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We propose alternative discretization schemes for improving the lattice Boltzmann pseudopotential model for incompressible multicomponent systems, with the purpose of modeling the flow of immiscible fluids with a large viscosity ratio. Compared to the original model of Shan-Chen [Phys. Rev. E 47, 1815 (1993)1063-651X10.1103/PhysRevE.47.1815], the present discretization schemes consider: (i) an explicit force term, (ii) a second-order discretization of the stream term, (iii) a moments-based model for the kinetic nonequilibrium distributions, and (iv) a high-order discretization of the spatial derivative terms. To verify the accuracy of the proposed model, the effects of varying the viscosity ratio as well as both fluid's viscosities on spurious currents and capillary number are investigated for the problems dealing with a static bubble, two-component Poiseuille flow, and immiscible fluid-fluid displacement. The resulting algorithm maintains the simplicity of the pseudopotential model while allowing an easy implementation for multicomponent systems. The results of the model herein proposed show improved control of the interface region and interfacial tension, relatively smaller magnitudes of spurious current values with increasing viscosity ratio, and also a significantly wider stability range with respect to the previously best results in the literature.
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This study investigates the natural convection process within open cavities filled with viscoplastic fluid following the Bingham model with solid square conductive blocks uniformly distributed throughout the cavity. The problem is modeled as a two-dimensional laminar in a steady state with the heated surface parallel to the cavity opening and the other adiabatic surfaces. Three geometries are analyzed: the downward-facing cavity, side-facing cavity, and upward-facing cavity. Parametric analysis is performed in terms of Rayleigh number and Bingham number. The solid-fluid thermal conductivity ratio, the number of blocks, the Prandtl number, and the solid volume fraction within the cavity are fixed, with values of 10, 16, 500, and 0.36, respectively. The results are presented in streamlines, isotherms, unyielded regions, dimensionless velocity, dimensionless temperature, and Nusselt number on the heated surface. A comparison with the closed square cavity is performed, and it is noted that the natural convection has a greater magnitude in the open cavity. Rayleigh and Bingham's numbers have opposite effects on heat transfer. Effects of block interference and channeling of flow within the cavity are observed. For a given value of the Bingham number, there is an abrupt transition from the advective to conductive regime inside the cavity and a critical Bingham number (Bnmax) in which unyielded regions fill the entire geometry, i.e., without flow. Finally, average Nusselt number correlations for each geometry and flow, and no-flow diagrams are presented.
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OBJECTIVES: To describe the implementation and 1-year results of a value-based bariatric surgery program in Brazil. METHODS: The study was conducted at a private hospital in São Paulo, Brazil (Hospital Alemão Oswaldo Cruz). A value-based healthcare program was implemented by designing an episode of care for eligible patients and developing a bundled payment model in which a single payment was made for the bariatric surgery covering the preoperative workup and ending 30 days after discharge. Assessment of outcomes included complication rate, hospital length of stay, intensive care admissions, reoperations, readmissions, and visits to the emergency department in the 30-day postoperative period. The results were compared with real-world evidence retrieved from a Brazilian private insurance database containing information on bariatric procedures performed in similar institutions (benchmark group). RESULTS: Eighty-three patients were enrolled in the value-based healthcare program (80.7% women; 18.0% with type 2 diabetes mellitus; 31.0% with high blood pressure). The mean age was 40.9 years, and body mass index was 42.1 kg/m2. The outcomes recorded in the benchmark group versus the value-based healthcare group involved complication rate, 2.6% versus 1.4% (P = 0.69); length of stay, 2.5 versus 2.0 days (P = 0.0001); intensive care admissions, 4.0% versus 1.2% (P = 0.31); emergency care visits, 15.0% versus 6.0% (P = 0.04); and readmissions, 2.3% versus 0 (P = 0.35), with an estimated cost reduction of 7.1%. CONCLUSIONS: These initial results showed favorable surgical and 30-day outcomes, demonstrating the benefits of a value-based approach for the surgical management of obesity and its comorbidities.
