Forecast Combinations

We consider combinations of subjective survey forecasts and model-based forecasts from linear and non-linear univariate specifications as well as multivariate factor-augmented models. Empirical results suggest that a simple equal-weighted average of survey forecasts outperform the best model-based forecasts for a majority of macroeconomic variables and forecast horizons. Additional improvements can in some cases be gained by using a simple equal-weighted average of survey and model-based forecasts. We also provide an analysis of the importance of model instability for explaining gains from forecast combination. Analytical and simulation results uncover break scenarios where forecast combinations outperform the best individual forecasting model.Factor Based Forecasts, Non-linear Forecasts, Structural Breaks, Survey Forecasts, Univariate Forecasts.

Forecast combinations

We consider combinations of subjective survey forecasts and model-based forecasts from linear and non-linear univariate specifications as well as multivariate factor-augmented models. Empirical results suggest that a simple equal-weighted average of survey forecasts outperform the best model-based forecasts for a majority of macroeconomic variables and forecast horizons. Additional improvements can in some cases be gained by using a simple equal-weighted average of survey and model-based forecasts. We also provide an analysis of the importance of model instability for explaining gains from forecast combination. Analytical and simulation results uncover break scenarios where forecast combinations outperform the best individual forecasting model

Magnetic Sphincter Augmentation for Gastroesophageal Reflux After Sleeve Gastrectomy: A Systematic Review

This systematic review aims to evaluate the current evidence regarding safety and efficacy of magnetic sphincter augmentation (MSA) for the treatment of gastroesophageal reflux disease (GERD) after laparoscopic sleeve gastrectomy (LSG). Conversion to Roux-en-Y gastric bypass (RYGB) carries the risk of surgical and metabolic complications and may be contraindicated in patients with normalized or near-normalized body mass index. The LINXTM procedure aims to restore LES competency and to repair the crura. We included 109 patients (14 studies) undergoing LINXTM implant after LSG. Median follow-up was 18.9 months (range 0.3–63). Both the GERD-HRQL (38 ± 13 vs. 10 ± 11; p = 0.0078) and daily PPI use (97.4% vs. 25.3%; p < 0.0001) were significantly improved. Overall, 31.8% of the patients experienced device-related adverse events, mainly self-limiting. LINXTM explant for esophageal erosion occurred in 0.9% of the patients

Effect of powered circular stapler in colorectal anastomosis after left-sided colic resection: systematic review and meta-analysis

Purpose: Anastomotic leak (AL) remains the most important complication after left-sided colic anastomoses and technical complications during anastomotic construction are responsible of higher leakage incidence. Powered circular stapler (PCS) in colorectal surgery has been introduced in order to reduce technical errors and post-operative complications due to the manual circular stapler (MCS). Methods: A systematic review and meta-analysis were performed. An electronic systematic search was performed using Web of Science, PubMed, and Embase of studies comparing PCS and MCS. The incidence of AL, anastomotic bleeding (AB), conversion, and reoperation were assessed. PROSPERO Registration Number: CRD42024512644. Results: Five observational studies were eligible for inclusion reporting on 2379 patients. The estimated pooled Risk Ratios for AL and AB rates following PCS were significantly lower than those observed with MCS (0.44 and 0.23, respectively; both with p < 0.01). Conversion and reoperation rate did not show any significant difference: 0.41 (95% CI 0.09–1.88; p = 0.25) and 0.78 (95% CI 0.33–1.84; p = 0.57); respectively. Conclusion: The use of PCS demonstrates a lower incidence of AL and AB compared to MCS but does not exhibit a discernible influence on reintervention or conversion rates. The call for future randomized clinical trials aims to definitively clarify these issues and contribute to further advancements in refining surgical strategies for left-sided colonic resection

Kupffer Cells Hasten Resolution of Liver Immunopathology in Mouse Models of Viral Hepatitis

Kupffer cells (KCs) are widely considered important contributors to liver injury during viral hepatitis due to their pro-inflammatory activity. Herein we utilized hepatitis B virus (HBV)-replication competent transgenic mice and wild-type mice infected with a hepatotropic adenovirus to demonstrate that KCs do not directly induce hepatocellular injury nor do they affect the pathogenic potential of virus-specific CD8 T cells. Instead, KCs limit the severity of liver immunopathology. Mechanistically, our results are most compatible with the hypothesis that KCs contain liver immunopathology by removing apoptotic hepatocytes in a manner largely dependent on scavenger receptors. Apoptotic hepatocytes not readily removed by KCs become secondarily necrotic and release high-mobility group box 1 (HMGB-1) protein, promoting organ infiltration by inflammatory cells, particularly neutrophils. Overall, these results indicate that KCs resolve rather than worsen liver immunopathology

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity > 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI

Infected pancreatic necrosis: outcomes and clinical predictors of mortality. A post hoc analysis of the MANCTRA-1 international study

: The identification of high-risk patients in the early stages of infected pancreatic necrosis (IPN) is critical, because it could help the clinicians to adopt more effective management strategies. We conducted a post hoc analysis of the MANCTRA-1 international study to assess the association between clinical risk factors and mortality among adult patients with IPN. Univariable and multivariable logistic regression models were used to identify prognostic factors of mortality. We identified 247 consecutive patients with IPN hospitalised between January 2019 and December 2020. History of uncontrolled arterial hypertension (p = 0.032; 95% CI 1.135-15.882; aOR 4.245), qSOFA (p = 0.005; 95% CI 1.359-5.879; aOR 2.828), renal failure (p = 0.022; 95% CI 1.138-5.442; aOR 2.489), and haemodynamic failure (p = 0.018; 95% CI 1.184-5.978; aOR 2.661), were identified as independent predictors of mortality in IPN patients. Cholangitis (p = 0.003; 95% CI 1.598-9.930; aOR 3.983), abdominal compartment syndrome (p = 0.032; 95% CI 1.090-6.967; aOR 2.735), and gastrointestinal/intra-abdominal bleeding (p = 0.009; 95% CI 1.286-5.712; aOR 2.710) were independently associated with the risk of mortality. Upfront open surgical necrosectomy was strongly associated with the risk of mortality (p < 0.001; 95% CI 1.912-7.442; aOR 3.772), whereas endoscopic drainage of pancreatic necrosis (p = 0.018; 95% CI 0.138-0.834; aOR 0.339) and enteral nutrition (p = 0.003; 95% CI 0.143-0.716; aOR 0.320) were found as protective factors. Organ failure, acute cholangitis, and upfront open surgical necrosectomy were the most significant predictors of mortality. Our study confirmed that, even in a subgroup of particularly ill patients such as those with IPN, upfront open surgery should be avoided as much as possible. Study protocol registered in ClinicalTrials.Gov (I.D. Number NCT04747990)

Model Uncertainty, Thick Modelling and the Predictability of Stock Returns

Recent financial research has provided evidence on the predictability of asset returns. In this Paper we consider the results contained in Pesaran-Timmerman (1995), which provided evidence on predictability of excess returns in the US stock market over the sample 1959-92. We show that the extension of the sample to the nineties weakens considerably the statistical and economic significance of the predictability of stock returns based on earlier data. We propose an extension of their framework, based on the explicit consideration of model uncertainty under rich parameterizations for the predictive models. We propose a novel methodology to deal with model uncertainty based on ‘thick’ modelling, i.e. considering a multiplicity of predictive models rather than a single predictive model. We show that portfolio allocations based on a thick modeling strategy systematically outperform thin modelling.