Guidelines for selecting among different types of bootstraps

ABSTRACT

Background: The bootstrap has become very popular in health economics. Its success lies in the ease of estimating sampling distribution, standard error and confidence intervals with few or no assumptions about the distribution of the underlying population.

Objective: The purpose of this paper is three-fold: (1) to provide an overview of four common bootstrap techniques for readers who have little or no statistical background; (2) to suggest a guideline for selecting the most applicable bootstrap technique for your data; and (3) to connect guidelines with a real world example, to illustrate how different bootstraps behave in one model, or in different models.

Results: The assumptions of homoscedasticity and normality are key to selecting the best bootstrapping technique. These assumptions should be tested before applying any bootstrapping technique. If homoscedasticity and normality hold, then parametric bootstrapping is consistent and efficient. Paired and wild bootstrapping are consistent under heteroscedasticity and non-normality assumptions.

Conclusion: Selecting the correct type of bootstrapping is crucial for arriving at efficient estimators. Our example illustrates that if we selected an inconsistent bootstrapping technique, results could be misleading. An insignificant effect of controller treatment on total health expenditures among asthma patients would have been found significant and negative by an improperly chosen bootstrapping technique, regardless of the type of model chosen.     

A prediction model for treatment decisions in high-grade extremity soft-tissue sarcomas: Personalised sarcoma care (PERSARC)

BackgroundTo support shared decision-making, we developed the first prediction model for patients with primary soft-tissue sarcomas of the extremities (ESTS) which takes into account treatment modalities, including applied radiotherapy (RT) and achieved surgical margins. The PERsonalised SARcoma Care (PERSARC) model, predicts overall survival (OS) and the probability of local recurrence (LR) at 3, 5 and 10 years.AimDevelopment and validation, by internal validation, of the PERSARC prediction model.MethodsThe cohort used to develop the model consists of 766 ESTS patients who underwent surgery, between 2000 and 2014, at five specialised international sarcoma centres. To assess the effect of prognostic factors on OS and on the cumulative incidence of LR (CILR), a multivariate Cox proportional hazard regression and the Fine and Gray model were estimated. Predictive performance was investigated by using internal cross validation (CV) and calibration. The discriminative ability of the model was determined with the C-index.ResultsMultivariate Cox regression revealed that age and tumour size had a significant effect on OS. More importantly, patients who received RT showed better outcomes, in terms of OS and CILR, than those treated with surgery alone. Internal validation of the model showed good calibration and discrimination, with a C-index of 0.677 and 0.696 for OS and CILR, respectively.ConclusionsThe PERSARC model is the first to incorporate known clinical risk factors with the use of different treatments and surgical outcome measures. The developed model is internally validated to provide a reliable prediction of post-operative OS and CILR for patients with primary high-grade ESTS.Level of significancelevel III.     

American Adult Use of Complementary and Alternative Medicine

Editor's Note: In 2004, a study of usage of complementary and alternative medicine among 31,000 American adults revealed that 36% of the population now uses CAM. CAM is defined and usage patterns are described. The survey instrument was developed by the National Center for Complementary and Alternative Medicine and the Center for Disease Control and Prevention National Center for Health Statistics.     

我院药品不良反应84例分析

目的：了解医院药品不良反应（ADR）发生特点及相关因素,促进临床合理用药。方法采取回顾性分析方式,对医院2009年1月_2013年12月上报的84例 ADR 病例进行分类、统计。结果 ADR 病例中,女性患者较多,占总例数的52,38％;抗感染用药占总例数的51,19％;静脉滴注占总例数的89,29％;皮肤及其附件损害为主,其次为全身性损害。结论加强临床用药的合理性,发现 ADR 并及时处理,保证患者用药安全。     

The current state of chronic dialysis treatment in Japan (as of December 31, 2000)