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Cirurgia Bariátrica , Obesidade , Adulto , Brasil , Análise Custo-Benefício , Atenção à Saúde , Diabetes Mellitus Tipo 2/epidemiologia , Feminino , Humanos , Masculino , Obesidade/cirurgiaRESUMO
Laparoscopic surgery has become the preferred surgical approach of several colorectal conditions. However, the economic results of this are quite controversial. The degree of adoption of laparoscopic technology, as well as the aptitude of the surgeons, can have an influence not only in the clinical outcomes but also in the total procedure cost. The aim of this study was to evaluate the clinical and economic outcomes of laparoscopic colorectal surgeries, compared to open procedures in Brazil.All patients who underwent elective colorectal surgeries between January 2012 and December 2013 were eligible to the retrospective cohort. The considered follow-up period was within 30 days from the index procedure. The outcomes evaluated were the length of stay, blood transfusion, intensive care unit admission, in-hospital mortality, use of antibiotics, the development of anastomotic leakage, readmission, and the total hospital costs including re-admissions.Two hundred eighty patients, who met the eligibility criteria, were included in the analysis. Patients in the laparoscopic group had a shorter length of stay in comparison with the open group (6.02â±â3.86 vs 9.86â±â16.27, Pâ<â.001). There were no significant differences in other clinical outcomes between the 2 groups. The total costs were similar between the 2 groups, in the multivariate analysis (generalized linear model ratio of means 1.20, Pâ=â.074). The cost predictors were the cancer diagnosis and age.Laparoscopic colorectal surgery presents a 17% decrease in the duration of the hospital stay without increasing the total hospitalization costs. The factors associated with increased hospital costs were age and the diagnosis of cancer.
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Neoplasias Colorretais/cirurgia , Brasil , Estudos de Coortes , Neoplasias Colorretais/economia , Conversão para Cirurgia Aberta , Procedimentos Cirúrgicos do Sistema Digestório , Feminino , Custos de Cuidados de Saúde , Humanos , Laparoscopia , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias , Estudos Retrospectivos , Resultado do TratamentoRESUMO
OBJECTIVES: The number of bariatric procedures has significantly increased in Brazil, especially in the public Unified Health System. The present study describes health outcomes and medication use in obese patients treated in a major hospital that performs publicly funded surgery in Brazil. METHODS: A retrospective, single center study was conducted to collect real-world evidence of health outcomes and medication use in 247 obese patients (female, 82.2%) who underwent open Roux-en-Y gastric bypass. Changes in weight and body mass index (BMI), presence of apnea, hypertension, and type 2 diabetes (T2D), and medication use (hypertension, diabetes, and dyslipidemia) were assessed preoperatively and up to 24 months postoperatively. The mean cost of medications was calculated for the 12-month preoperative and 24-month postoperative periods. RESULTS: During the surgery, the mean age of patients was 43.42 years (standard deviation [SD], 10.9 years), and mean BMI was 46.7 kg/m2 (SD, 6.7 kg/m2). At 24 months, significant declines were noted in weight (mean, -37.6 kg), BMI (mean, -14.3 kg/m2); presence of T2D, hypertension, and apnea (-29.6%, -50.6%, and -20.9%, respectively); and number of patients using medications (-66.67% for diabetes, -41.86% for hypertension, and -55.26% for dyslipidemia). The mean cost of medications (total costs for all medications) decreased by >50% in 12-24 postoperative months compared to that in 12 preoperative months. CONCLUSION: Roux-en-Y gastric bypass successfully reduced weight, BMI, and comorbidities and medication use and cost at 24 months in Brazilian patients treated in the public Unified Health System.
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Cirurgia Bariátrica , Prescrições de Medicamentos/estatística & dados numéricos , Derivação Gástrica/métodos , Laparoscopia , Obesidade Mórbida/cirurgia , Adulto , Índice de Massa Corporal , Brasil , Complicações do Diabetes/tratamento farmacológico , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Dislipidemias/complicações , Dislipidemias/tratamento farmacológico , Feminino , Refluxo Gastroesofágico/complicações , Refluxo Gastroesofágico/tratamento farmacológico , Humanos , Hipertensão/complicações , Hipertensão/tratamento farmacológico , Obesidade Mórbida/complicações , Avaliação de Resultados em Cuidados de Saúde , Estudos Retrospectivos , Resultado do Tratamento , Redução de PesoRESUMO
OBJECTIVES: The number of bariatric procedures has significantly increased in Brazil, especially in the public Unified Health System. The present study describes health outcomes and medication use in obese patients treated in a major hospital that performs publicly funded surgery in Brazil. METHODS: A retrospective, single center study was conducted to collect real-world evidence of health outcomes and medication use in 247 obese patients (female, 82.2%) who underwent open Roux-en-Y gastric bypass. Changes in weight and body mass index (BMI), presence of apnea, hypertension, and type 2 diabetes (T2D), and medication use (hypertension, diabetes, and dyslipidemia) were assessed preoperatively and up to 24 months postoperatively. The mean cost of medications was calculated for the 12-month preoperative and 24-month postoperative periods. RESULTS: During the surgery, the mean age of patients was 43.42 years (standard deviation [SD], 10.9 years), and mean BMI was 46.7 kg/m2 (SD, 6.7 kg/m2). At 24 months, significant declines were noted in weight (mean, -37.6 kg), BMI (mean, -14.3 kg/m2); presence of T2D, hypertension, and apnea (-29.6%, -50.6%, and -20.9%, respectively); and number of patients using medications (-66.67% for diabetes, -41.86% for hypertension, and -55.26% for dyslipidemia). The mean cost of medications (total costs for all medications) decreased by >50% in 12-24 postoperative months compared to that in 12 preoperative months. CONCLUSION: Roux-en-Y gastric bypass successfully reduced weight, BMI, and comorbidities and medication use and cost at 24 months in Brazilian patients treated in the public Unified Health System.
