory (BPA) concerning clopidogrel and

The Grid Trading Problem (GTP) of mathematical finance, used in portfolio loss minimization, generalized dynamic hedging and algorithmic trading, is researched by examining the impact of the drawdown and drawup of discrete random walks and of Ito diffusions on the Bi-Directional Grid Constrained (BGC) stochastic process for profit Pt and equity E_t over time. A comprehensive Discrete Difference Equation (DDE) and a continuous Stochastic Differential Equation (SDE) are derived and proved for the GTP. This allows fund managers and traders the ability to better stress test the impact of volatility to reduce risk and generate positive returns. These theorems are then simulated to complement the theoretical models with charts. Not only does this research extend a rich mathematical problem that can be further researched in its own right, but it also extends the applications into the above areas of finance.

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 for the grid trading problem (GTP) of financial markets, especially foreign exchange (FX) markets. As banks and financial institutions have the requirement to hedge their FX exposure, the GTP can help provide a framework for greater automation of the hedging process and help forecast which hedge scenarios to avoid. Two theorems are adapted from GRP to GTP and prove 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. We introduce two absorption barriers, one at zero balance (ruin) and one at a specified profit target. This extends the traditional GRP and the GTP further by deriving both the probability of ruin and the expected number of steps (of reaching a barrier) to better demonstrate that GTP takes longer to reach ruin than GRP. These statistical results have applications into finance such as multivariate dynamic hedging (Noorian, Flower, & Leong, 2016), portfolio risk optimization, and algorithmic loss recovery.

Meta-analysis has become an integral part of evidence-based decision-making processes and is being increasingly used in medical and non-medical disciplines. Aggregate data or summary statistics continue to be the mainstay of meta-analysis and are used by many professional societies to support clinical practice guidelines. Meta-analyses synthesize the summary statistics from independent trials by pooling them to estimate the underlying common effect size. The results represent the highest level of evidence but only if the chosen studies are of high quality and the selection criteria are fully satisfied. It is important to address the issues of defining an explicit and relevant question, exhaustively searching for the totality of evidence, meticulous and unbiased data transfer or extraction, assessment of between study heterogeneity and the use of appropriate statistical methods for estimating summary effect measures. This article reviews the methodology, benefits and drawbacks of performing a meta-analysis.

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 Ψ X t , 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.

Laparoscopic vertical sleeve gastrectomy (LVSG) has overtaken the laparoscopic Roux-en-Y gastric bypass (LRYGB) as the most frequently performed bariatric surgical procedure. To date little has been reported on the long-term outcomes of the LVSG procedure comparative to the traditionally favoured LRYGB. We undertook a systematic review and meta-analysis to review the 5-year outcomes of comparing LVSG and LRYGB. We undertook a systematic review and meta-analysis to compare 5-year weight loss outcomes of randomized controlled trials comparing LVSG to LRYGB.Searches of electronic databases (PubMed, Embase, CINAHL, Cochrane) were undertaken for randomized controlled trials describing weight loss outcomes in adults at 5 years postoperatively. Where sufficient data was available to undertake meta-analysis, the Hartung-Knapp-Sidik-Jonkman estimation method for random effects model was utilized. The review was registered with PROSPERO and reported following in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses.Five studies met the inclusion criteria totaling 1028 patients (LVSG=520, LRYGB=508). Moderate but comparable levels of bias were observed within studies. Statistically significant body mass index loss ranged from -11.37 kg/m (range: -6.3 to -15.7 kg/m) in the LVSG group and -12.6 kg/m (range: -9.5 to -15.4 kg/m) for LRYGB at 5 years (P0.001). Systematic review suggested that LRYGB produced a greater weight loss expressed as percent excess weight and percent excess body mass index loss than LVSG: this was not corroborated in the meta-analysis.Five year weight loss outcomes suggest both LRYGB and LVSG are effective in achieving significant weight loss at 5 years postoperatively, however, differences in reporting parameters limit the ability to reliably compare the outcomes using statistical methods. Furthermore, results may be impacted by large dropout rates and per protocol analysis of the 2 largest included studies. Further long-term studies are required to contradict or validate the results of this meta-analysis.

