Methods for Constructing and Assessing Propensity Scores

Objectives

To model the steps involved in preparing for and carrying out propensity score analyses by providing step-by-step guidance and Stata code applied to an empirical dataset.

Study Design

Guidance, Stata code, and empirical examples are given to illustrate (1) the process of choosing variables to include in the propensity score; (2) balance of propensity score across treatment and comparison groups; (3) balance of covariates across treatment and comparison groups within blocks of the propensity score; (4) choice of matching and weighting strategies; (5) balance of covariates after matching or weighting the sample; and (6) interpretation of treatment effect estimates.

Empirical Application

We use data from the Palliative Care for Cancer Patients (PC4C) study, a multisite observational study of the effect of inpatient palliative care on patient health outcomes and health services use, to illustrate the development and use of a propensity score.

Conclusions

Propensity scores are one useful tool for accounting for observed differences between treated and comparison groups. Careful testing of propensity scores is required before using them to estimate treatment effects.     

生物样品中铯-137活度浓度的两种分析方法比较

目的探讨生物样品中铯-137活度浓度的γ能谱法与放射化学法分析结果的一致性。方法对多种生物样品分别用这两种方法进行比对测量,并对结果进行统计检验和线性拟合。结果两种方法的实验结果没有显著性差别,并且线性相关。结论两种方法可视工作需要相互替代。     

二氧化氯消毒剂有效成分区分测定方法的比较

目的为了科学地评价二氧化氯产品的质量和性能,引导二氧化氯产品的正确使用,有必要筛选出一套能准确区分测定活化后二氧化氯消毒液中ClO2、Cl2、ClO2^-、ClO3^-浓度的方法。方法采用碘量法、丙二酸碘量法、改进丙二酸碘量法、五步碘量法对稳定性二氧化氯产品中的ClO2、Cl2、ClO2^-和ClO3^-的含量进行区分测定,评价比较了各种测定方法的优缺点和适用性。结果经碘量法测定,经盐酸活化的液体稳定性二氧化氯产品中ClO2含量为20．23mg／ml,与产品的标示值基本一致;而经丙二酸碘量法进一步测得该液体稳定性二氧化氯产品中ClO2含量为19．99mg／ml,Cl2含量为0．35mg／ml;而采用改进丙二酸碘量法和五步碘量法测得该液体稳定性二氧化氯产品中二氧化氯的活化率分别为88．0％,75．6％;可有效区分出二氧化氯消毒剂中的二氧化氯与亚氯酸根离子。结论采用改进丙二酸碘量法和五步碘量法可以区分测定出活化后的稳定性二氧化氯产品中的活性二氧化氯与残留的亚氯酸根含量,而碘量法和丙二酸碘量法则无法区分测定二氧化氟和亚氯酸根离子。     

Beneficial Effects of Plant Extracts and Bioactive Food Components in Childhood Supplementation

The pivotal role of childhood nutrition has always roused a growing interest from the scientific community. Plant extracts and bioactive dietary components play a significant role in the maintenance of human health and wellness, with the potential to modulate risk factors and manage symptoms for a large number of common childhood disorders such as memory impairment, respiratory illnesses, gastrointestinal disorders, metabolic derangements, and pathologies related to the oral cavity. This review is designed to highlight the health benefits of botanical extracts and bioactive dietary components in children as evidenced by clinical trials, considering their safety with regards to childhood sensibilities. The supplementation of children with the herbal extracts or bioactive components mentioned in this review leads to the conclusion that they are useful for treating various ailments, with no serious adverse events being reported. However, for the limited number of investigations specifically focused on the safety of such products in children, time is needed to expand the literature data covering the safety of childhood supplementation with botanical extract and bioactive food components.     

