Impact of Mesh Use on Morbidity Following Ventral Hernia Repair With a Simultaneous Bowel Resection

Objective: To evaluate the impact of mesh use on outcomes following ventral hernia repairs and simultaneous bowel resection. Design: Retrospective review. Setting: Teaching academic hospital. Patients: We studied 177 patients who underwent a ventral hernia repair with a bowel resection between May 1, 1992, and May 30, 2007. A prosthesis was used in 51 repairs (mesh group), while 126 repairs were primary (mesh-free group). Main Outcome Measures: Demographic characteristics, comorbidities, mesh type, bowel resection type (colon vs small bowel), defect size, drain use, and length of hospital stay were compared between groups with Fisher exact test and multivariate analysis. Results: There were no statistically significant differences between patient characteristics and relevant comorbidities. The incidence of postoperative infection (superficial or deep) was 22% in the mesh group vs 5% in the mesh-free group (P = .001). Other complications (fistula, seroma, hematoma, bowel obstruction) occurred in 24% of patients in the mesh group vs 8% of patients in the mesh-free group (P = .009). Focusing on the patients who developed an infection, prosthetic mesh use was the only significant risk factor on multivariate regression analysis, irrespective of drain use, defect size, and type of bowel resection. Conclusions: We recommend caution in using mesh when performing a ventral hernia repair with a simultaneous bowel resection because of significantly increased postoperative infectious complications. Drain use, defect size, and bowel resection type did not influence outcomes

Comparison of techniques for handling missing covariate data within prognostic modelling studies: a simulation study

Background: There is no consensus on the most appropriate approach to handle missing covariate data within prognostic modelling studies. Therefore a simulation study was performed to assess the effects of different missing data techniques on the performance of a prognostic model. Methods: Datasets were generated to resemble the skewed distributions seen in a motivating breast cancer example. Multivariate missing data were imposed on four covariates using four different mechanisms; missing completely at random (MCAR), missing at random (MAR), missing not at random (MNAR) and a combination of all three mechanisms. Five amounts of incomplete cases from 5% to 75% were considered. Complete case analysis (CC), single imputation (SI) and five multiple imputation (MI) techniques available within the R statistical software were investigated: a) data augmentation (DA) approach assuming a multivariate normal distribution, b) DA assuming a general location model, c) regression switching imputation, d) regression switching with predictive mean matching (MICE-PMM) and e) flexible additive imputation models. A Cox proportional hazards model was fitted and appropriate estimates for the regression coefficients and model performance measures were obtained. Results: Performing a CC analysis produced unbiased regression estimates, but inflated standard errors, which affected the significance of the covariates in the model with 25% or more missingness. Using SI, underestimated the variability; resulting in poor coverage even with 10% missingness. Of the MI approaches, applying MICE-PMM produced, in general, the least biased estimates and better coverage for the incomplete covariates and better model performance for all mechanisms. However, this MI approach still produced biased regression coefficient estimates for the incomplete skewed continuous covariates when 50% or more cases had missing data imposed with a MCAR, MAR or combined mechanism. When the missingness depended on the incomplete covariates, i.e. MNAR, estimates were biased with more than 10% incomplete cases for all MI approaches. Conclusion: The results from this simulation study suggest that performing MICE-PMM may be the preferred MI approach provided that less than 50% of the cases have missing data and the missing data are not MNAR

