Constrained empirical-likelihood confidence regions in nonignorable covariate-missing data problems

Missing covariates in regression analysis are a pervasive problem in medical, social, and economic researches. We study empirical-likelihood confidence regions for unconstrained and constrained regression parameters in a nonignorable covariate-missing data problem. For an assumed conditional mean regression model, we assume that some covariates are fully observed but other covariates are missing for some subjects. By exploitation of a probability model of missingness and a working conditional score model from a semiparametric perspective, we build a system of unbiased estimating equations, where the number of equations exceeds the number of unknown parameters. Based on the proposed estimating equations, we introduce unconstrained and constrained empirical-likelihood ratio statistics to construct empirical-likelihood confidence regions for the underlying regression parameters without and with constraints. We establish the asymptotic distributions of the proposed empirical-likelihood ratio statistics. Simulation results show that the proposed empirical-likelihood methods have a better finite-sample performance than other competitors in terms of coverage probability and interval length. Finally, we apply the proposed empirical-likelihood methods to the analysis of a data set from the US National Health and Nutrition Examination Survey.     

Inter-ictal assay of peripheral circulating inflammatory mediators in migraine patients under adjunctive cervical non-invasive vagus nerve stimulation (nVNS): A proof-of-concept study

Objective

To assay peripheral inter-ictal cytokine serum levels and possible relations with non-invasive vagus nerve stimulation (nVNS) responsiveness in migraineurs.

Envarsus,una novedad para los nefrólogos del trasplante: estudio observacional retrospectivo

The aim of this study was to evaluate the trough concentrations (Cp_trough) and the tacrolimus dosage regimen after the conversion of Prograf or Advagraf to Envarsus (new pharmaceutical form with MeltDose technology that improves the absorption of fat-soluble drugs) in patients with stable renal transplantation, and their renal function.We selected stable renal transplant patients who were converted to Envarsus. Two periods were defined: Baseline and Conversion (Envarsus) and they were stratified according to the pharmaceutical form used in the Baseline period. Sixty-one patients were included (24 with Advagraf and 37 with Prograf), with an average age of 52 years. The mean post-transplant time at the time of conversion to Envarsus was 76.3 months and the mean follow-up in the Baseline and Conversion period was 10.1 months and 11.6 months, respectively.In the Prograf and Envarsus group, the Cp_trough medians were 6.6 vs 6.4 ng/mL (P = .636), with a mean daily dose that decreased significantly from 3 mg to 2 mg (P < .001), respectively, maintaining the filtration rate.The median Cp_trough values in the Advagraf and Envarsus groups were 5.7 ng/mL and 6.3 ng/mL (P = .07), with a median daily dose of 7 mg and 4 mg (P < .001), respectively, and the same renal function.In stable renal transplant patients, the conversion from Advagraf to Envarsus has allowed the dose of tacrolimus to be reduced by 42.9% and, in the case of Prograf, by 33.3%, maintaining similar Cp_trough values, without renal function being altered.     

Impacto del primer año de tratamiento sustitutivo renal en la hospitalización de una comunidad autónoma

Introduction and objectivesChronic kidney disease has a high prevalence and economic impact, and an increased risk of hospitalization. Although there are public regional and country registries, we have not found references to estimate the impact of renal replacement therapy (RRT) on hospital admissions.MethodsWe obtained authorization from the ethics committee and health authorities to integrate the REMER [Madrid Kidney Disease Registry] (2013-2014) and Minimum Basic Data Set (2013-2015) databases and to analyze the admissions during the first year of RRT.Results767 patients started RRT in all the hospitals of our region across all RRT modalities. More than a third of the patients start dialysis during a hospital admission. This unplanned start, more common in HD than PD, shows relevant differences in patient profile or admission characteristics.Without considering this initial episode, almost 60% of patients were admitted during their first year. The hospitalization rate was 1.2 admissions/patient, higher in HD than in TX or PD; the mean length of stay was 8.6 days.The estimated cost of admissions during the first year is €12,006/patient. Our analysis ensures the exhaustive inclusion of all episodes and accurate estimation based on the discharge form.ConclusionThe impact of RRT on hospitals has been underestimated and is very relevant when calculating the total cost of RRT. Results from other countries cannot be extrapolated due to differences in the health system and patient profile. The integration of clinical databases could open up an opportunity that needs only institutional support for its development.     