In the era of evidence-based decision-making, systematic reviews (SRs) are being widely used in many health care policies, government programs, and academic disciplines. SRs are detailed and comprehensive literature review of a specific research topic with a view to identifying, appraising, and synthesizing the research findings from various relevant primary studies. A SR therefore extracts the relevant summary information from the selected studies without bias by strictly adhering to the review procedures and protocols. This paper presents all underlying concepts, stages, steps, and procedures in conducting and publishing SRs. Unlike the findings of narrative reviews, the synthesized results of any SRs are reproducible, not subjective and bias free. However, there are a number of issues related to SRs that directly impact on the quality of the end results. If the selected studies are of high quality, the criteria of the SRs are fully satisfied, and the results constitute the highest level of evidence. It is therefore essential that the end users of SRs are aware of the weaknesses and strengths of the underlying processes and techniques so that they could assess the results in the correct perspective within the context of the research question.

Development and implementation of advanced statistical models for analyzing stochastic dependencies of systemic weather risk can help farmers, agricultural policy-makers and financial agents to address potential risk adaptation strategies and mitigation of threats to the agricultural industry. This study develops copula-based statistical models to provide a better understanding of systemic weather risks with agricultural and weather event data from Australia. In particular, we adopt a C-vine approach to model the joint insurance losses caused by drought events occurring simultaneously across different locations, and consecutively in different growing seasons. This modelling approach is enriched by a clustering analysis process through the multidimensional Kruskal–Shephard scaling method. Daily rainfall data (1889–2012) recorded in sixteen meteorological stations across Australia’s wheat belt spanning different climatic conditions are employed. On a regional scale, droughts occurring in the west are more scattered during the October–December period and for April–June and October–December in the eastern, south-eastern and southern regions. On a national scale, drought events in the east are likely to spread out to the south-east and the south but not to the west. The results also reveal that the drought events in different seasons may not be perfectly correlated. Therefore, we conclude that spatial and temporal diversification strategies are likely to feasibly reduce the systemic weather risk in Australia. In particular, the average risk-reducing effect of the entire insured area across regional, national and temporal scales ranges between 0.62–0.94, 0.48–0.76, and 0.25–0.33, corresponding to 5%- (extreme drought) and 25%-quantiles (moderate drought). The findings suggest that diversifying risks over time is potentially more effective than spatial diversification. The outcomes may also act as an efficient tool for agricultural risk reduction, but simultaneously, it may also provide immensely useful information for suitable pricing of weather index-based insurance products.

Aims and objectives: The aim was to conduct a systematic review and meta-analysis of the randomized evidence to determine the relative merits of perioperative outcomes of laparoscopic-assisted (LARR) versus open rectal resection (ORR) for proven rectal cancer. Materials and methods: A search of the Medline, Embase, Science Citation Index, Current Contents and PubMed databases identified English-language randomized clinical trials comparing LARR and ORR. The meta-analysis was prepared in accordance with the PRISMA statement. Thirteen outcome variables were analyzed. Random effects meta-analyses were performed due to heterogeneity. Results: A total of 14 randomized clinical trials that included 3843 rectal resections (LARR 2096, ORR 1747) were analyzed. The summary point estimates favored LARR for the intraoperative blood loss, commencement of oral intake, first bowel movement, and length of hospital stay. There was significantly longer duration of operating time of 38.29 minutes for the LARR group. Other outcome variables such as total complications, postoperative pain, postoperative ileus, abdominal abscesses, postoperative anastomotic leak, reintervention and postoperative mortality rates were found to have comparable outcomes for both cohorts. Conclusions: LARR was associated with significantly reduced blood loss, quicker resumption of oral intake, earlier return of gastrointestinal function, and shorter length of hospital stay at the expense of significantly longer operating time. Postoperative morbidity and mortality and analgesia requirement for both these groups were comparable. LARR seems to be a safe and effective alternative to ORR; however, it needs to be performed in established colorectal units with experienced laparoscopic surgeons.