Geographic Variation Within the Military Health System

Background: This study seeks to quantify variation in healthcare utilization and per capita costs using system-defined geographic regions based on enrollee residence within the Military Health System (MHS). Methods: Data for fiscal years 2007 – 2010 were obtained from the Military Health System under a data sharing agreement with the Defense Health Agency (DHA). DHA manages all aspects of the Department of Defense Military Health System, including TRICARE. Adjusted rates were calculated for per capita costs and for two procedures with high interest to the MHS- back surgery and Cesarean sections for TRICARE Prime and Plus enrollees. Coefficients of variation (CoV) and interquartile ranges (IQR) were calculated and analyzed using residence catchment area as the geographic unit. Catchment areas anchored by a Military Treatment Facility (MTF) were compared to catchment areas not anchored by a MTF. Results: Variation, as measured by CoV, was 0.37 for back surgery and 0.13 for C-sections in FY 2010- comparable to rates documented in other healthcare systems. The 2010 CoV (and average cost) for per capita costs was 0.26 ($3,479.51). Procedure rates were generally lower and CoVs higher in regions anchored by a MTF compared with regions not anchored by a MTF, based on both system-wide comparisons and comparisons of neighboring areas. Conclusions: In spite of its centrally managed system and relatively healthy beneficiaries with very robust health benefits, the MHS is not immune to unexplained variation in utilization and cost of healthcare

The increase of the functional entropy of the human brain with age

We use entropy to characterize intrinsic ageing properties of the human brain. Analysis of fMRI data from a large dataset of individuals, using resting state BOLD signals, demonstrated that a functional entropy associated with brain activity increases with age. During an average lifespan, the entropy, which was calculated from a population of individuals, increased by approximately 0.1 bits, due to correlations in BOLD activity becoming more widely distributed. We attribute this to the number of excitatory neurons and the excitatory conductance decreasing with age. Incorporating these properties into a computational model leads to quantitatively similar results to the fMRI data. Our dataset involved males and females and we found significant differences between them. The entropy of males at birth was lower than that of females. However, the entropies of the two sexes increase at different rates, and intersect at approximately 50 years; after this age, males have a larger entropy

Preventing cardiac remodeling: The combination of cell-based therapy and cardiac support therapy preserves left ventricular function in rodent model of myocardial ischemia

ObjectiveCellular and mechanical treatment to prevent heart failure each holds therapeutic promise but together have not been reported yet. The goal of the present study was to determine whether combining a cardiac support device with cell-based therapy could prevent adverse left ventricular remodeling, more than either therapy alone.MethodsThe present study was completed in 2 parts. In the first part, mesenchymal stem cells were isolated from rodent femurs and seeded on a collagen-based scaffold. In the second part, myocardial infarction was induced in 60 rats. The 24 survivors were randomly assigned to 1 of 4 groups: control, stem cell therapy, cardiac support device, and a combination of stem cell therapy and cardiac support device. Left ventricular function was measured with biweekly echocardiography, followed by end-of-life histopathologic analysis at 6 weeks.ResultsAfter myocardial infarction and treatment intervention, the ejection fraction remained preserved (74.9-80.2%) in the combination group at an early point (2 weeks) compared with the control group (66.2-82.8%). By 6 weeks, the combination therapy group had a significantly greater fractional area of change compared with the control group (69.2% ± 6.7% and 49.5% ± 6.1% respectively, P = .03). Also, at 6 weeks, the left ventricular wall thickness was greater in the combination group than in the stem cell therapy alone group (1.79 ± 0.11 and 1.33 ± 0.13, respectively, P = .02).ConclusionsCombining a cardiac support device with stem cell therapy preserves left ventricular function after myocardial infarction, more than either therapy alone. Furthermore, stem cell delivery using a cardiac support device is a novel delivery approach for cell-based therapies