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Humanos , Feminino , Adulto , Prescrições de Medicamentos/estatística & dados numéricos , Obesidade Mórbida/cirurgia , Derivação Gástrica/métodos , Laparoscopia , Cirurgia Bariátrica , Obesidade Mórbida/complicações , Brasil , Redução de Peso , Refluxo Gastroesofágico/complicações , Refluxo Gastroesofágico/tratamento farmacológico , Índice de Massa Corporal , Estudos Retrospectivos , Resultado do Tratamento , Avaliação de Resultados em Cuidados de Saúde , Complicações do Diabetes/tratamento farmacológico , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Dislipidemias/complicações , Dislipidemias/tratamento farmacológico , Hipertensão/complicações , Hipertensão/tratamento farmacológicoRESUMO
BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmia worldwide, with significantly associated hospitalizations. Considering its growing incidence, the AF related economic burden to healthcare systems is increasing. Healthcare expenditures might be substantially reduced after AF radiofrequency ablation (AFRA). OBJECTIVE: To compare resource utilization and costs before and after AFRA in a cohort of patients from the Brazilian private healthcare system. METHODS: We conducted a retrospective cohort study, based on patients' billing information from an administrative database. Eighty-three adult patients who had an AFRA procedure between 2014 and 2015 were included. Healthcare resource utilization related to cardiovascular causes, including ambulatory and hospital care, as well as its costs, were analyzed. A p-value of less than 0.05 was considered statistically significant. RESULTS: Mean follow-up was 14.7 ± 7.1 and 10.7 ± 5.4 months before and after AFRA, respectively. The 1-year AF recurrence-free rate was 83.6%. Before AFRA, median monthly total costs were Brazilian Reais (BRL) 286 (interquartile range [IQR]: 137-766), which decreased by 63.5% (p = 0.001) after the procedure, to BRL 104 (IQR: 57-232). Costs were reduced both in the emergency (by 58.6%, p < 0.001) and outpatient settings (by 56%, p < 0.001); there were no significant differences in the outpatient visits, inpatient elective admissions and elective admission costs before and after AFRA. The monthly median emergency department visits were reduced (p < 0.001). CONCLUSION: In this cohort, overall healthcare costs were reduced by 63.5%. A longer follow-up could be useful to evaluate if long-term cost reduction is maintained.
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Fibrilação Atrial/economia , Fibrilação Atrial/cirurgia , Ablação por Cateter/economia , Custos de Cuidados de Saúde/estatística & dados numéricos , Setor Privado/economia , Adulto , Idoso , Brasil , Comorbidade , Serviços Médicos de Emergência/economia , Feminino , Hospitalização/economia , Humanos , Masculino , Pessoa de Meia-Idade , Valores de Referência , Estudos Retrospectivos , Estatísticas não ParamétricasRESUMO
PURPOSE: Anastomotic leaks (AL) present a significant source of clinical and economic burden on patients undergoing colorectal surgeries. This study was aimed at evaluating the clinical and economic consequences of AL and its risk factors. METHODS: A retrospective cohort study was conducted between 2012 and 2013 based on the billing information of 337 patients who underwent low anterior resection (LAR). The outcomes evaluated were the development of AL, use of antibiotics, 30-day readmission and mortality, and total hospital costs, including readmissions and length of stay (LOS). The risk factors for AL, as well as the relationship between AL and clinical outcomes, were analyzed using multivariable Poisson regression. Generalized linear models (GLM) were employed to evaluate the association between AL and continuous outcomes (LOS and costs). RESULTS: AL was detected in 6.8% of the patients. Emergency surgery (aRR 2.56; 95% CI: 1.15-5.71, p = 0.021), blood transfusion (aRR 4.44; 95% CI: 1.86-10.64, p = 0.001), and cancer diagnosis (aRR 2.51; 95% CI: 1.27-4.98, p = 0.008) were found to be independent predictors of AL. Patients with AL showed higher antibiotic usage (aRR 1.69; 95% CI: 1.37-2.09, p < 0.001), 30-day readmission (aRR 3.34; 95% CI: 1.53-7.32, p = 0.003) and mortality (aRR 13.49; 95% CI: 4.10-44.35, p < 0.001), and longer LOS (39.6 days, as opposed to 7.5 days for patients without AL, p < 0.001). Total hospital costs amounted to R$210,105 for patients with AL in comparison with R$34,270 for patients without AL (p < 0.001). In multivariable GLM, the total hospital costs for AL patients were 4.66 (95% CI: 3.38-6.23, p < 0.001) times higher than those for patients without AL. CONCLUSIONS: AL leads to worse clinical outcomes and increases hospital costs by 4.66 times. The risk factors for AL were found to be emergency surgery, blood transfusion, and cancer diagnosis.