An agricultural producer's crop yield and the subsequent farming revenues are affected by many complex factors, including price fluctuations, government policy and climate (e.g., rainfall and temperature) extremes. Geographical diversification is identified as a potential farmer adaptation and decision support tool that could assist producers to reduce unfavourable financial impacts due to the variabilities in crop price and yield, associated with climate variations. There has been limited research performed on the effectiveness of this strategy. This paper proposes a new statistical approach to investigate whether the geographical spread of wheat farm portfolios across three climate broad-acre (i.e., rain-fed) zones could potentially reduce financial risks for producers in the Australian agro-ecological zones. A suite of popular and statistically robust tools applied in the financial sector based on the well-established statistical theories, comprised of the Conditional Value-at-Risk (CVaR) and the joint copula models were employed to evaluate the effectiveness geographical diversification. CVaR is utilised to benchmark the losses (i.e., the downside risk), while the copula function is employed to model the joint distribution among marginal returns (i.e., profit in each zone). The mean-CVaR optimisations indicate that geographical diversification could be a feasible agricultural risk management approach for wheat farm portfolio managers in achieving their optimised expected returns while controlling the risks (i.e., target levels of risk). Further, in this study, the copula-based mean-CVaR model is seen to better simulate extreme losses compared to the conventional multivariate-normal models, which underestimate the minimum risk levels at a given target of expected return. Among the suite of tested copula-based models, the vine copula in this study is found to be a superior in capturing the tail dependencies compared to the other multivariate copula models investigated. The present study provides innovative solutions to agricultural risk management with advanced statistical models using Australia as a case study region, also with broader implications to other regions where farming revenues may be optimized through copula-statistical models. Keywords: Copula models, Portfolio optimisation, Conditional value-at-risk, Agriculture management, Crop decision, Geographical diversification

Twelve large-scale climate drivers are employed to investigate their spatio-temporal influence on the variability of seasonal wheat yield in five major wheat-producing states across Australia using data for the period 1983–2013. Generally, the fluctuations in the Indian Ocean appear to have a dominant effect on the Australian wheat crop in all states except Western Australia, while the impact of oceanic conditions in the Pacific region is much stronger in Queensland. The results show a statistically significant negative correlation between the Indian Ocean Dipole (IOD) and the anomalous wheat yield in the early growing stage of the crop in the eastern and southeastern wheat belt regions. This correlation suggests that the wheat yield can be skillfully forecast 3–6 months ahead, supporting early decision-making in regard to precision agriculture. In this study, we use vine copula models to capture climate-yield dependence structures, including the occurrence of extreme events (i.e., the tail dependences). The co-occurrence of extreme events is likely to enhance the impacts of climate mode and this can be quantified probabilistically through conditional copula-based models. Generally, the developed D-vine quantile regression model provide greater accuracy for the forecasting of wheat yield at given different confidence levels compared to the traditional linear quantile regression (LQR) method. A five-fold cross-validation approach is also used to estimate the out-of-sample accuracy of both copula-statistical forecasting models. These findings provide a comprehensive analysis of the spatio-temporal impacts of different climate mode indices on Australian wheat crops. Improved quantification of the impacts of large-scale climate drivers on the wheat yield can allow a development of suitable planning processes and crop production strategies designed to optimize the yield and agricultural profit.

Vine copulas are employed to explore the influence of multi-synoptic-scale climate drivers – El Nino Southern Oscillation (ENSO) and Inter-decadal Pacific Oscillation (IPO) Tripole Index (TPI) – on spring precipitation forecasting at Agro-ecological Zones (AEZs) of the Australia’s wheat belt. To forecast spring precipitation, significant seasonal lagged correlation of ENSO and TPI with precipitation anomalies in AEZs using data from Australian Water Availability Project (1900–2013) was established. Most of the AEZs exhibit statistically significant dependence of precipitation and climate indices, except for the western AEZs. Bivariate and trivariate copula models were applied to capture single (ENSO) and dual predictor (ENSO & TPI) influence, respectively, on seasonal forecasting. To perform a comprehensive evaluation of the developed copula-statistical models, a total of ten one- and two-parameter bivariate copulas ranging from elliptical to Archimedean families were examined. Stronger upper tail dependence is visible in the bivariate model, suggesting that the influence of ENSO on precipitation forecasting during a La Nina event is more evident than during an El Nino event. In general, while the inclusion of TPI as a synoptic-scale driver into the models leads to a notable reduction in the mean simulated precipitation, it depicts a general improvement in the median values. The forecasting results showed that the trivariate forecasting model can yield a better accuracy than the bivariate model for the east and southeast AEZs. The trivariate forecasting model was found to improve the forecasting during the La Nina and negative TPI. This study ascertains the success of copula-statistical models for investigating the joint behaviour of seasonal precipitation modelled with multiple climate indices. The forecasting information and respective models have significant implications for water resources and crop health management including better ways to adapt and implement viable agricultural solutions in the face of climatic challenges in major agricultural hubs, such as Australia’s wheat belt.