Persistent fluctuations in stride intervals under fractal auditory stimulation

Copyright @ 2014 Marmelat et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Stride sequences of healthy gait are characterized by persistent long-range correlations, which become anti-persistent in the presence of an isochronous metronome. The latter phenomenon is of particular interest because auditory cueing is generally considered to reduce stride variability and may hence be beneficial for stabilizing gait. Complex systems tend to match their correlation structure when synchronizing. In gait training, can one capitalize on this tendency by using a fractal metronome rather than an isochronous one? We examined whether auditory cues with fractal variations in inter-beat intervals yield similar fractal inter-stride interval variability as isochronous auditory cueing in two complementary experiments. In Experiment 1, participants walked on a treadmill while being paced by either an isochronous or a fractal metronome with different variation strengths between beats in order to test whether participants managed to synchronize with a fractal metronome and to determine the necessary amount of variability for participants to switch from anti-persistent to persistent inter-stride intervals. Participants did synchronize with the metronome despite its fractal randomness. The corresponding coefficient of variation of inter-beat intervals was fixed in Experiment 2, in which participants walked on a treadmill while being paced by non-isochronous metronomes with different scaling exponents. As expected, inter-stride intervals showed persistent correlations similar to self-paced walking only when cueing contained persistent correlations. Our results open up a new window to optimize rhythmic auditory cueing for gait stabilization by integrating fractal fluctuations in the inter-beat intervals.Commission of the European Community and the Netherlands Organisation for Scientific Research

Hidden Disunities and Uncanny Resemblances: Connections and Disconnections in the Music of Lera Auerbach and Michael Nyman

Does stylistic appropriation serve to create a sense of unity or disunity, continuity or fragmentation? Taking George Lipsitz's notion of �families of resemblance� and intertextuality's dialogic qualities (as shown in the writings of Mikhail Bakhtin and Julia Kristeva), this article will put forward the argument that certain forms of quotation result in a kind of halfway house�an in-between state�where the text seemingly announces its own independence despite its (inter)dependence on a whole host of other intertexts. Unlike the collage-like, so-called polystylistic compositions of the late 1960s, which also used quotation, an altogether different and more deeply embedded form has developed since then, where the quoted material is integrated to a much greater extent on the surface, only to lay bare its �difference� at a deeper level. Such �hidden discontinuities� will be examined in relation to a single work, Lera Auerbach's Sogno di Stabat Mater (2005/2008), before applying Lipsitz's principle as a case study to Michael Nyman's oeuvre

Testing for Fictive Learning in Decision-Making Under Uncertainty

We conduct two experiments where subjects make a sequence of binary choices between risky and ambiguous binary lotteries. Risky lotteries are defined as lotteries where the relative frequencies of outcomes are known. Ambiguous lotteries are lotteries where the relative frequencies of outcomes are not known or may not exist. The trials in each experiment are divided into three phases: pre-treatment, treatment and post-treatment. The trials in the pre-treatment and post-treatment phases are the same. As such, the trials before and after the treatment phase are dependent, clustered matched-pairs, that we analyze with the alternating logistic regression (ALR) package in SAS. In both experiments, we reveal to each subject the outcomes of her actual and counterfactual choices in the treatment phase. The treatments differ in the complexity of the random process used to generate the relative frequencies of the payoffs of the ambiguous lotteries. In the first experiment, the probabilities can be inferred from the converging sample averages of the observed actual and counterfactual outcomes of the ambiguous lotteries. In the second experiment the sample averages do not converge. If we define fictive learning in an experiment as statistically significant changes in the responses of subjects before and after the treatment phase of an experiment, then we expect fictive learning in the first experiment, but no fictive learning in the second experiment. The surprising finding in this paper is the presence of fictive learning in the second experiment. We attribute this counterintuitive result to apophenia: “seeing meaningful patterns in meaningless or random data.” A refinement of this result is the inference from a subsequent Chi-squared test, that the effects of fictive learning in the first experiment are significantly different from the effects of fictive learning in the second experiment

Racial Disparities in Emergency General Surgery: Do Differences in Outcomes Persist Among Universally Insured Military Patients?