生物材料中克伦特罗的提取方法

目的 探讨生物材料中克伦特罗的提取方法。方法 用5种方法分别提取血液中的克伦特罗,用气相色谱-质谱提取离子方式测定其含量,比较提取效果。结果 盐酸克伦特罗的标准曲线在0．01～10mg／L有良好的线性关系,r=0．9999,检出限为0．005mg／L。血液中添加lμg／ml盐酸克伦特罗时,用0．01 mol／L盐酸和无水乙醇浸提,在pH=11条件下用氯仿萃取,该方法的平均回收率和RSD分别为96．5％和5．21％(n=6)。结论 该方法操作简便,结果可靠,且无需衍生化,适用于生物材料中克伦特罗的快速测定。     

二恶英类化学物质生物检测方法研究进展

应用生物检测手段(如生物法、免疫测定及体外受体结合实验等)检测环境污染物是环境检测领域一个研究热点,特别在二恶英类化合物的痕量分析中的作用令人瞩目。本文综述了用于二恶英类化合物筛选的几类生物检测方法的原理和优缺点,对各种方法进行了比较,指出建立二恶英两级检测的体系的合理性以及发展方向。     

大鼠肝细胞简易培养方法及某些生物学特性的研究

本文介绍一种改良的方法培养大鼠肝细胞,简便易行,可在一般条件的实验室开展,细胞活力良好,形态和超微结构正常,正常二倍体核型,可在体外存活达3个月,并对肝细胞生长过程中某些酶、蛋白质、激素、甘胆酸等作了生化、组化、放射免疫测定及6种微量元素的检测,同时进行了 HBV 感染体外培养肝细胞的试验。     

Plant Proteins: Assessing Their Nutritional Quality and Effects on Health and Physical Function

Consumer demand for plant protein-based products is high and expected to grow considerably in the next decade. Factors contributing to the rise in popularity of plant proteins include: (1) potential health benefits associated with increased intake of plant-based diets; (2) consumer concerns regarding adverse health effects of consuming diets high in animal protein (e.g., increased saturated fat); (3) increased consumer recognition of the need to improve the environmental sustainability of food production; (4) ethical issues regarding the treatment of animals; and (5) general consumer view of protein as a “positive” nutrient (more is better). While there are health and physical function benefits of diets higher in plant-based protein, the nutritional quality of plant proteins may be inferior in some respects relative to animal proteins. This review highlights the nutritional quality of plant proteins and strategies for wisely using them to meet amino acid requirements. In addition, a summary of studies evaluating the potential benefits of plant proteins for both health and physical function is provided. Finally, potential safety issues associated with increased intake of plant proteins are addressed.     

Meeting Preferences for Specific Contraceptive Methods: An Overdue Indicator

Fertility surveys have rarely asked people who are using contraception about the contraceptive method they would like to be using, implicitly assuming that those who are contracepting are using the method they want. In this commentary, we review evidence from a small but growing body of work that oftentimes indicates this assumption is untrue. Discordant contraceptive preferences and use are relatively common, and unsatisfied preferences are associated with higher rates of method discontinuation and subsequent pregnancy. We argue that there is opportunity to center autonomy and illuminate the need for and quality of services by building on this research and investing in the development of survey items that assess which method people would like to use, as well as their reasons for nonpreferred use. The widespread adoption of questions regarding method preferences could bring indicators of reproductive health services into closer alignment with the needs of the people they serve.     

原发性肝癌的特异性生物学标志物的分析

目的探讨肝癌特异性甲胎蛋白（HS-AFP）、甲胎蛋白（AFP）和γ-谷氨酰转肽酶同工酶Ⅱ（GGT-Ⅱ）对肝硬化患者肝癌发生风险的预警价值。方法对452例肝硬化患者进行跟踪随访15个月,了解肝癌发生情况,分析比较HS-AFP、GGT-Ⅱ和AFP预测肝硬化患者发生肝癌风险的价值。结果 HS-AFP、GGT-Ⅱ阳性组癌变率高于AFP阳性组,但前两者差异不明显;HS-AFP与GGT-Ⅱ及AFP之间存在互补性,其中HS-AFP和GGT-Ⅱ联合检测预测肝硬化癌变的敏感性、特异性和准确度分别达73.2%、93.1%、92.3%。结论 HS-AFP、GGT-Ⅱ和AFP对肝硬化癌变均有预测价值;HS-AFP和GGT-Ⅱ预测肝癌的特异性、准确度优于AFP;HS-AFP与GGT-Ⅱ预测肝癌的特异性、准确度相似;多项指标联合检测可提高预测肝硬化癌变的敏感性、特异性和准确度。     