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.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.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; P0.01).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.

Proportion is an appropriate effect size measure when we are interested in the incidence or prevalence of certain disease in a population. Meta-analysis under different statistical models along with subgroup analysis is covered here with illustrative examples.

In the era of evidence-based decision-making systematic reviews and meta-analyses are being widely used in many medical practices, public health departments, government programs, business offices, and academic disciplines including education and psychology.

Skillful probabilistic seasonal rainfall forecasts play a vital role in supporting water resource users, developing agricultural risk-management plans, and improving decision-making processes. This chapter applies a novel statistical copula-based approach to develop a probabilistic seasonal rainfall forecast model using multiple large-scale oceanic and atmospheric climate indices. Here, a d -vine copula is used to forecast the seasonal cumulative rainfall in 16 weather stations across the Australia's Wheatbelt. These stations span different climate conditions recording historical data for the period 1889–2012. The seasonal rainfalls are forecast in different quantile levels using different climate predictor data sets. The corrected Akaike information criterion (AIC)–conditional log-likelihood is then used to screen the most influential covariates to be additively incorporated into the multivariate probabilistic forecast model, resulting in a parsimonious predictive model. The mutually inclusive correlations between El Nino–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) indices and seasonal rainfall are found to be statistically significant. Therefore, using the climate information, skillful rainfall forecasts can be made three to 6 months ahead. The d -vine copula model is found to outperform the traditional quantile regression methods in forecasting rainfall in the median and the upper levels. The information from lagged, concurrent, and combined climate indices is therefore demonstrated to be a potentially useful predictor for forecasting seasonal rainfall in Australia's Wheatbelt region.

Fundamental concepts, definitions, scalculating formulae and interpretations of risks and odds as well as the risk ratio and odds ratio are introduced in this chapter. Fundamental concepts, calculating formulae and interpretations of risks and odds as well as the risk ratio and odds ratio are covered in this chapter. The meta-analytical methods of these two very important and frequently used effect size measures, risk ratio and odds ratio, are covered in Chaps. 4 and 5.

If the outcome variable is continuous and interest is to compare the effects of two interventions (e.g. treatment and control), standardized mean difference may be the appropriate effects size measure.

Meta-analysis is a statistical method used to combine numerical summary results on effect size measures, extracted during the systematic review process from independent studies to synthesize a pooled result.

If the linear association/relationship between two continuous/quantitative outcome variables is of interest then the correlation coefficient is the appropriate effect size measure.

If the difference of prevalence rates of any specific disease for two different populations/groups is of interest then difference of two proportions is the appropriate effect size measure. The difference between two proportions is often called the risk difference (RD).

Odds ratio is an appropriate measure of association between two categorical variables (intervention and outcome). The meta-analysis of odds ratio is covered in this chapter. Meta-analysis under different statistical models along with subgroup analysis and detection of publication bias are also covered.

Mean difference can be used as an effect size measure if the outcome variable has the same unit of measurement for both the treatment/intervention and placebo/control groups. The raw mean difference can be scaled by the inverse variance weight to define weighted mean difference (WMD). Unlike the SMD, the WMD retains the same unit of measurement as the outcome variable.

Starting from this chapter meta-analysis of each of the commonly used effect sizes is covered in seperate chapters. This chapter is devoted to exclusive meta-analysis of risk ratio (also called relative risk) is covered in this chapter. It provides meta-analyses of RR under different statistical models along subgroup analysis and detection of publication bias with illustrative examples.