Echocardiographic assessment at rest and during stress in patients with intermittent claudication

Objective. Skeletal muscle perfusion during walking relies on complex interactions between cardiac activity and vascular control mechanisms, why cardiac dysfunction may contribute to intermittent claudication (IC) symptoms. The study aims were to describe cardiac function at rest and during stress in consecutive IC patients, to explore the relations between cardiac function parameters and treadmill performance, and to test the hypothesis that clinically silent myocardial ischemia during stress may contribute to IC limb symptomatology. Design. Patients with mild to severe IC (n?=?111, mean age 67 y, 52% females, mean treadmill distance 195 m) underwent standard echocardiography, dobutamine stress echocardiography (SE) and treadmill testing. The patient cohort was separated in two groups based on treadmill performance (HIGH and LOW performance). Results. Ten patients (9%) had regional wall motion abnormalities of which three had left ventricular ejection fraction <50% at standard echocardiography. A majority had lower than expected systolic- and diastolic ventricular volumes. LOW performers had smaller diastolic left ventricular volumes and lower global peak systolic velocity during dobutamine stress. No patient demonstrated significant cardiac dysfunction during dobutamine provocation that was not also evident at standard echocardiography. Conclusions. Most IC patients were without signs of ischemic heart disease or cardiac failure. The majority had small left ventricular volumes. The hypothesis that clinically silent myocardial ischemia impairing left ventricular function during stress may contribute to IC limb symptomatology was not supported.

Trial registration: ClinicalTrials.gov identifier: NCT01219842.     

甲状腺功能减退与子宫内膜癌的相关性分析

 目的 探讨甲状腺功能减退与子宫内膜癌（EC）的关系及EC患者癌组织分化程度和雌激素受体（ER）、孕激素受体（PR）的表达与甲状腺功能之间的关系。方法 选取2015年1月—2018年7月我院收治的EC患者113例，同时随机选取年龄与EC组相匹配的此段时间内我院健康体检的妇女156例作为对照组，检测血清促甲状腺激素（TSH）、甲状腺激素（FT4）。比较两组间甲状腺功能减退的患病率，并利用免疫组织化学法测定EC患者手术切除标本的癌组织中ER、PR的表达，分析EC患者癌组织分化程度及癌组织中ER、PR的表达与甲状腺功能之间的相关性。结果 EC组甲状腺功能减退的患病率较对照组高（P<0.000）。低分化EC患者的TSH高于中分化EC患者（P=0.025）。EC手术切除标本的癌组织中ER、PR阳性与阴性患者的TSH、FT4差异无统计学意义（P>0.05）。结论 甲状腺功能减退与EC具有相关性。     

Liguzinediol对阿霉素诱导的慢性心衰大鼠心功能的影响

目的 通过阿霉素（Dox）复制大鼠慢性心力衰竭（CHF）模型，观察Liguzinediol对CHF大鼠心功能的影响。方法 通过血流动力学观察Liguzinediol对Dox（腹腔注射，2 mg/kg）诱导的CHF大鼠左心室内压最大上升/下降速率(±dp/dt_max)、左心室内压(LVSP)、动脉收缩压(ASP)、动脉舒张压(ADP)和心率(HR)的变化；观察Liguzinediol对血清一氧化氮（NO）、一氧化氮合成酶（NOS）、超氧化物歧化酶（SOD）、肿瘤坏死因子-α（TNF-α）和白细胞介素-6（IL-6）以及血浆中丙二醛（MDA）的影响。结果 Liguzinediol能增加LVSP、+dp/dt_max、ASP、ADP、AP、HR，降低-dp/dt_max(P<0.05~0.01)；降低NO、iNOS以及MDA的浓度，同时增强了SOD的活性(P<0.05~0.01)；抑制IL-6和TNF-α的生成(P<0.05~0.01)。结论 Liguzinediol可明显改善Dox诱导的CHF大鼠血流动力学指标，减少模型大鼠炎症因子的释放以及抑制氧自由基的生成。