The annual statistical survey conducted at the end of 2000 by the Japanese Society for Dialysis Therapy collected responses from 3358 (99.94%) of 3360 institutions. Japan's total dialysis patient population at the end of the year 2000, as identified by this survey, was 206,134, an increase of 8921 (4.5%) over 1999. This translates to 1624.1 patients per million population. The annual crude mortality rate was 9.4% for the period starting at the end of the year 1999 and ending at the end of the year 2000. The mean patient age at the initiation of dialysis treatment was 63.8 (+/- 13.9; +/- SD) years; the mean age of the overall dialysis patient population was 61.2 years (+/- 13.3). Both these mean ages, which had been increasing since 1983, again continued to increase. Among the primary diagnosis, the prevalence of diabetic nephropathy had continued to increase again since 1999, to 36.6%, whereas that of chronic glomerulonephritis had continued to decline, down to 32.5%, during the same one-year period since the 1999 survey. The 2000 years-end survey incorporated the following additional variables for the first time: usage of oral antihypertensives, pre- and post-dialysis systolic and diastolic blood pressures, serum HDL cholesterol level, types and dosage of oral Vitamin D analogs administered, dosage of oral calcium carbonate administered, history of intervention for peripheral vascular disease (bypass surgery, synthetic graft replacement, stenting), history of coronary artery bypass grafting (CABG), history of percutaneous transluminal coronary angioplasty (PTCA), whether stenting had been previously performed for the treatment of ischemic heart disease, number of cigarettes smoked, the type of vascular access used at the initiation of dialysis, and the year and month the vascular access was created. The survey results indicate that 60.9% of the total dialysis patient population was using oral antihypertensives. The patients' mean serum HDL cholesterol level was 47.65 +/- 18.47 mg/dL, showing positive correlation with serum albumin level and reverse correlation with body mass index. 1.6% of all dialysis patients had previously undergone amputation, and 0.7% had a history of bypass surgery for peripheral vascular disorder. 4.5% of hemodialysis patients had a history of cardiac infarction, 1.6% had previously undergone CABG, and 2.8%, PTCA. At the time the survey was conducted, 2.0% of all dialysis patients were undergoing oral Vitamin D analog pulse therapy, and 6% were undergoing intravenous Vitamin D analog pulse therapy. A history of amputation, myocardial infarction, cerebral infarction, and cerebral bleeding were identified as high-risk factors of vital prognosis. Additionally, high mortality risk was associated with the following: glutamic-pyruvic transaminase levels exceeding 20 IU/L; positive HCV antibody status; comorbid conditions such as hepatic cell carcinoma and liver cirrhosis; platelet counts below 100,000/mL or equal to or greater than 200,000/mL; C-reactive protein levels of 0.2 mg/dL and higher, leukocyte counts of less than 3000/mL or equal to or greater than 8000/mL; and body mass index of below 22 kg/m2, as well as total serum cholesterol levels of below 160 mg/dL or equal to or greater than 260 mg/dL.     

Adherence to the Dietary Approaches to Stop Hypertension (DASH) diet is associated with low levels of insulin resistance among heart failure patients

Background and aimsHeart failure (HF) patients are at risk of developing type 2 diabetes. This study examined the association between adherence to the Dietary Approaches to Stop Hypertension (DASH) diet and insulin resistance among U.S. adults with HF.Methods and resultsUsing data from National Health and Nutrition Examination Survey 1999–2016 cycles, we included 348 individuals aged 20+ years with HF and no history of diabetes. DASH diet adherence index quartile 1 indicated the lowest and quartile 4 indicated the highest adherence. The highest level of insulin resistance was defined by the upper tertile of the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR). Associations between level of insulin resistance and DASH diet adherence and its linear trends were examined using logistic regressions. Trend analyses showed that participants in upper DASH diet adherence index quartiles were more likely older, female, non-Hispanic White, of normal weight, and had lower levels of fasting insulin than those in lower quartiles. Median values of HOMA-IR from lowest to highest DASH diet adherence index quartiles were 3.1 (interquartile range, 1.8–5.5), 2.9 (1.7–5.6), 2.1 (1.1–3.7), and 2.1 (1.3–3.5). Multivariable logistic analyses indicated that participants with the highest compared to the lowest DASH adherence showed 77.1% lower odds of having the highest level of insulin resistance (0.229, 95% confidence interval: 0.073–0.716; p = 0.017 for linear trend).ConclusionGood adherence to the DASH diet was associated with lower insulin resistance among community-dwelling HF patients. Heart healthy dietary patterns likely protect HF patients from developing type 2 diabetes.     

The Survey of Birth Defects Rate Based on Birth Registration System

Background:To investigate the surveillance trend of birth defects,incidence,distribution,occurrence regularity,and their relevant factors in Xi'an City in the last 10 years for proposing control measur...     