This book focuses on performing hands-on meta-analysis using MetaXL, a free add-on to MS Excel. The illustrative examples are taken mainly from medical and health sciences studies, but the generic methods can be used to perform meta-analysis on data from any other discipline. The book adopts a step-by-step approach to perform meta-analyses and interpret the results. Stata codes for meta-analyses are also provided. All popularly used meta-analytic methods and models – such as the fixed effect model, random effects model, inverse variance heterogeneity model, and quality effect model – are used to find the confidence interval for the effect size measure of independent primary studies and the pooled study. In addition to the commonly used meta-analytic methods for various effect size measures, the book includes special topics such as meta-regression, dose-response meta-analysis, and publication bias. The main attraction for readers is the book’s simplicity and straightforwardness in conducting actual meta-analysis using MetaXL. Researchers would easily find everything on meta-analysis of any particular effect size in one specific chapter once they could determine the underlying effect measure. Readers will be able to see the results under different models and also will be able to select the correct model to obtain accurate results.

The Northern Potwar Plateau of Pakistan is known for its severe geological features. Many wells have been drilled in the region, but geological correlations in neighboring fields have proven to be challenging. Excessive tectonic activity and faults have resulted in formation repetitions, abnormal in-situ stresses, and variable formation pore and fracture pressures. One such field in the region is MDK field, where the operator was in the process of drilling a second well. Drilling of the 8 ½-in. hole section was in progress at 11,004 ft. (3,354 m) when the Bahadur Khel Salt formation was encountered. Upon drilling further into the formation, the operator encountered severe hole stability issues coupled with lost circulation. While in the salt formation, whenever circulation was stopped and annular pressure losses were eliminated, the drill string would become stuck. Upon resuming circulation, the pumping pressure would rise abruptly. The formation was highly stressed and was exhibiting a creeping behavior. Any reduction in the bottom hole pressure (BHP) would cause the formation to creep into the wellbore. The operator spent a month attempting to drill through the highly stressed plastic salt formation, without success. The oil-based mud system was already weighted up to its maximum, and no other conventional means existed of controlling the creeping salt. The operating company had already spent ~USD 19 million dollars on the well, and was considering abandoning it after a nearby well in the same formation had been abandoned despite four unsuccessful sidetracks. Maintaining a constant bottom hole pressure (CBHP) across the formation at all times was the only way to stabilize the salt formation and lost circulation treatment. Only managed pressure drilling (MPD) could achieve the application of CBHP. An MPD system would enable the operator to compensate for the lack of BHP by applying surface backpressure, thereby maintaining the target pressure across the formation at all times. With the help of the MPD system, the operator also sought to calculate the formation creep rate, so as to evaluate a time window for running in and out of the hole. Besides drilling, the operator also intended to isolate the challenging section with a liner. With proper planning, the MPD system could help to achieve this objective. A full MPD system was deployed to the wellsite and drilling resumed with a CBHP in dynamic and static periods. By CBHP MPD, the operator was able to tag bottom. Drilling and underreaming of the 8 ½-in. hole section resumed and continued until reaching the target depth of 14,745 ft. (4,494 m). After drilling, the 7-in. liner was set and cemented to the target depth using MPD. Applying CBHP MPD enabled the operator to drill through 3,832 ft. (1,168 m) of the hole section and save the well from abandonment. This paper studies the design, execution, and lessons learned when applying MPD on the subject well.

Background:To explore the clinical outcomes, safety and effectiveness of suture cruroplasty versus mesh repair for large hiatal hernias (HHs) by an updated meta-analysis.Material and Methods:Randomized controlled trials evaluating the effects of these 2 treatment modalities were searched from PubMed and other electronic databases between January 1991 and July 2018. The outcome variables analyzed included operating time, complications, recurrence of HH or wrap migration, reoperation, hospital stay and quality of life.Results:Five randomized controlled trials totaling 478 patients (suture=222, mesh=256) were analyzed. For reoperation variable, the odds ratio was significantly 3.26 times higher for the suture group. For recurrence of HH, the odds ratio for the suture group was nonsignificantly 1.65 times higher compared with the mesh group. Comparable effects were noted for all other variables.Conclusions:Mesh repair seems to be superior to suture cruroplasty for large HH repair. Therefore, the routine use of mesh may be advantageous in selected cases.