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This study aimed to evaluate the effectiveness of only Roux-en-Y gastric bypass (RYGB) in patients with type 2 diabetes (T2D) and body mass index (BMI) of 30-40 kg/m2. A literature search was performed on MEDLINE, Embase, and Cochrane CENTRAL. The searches were performed in February 2017. English was the target language of the publications. The PICO question was used to determine eligibility for studies to be included: population, patient with BMI 30-40 kg/m2; intervention, RYGB; comparison, control group with medical care alone; and outcome, metabolic outcomes. Only randomized clinical trials (RCT) were selected. The main outcome was T2D remission. Secondary outcomes were metabolic effect of RYGB, such as hypertension and dyslipidemia. A total of five RCTs were included. The studies included a larger proportion of women, and the average time of T2D duration ranged between 6 and 10 years with 43.3% of the patients having a BMI below 35 kg/m2. Despite randomization, the baseline demographics such as age, HbA1c, and duration of diabetes were often less favorable in the surgical group. At the longest follow-up, RYGB significantly improves total and partial type 2 remission, OR 17.48 (95% CI 4.28-71.35) and OR 20.71 (95% CI 5.16-83.12), respectively. HbA1c also reduces at longest follow-up in the surgery group (- 1.83 (95% CI - 2.14; - 1.51)). All these three outcomes revealed high level of evidence according to GRADE evaluation. There is already strong evidence that RYGB improves metabolic outcomes for at least 5 years in patients with class I obesity.
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Diabetes Mellitus Tipo 2/cirurgia , Derivação Gástrica/métodos , Obesidade/cirurgia , Adulto , Índice de Massa Corporal , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/epidemiologia , Feminino , Humanos , Hipertensão/complicações , Hipertensão/epidemiologia , Hipertensão/cirurgia , Masculino , Pessoa de Meia-Idade , Obesidade/complicações , Obesidade/epidemiologia , Redução de PesoRESUMO
BACKGROUND: Bariatric surgery has been available as part of the Brazilian Public Health System for patients with body mass index>40 kg/m2 (or>35 kg/m2 with co-morbidities) since 1999. However, access to surgery is challenging, with eligible patients waiting up to 7 years before surgery. OBJECTIVE: Our objective was to compare costs and effectiveness of different waiting times before surgery versus prompt surgery. SETTINGS: Public practice. METHODS: A Markov microsimulation model compared 5 different strategies: no surgery, prompt surgery, and delaying surgery for 1, 2, 4, and 7 years. Markov tracker variables and states reflected changes in body mass index, type 2 diabetes status (including remission and relapse), and cardiovascular events. Time horizon was 20 years; discount rate, 5%; and the perspective of the Brazilian Public Health System. Effectiveness was calculated as quality adjusted life years. RESULTS: Prompt surgery was the least costly and most effective strategy compared with any delay. Costs increased and effectiveness diminished progressively with the length of delays. Waiting 7 years for surgery was the most expensive and least effective strategy. Prompt surgery maintained dominance in 99.9%, 90.7%, 96.1%, and 94.2% of simulations in probabilistic sensitivity analyses versus 1-, 2-, 4-, and 7-year delays, respectively. Immediate surgery was very cost effective compared with no surgery in the case base. In the scenario with all patients having type 2 diabetes, immediate surgery was dominant to any strategy, including the no surgery group. CONCLUSIONS: Delaying bariatric operations is more expensive and less effective compared with prompt surgery and very cost effective compared with no surgery. Public health systems should pursue strategies to accelerate access to surgery to decrease obesity related complications and mortality of patients, but also to improve cost effectiveness.