Research Objective: Described as one of the most serious health problems affecting the nation, racial disparities are estimated to account for \u3e83,000 deaths, \u3e$57 billion per year. They have been identified in multiple surgical settings, including differences in outcomes by race among emergency general surgery(EGS) patients. As many minority patients are uninsured, increasing access to care is thought to be a viable solution to mitigate inequities. The objectives of this study were to determine whether racial disparities in 30/90/180day outcomes exist within a universally-insured population of military/civilian-dependent EGS patients and whether differences in outcomes differentially persist in care received at military-vs-civilian hospitals and among sponsors who are enlisted-service members-vs-officers. It also considered longer-term outcomes of care. Study Design: Risk-adjusted survival analyses using Cox proportional-hazards models assessed race-based differences in mortality, major morbidity, and readmission from index-hospital admission (discharge for readmission) through 30/90/180days. Models accounted for hospital clustering and possible biases associated with missing race (reweighted-estimating equations). Sub-analyses considered effects restricted to operative interventions, stratified by 24 EGS-diagnostic categories defined by the American Association for the Surgery of Trauma(AAST), and effect modification related to rank (SES-proxy: officers-vs-enlisted-sponsors) and military-vs-civilian-hospital care. Population Studied: Five years of national TRICARE Prime/Prime-plus data, which provides insurance to active/reserve/retired members of the US Armed Services and dependents, were queried for adults (≥18y) with primary EGS conditions, defined by the AAST. Patients who did not have an index admission between 01/01/2006-01/07/2010 (minimum 180days follow-up) or who were not continuously enrolled in TRICARE for 180days were excluded. Non-surviving patients were retained while they survived. Principal Findings: A total of 101,011 patients were included: 73.5% White, 14.5% Black, 4.4% Asian, 7.7% other. Risk-adjusted analyses reported equivalent-or-better mortality and readmission outcomes among minority patients at 30/90/180days—even when restricted to civilian hospitals where studies suggest that EGS disparities are found. Readmissions within military hospitals were lower among minority patients. Major morbidity was higher among Black versus White patients (HR[95%CI]): 30day-1.23[1.13-1.35], 90day-1.18[1.09-1.28], 180day-1.15[1.07-1.24]—a finding driven by appendiceal disorders (HR:1.69-1.70). No other diagnostic category-based HR was significant. When considered by rank, significant effects were isolated to enlisted-service members. However, given the relatively small number of patients who were (dependents of) officers, it is difficult to determine whether rank-based findings are a result of social determinants or influenced by the limited number of minority patients. Conclusions: The first of its kind to examine racial disparities in longer-term outcomes of EGS care, this longitudinal analysis of military patients demonstrated apparent mitigation of racial disparities within a universally-insured health system when compared to the overall US health system. Efforts to explain findings based on consideration of care provided in military-vs-civilian hospitals, among specific EGS-diagnostic categories, and based on sponsor rank revealed modification of the association between race and outcomes to some extent for all three. Implications for Policy or Practice: The contrast between results for universally-insured military/civilian-dependent patients and reported disparities among all US civilian patients merits consideration. The data speak to the importance of insurance-coverage in the development of disparities interventions nationwide and will help to inform policy within the DoD

Charting the elements of pedagogic frailty

Background: The concept of pedagogic frailty has been proposed as a unifying concept that may help to integrate institutional efforts to enhance teaching improvement within universities by helping to maintain a simultaneous focus on four key areas that are thought to impede development. Purpose: The variation in internal structure of the four dimensions of pedagogic frailty and the links that have been proposed to connect them are explored here through the analysis of interviews with academics working in a variety of disciplinary areas. Methods: The application of concept map-mediated interviews allows us to view the variable connections within and between these dimensions and the personal ways they are conceptualised by academics working across the heterogeneous university context. Results: The data show that academics conceptualise the discourse of teaching in various ways that have implications for the links that may be developed to integrate the elements within the model. Conclusions: Whilst the form and content of the maps representing dimensions of the pedagogic frailty model exhibit considerable variation, it is suggested that factors such as academic resilience and the explicit use of integrative concepts within disciplines may help to overcome some of the vulnerabilities that accompany pedagogic frailty. The data also raises questions about the links between factors that tend to be under individual control and those that tend towards institutional control