The Heart Failure Association Atlas: rationale,objectives, and methods

Heart failure (HF) constitutes the growing cardiovascular burden and the major public health issue, but comprehensive statistics on HF epidemiology and related management in Europe are missing. The Heart Failure Association (HFA) Atlas has been initiated in 2016 in order to close this gap, representing the continuity directly rooted in the European Society of Cardiology (ESC) Atlas of Cardiology. The major aim of the HFA Atlas is to establish a contemporary dataset on HF epidemiology, resources and reimbursement policies for HF management, organization of the National Heart Failure Societies (NHFS) and their major activities, including education and HF awareness. These data are gathered in collaboration with the network of NHFS of the ESC member and ESC affiliated countries. The dataset will be continuously improved and advanced based on the experience and enhanced understanding of data collection in the forthcoming years. This will enable revealing trends, disparities and gaps in knowledge on epidemiology and management of HF. Such data are highly needed by the clinicians of different specialties (aside from cardiologists and cardiac surgeons), researchers, healthcare policy makers, as well as HF patients and their caregivers. It will also allow to map the snapshot of realities in HF care, as well as to provide insights for evidence‐based health care policy in contemporary management of HF. Such data will support the ESC/HFA efforts to improve HF management ant outcomes through stronger recommendations and calls for action. This will likely influence the allocation of funds for the prevention, treatment, education and research in HF.     

腰丛联合坐骨神经阻滞在高龄患者髋关节置换中的应用

目的探讨腰丛联合坐骨神经阻滞对高龄髋关节置换术患者术后疼痛的缓解作用及对认知功能的保护机制。 方法选取2016年6月至2018年5月于海南省万宁市人民医院行单次全髋关节置换术的高龄患者120例,年龄80~100岁,纳入标准：年龄范围为80~100岁,美国麻醉医师协会(ASA)分级Ⅱ~Ⅲ级;符合全髋关节置换术相关手术指征;认知功能正常。排除标准：合并严重原发疾病者;合并精神病或神经系统疾病者;依从性较差者;对本研究麻醉方案过敏者。所有患者采用随机数字表法分为两组：全身麻醉组(GA组),腰丛-坐骨神经阻滞组(PCSNB组),每组各60例。比较两组术中情况(麻醉操作时间、手术时间、术中出血量、术中补液量),手术前后血清碱性成纤维细胞生长因子(bFGF)水平。采用视觉模拟量表(VAS)评估两组患者术后疼痛程度,采用简易精神状态量表(MMSE)及蒙特利尔认知评估量表(MoCA)评估两组患者认知功能。正态分布的计量资料采用t检验,同一指标在3个以上不同时间点上比较,采用重复测量方差分析。 结果PCSNB组麻醉操作时间显著高于GA组(t＝17.74,P<0.001),术中出血量及术中补液量均显著低于GA组(t＝7.56、14.59、7.60,均为P<0.001)。术后1 d两组血清bFGF水平均有所下降(t＝13.14、6.82,均为P<0.001),但PCSNB组血清bFGF水平显著高于GA组(t＝7.43,P <0.001)。PCSNB组术后2、12及24 h的VAS评分显著低于对照组(F＝8.03、6.56,均为P <0.001)。术后1 d,PCSNB组MMSE评分及MoCA评分均显著低于对照组(t＝3.89、4.58,均为P <0.001)。 结论腰丛联合坐骨神经阻滞可减轻高龄髋关节置换术患者术后疼痛,对患者认知功能具有保护作用,可能与bFGF水平有关。     

On-line computer estimation of carbon dioxide response curves

Anesthesiologists are concerned with the effect of various anesthetics on a patient's central nervous ventilatory control. The most widely accepted method of determining the effect of a drug is to compare carbon dioxide response curves ( e/PetCO₂, where e = minute ventilation [in L/min] andPetCO₂ = end-tidal carbon dioxide [in mm Hg]) measured before and after administration of the drug. Additional information concerning neuromechanical control can be obtained by also including a measure of the airway occlusion pressure (generally measured 100 ms after occlusion, i.e., P₁₀₀).To facilitate these measurements we have developed a portable, computer-controlled data acquisition system. It includes an Apple II+ computer and measures e,PetCO₂, and P₁₀₀. Each subject rebreathes exhaled carbon dioxide through a two-way breathing valve attached to a 9-liter reservoir, which is initially filled with 5% carbon dioxide and balance oxygen. Exhaled carbon dioxide concentrations are measured with an infrared medical gas analyzer on samples taken through a catheter connected at the mouthpiece. The exhaled flow is measured with a pneumotachograph in conjunction with a differential pressure transducer, and P₁₀₀ is determined with a Validyne MP45 pressure transducer.