Cost-Savings from the Provision of Specific Contraceptive Methods in 2009

BackgroundPrevious studies have shown that contraceptive provision generates significant public sector cost-savings by preventing health care and social service expenditures on unintended pregnancies. Over the past decade, women's contraceptive options have expanded considerably, calling for the need to better understand the relative cost-benefit of new contraceptive methods.MethodsWe estimated the number of pregnancies averted by each specific contraceptive method by subtracting the total number of pregnancies expected under Family PACT from the total number of pregnancies that would be expected if the program were not available. The cost of providing each method was compared with the savings in reduced public expenditures from averted pregnancies. A resultant cost–benefit ratio was calculated for 11 specific contraceptive methods provided to women under Family PACT.ResultsEvery contraceptive method studied saved more in public expenditures for unintended pregnancy than it costs to provide. Over half (51%) of the pregnancies averted in 2009 were attributable to the most commonly used method, oral contraceptives. Injectable methods accounted for 13% of averted pregnancies, followed by intrauterine contraceptives (12%), and barrier methods (9%). Intrauterine contraception and contraceptive implants had the highest cost-savings with approximately $5.00 of savings for every dollar spent for users of these methods.ConclusionsBecause no single method is recommended clinically for every woman, it is medically and fiscally advisable to offer women all contraceptive methods to enable them to choose methods that best meet their needs, increasing the likelihood of compliance with the method chosen and prevention of unintended pregnancies.     

大鼠特异性体液免疫毒性两种评价方法的可行性

目的建立大鼠28天染毒的特异性体液免疫毒性模型,说明溶血空斑试验和血清溶血素试验用于评价大鼠特异性体液免疫毒性的可行性。方法雄性Wistar大鼠40只,体重180~200 g,随机分为对照组和5,10,20 mg/kg环磷酰胺(已知的免疫抑制剂)染毒组,每组10只大鼠,各剂量组每日灌胃染毒1次,连续28 d,对照组给予生理盐水;染毒第24天,大鼠腹腔注射1 ml 10%绵羊红细胞进行免疫;染毒结束后24 h,断头处死大鼠,取脾脏,制备脾细胞悬液,进行溶血空斑测定;收集血液,制备血清,进行血清溶血素试验。结果5,10和20 mg/kg环磷酰胺染毒组大鼠的溶血空斑数(分别为159.6±91.8,93.6±14.8,39.8±11.0)及血清溶血素水平(分别为125.6±38.5,36.4±5.9,1.5±0.3)低于对照组(溶血空斑数为355.0±96.3,血清溶血素水平为283.1±96.3),差异有显著性(P<0.05)。结论溶血空斑试验和血清溶血素试验两种方法用于评价大鼠特异性体液免疫功能具有可行性,可为我国化学品免疫毒性评价方法的建立提供参考。     

Construction of River Model Biofilm for Assessing Pesticide Effects

Due to the high importance of biofilms on river ecosystems, assessment of pesticides’ adverse effects is necessary but is impaired by high variability and poor reproducibility of both natural biofilms and those developed in the laboratory. We constructed a model biofilm to evaluate the effects of pesticides, consisting in cultured microbial strains, Pedobacter sp. 7-11, Aquaspirillum sp. T-5, Stenotrophomonas sp. 3-7, Achnanthes minutissima N71, Nitzschia palea N489, and/or Cyclotella meneghiniana N803. Microbial cell numbers, esterase activity, chlorophyll-a content, and the community structure of the model biofilm were examined and found to be useful as biological factors for evaluating the pesticide effects. The model biofilm was formed through the cooperative interaction of bacteria and diatoms, and a preliminary experiment using the herbicide atrazine, which inhibits diatom growth, indicated that the adverse effect on diatoms inhibited indirectly the bacterial growth and activity and, thus, the formation of the model biofilm. Toxicological tests using model biofilms could be useful for evaluating the pesticide effects and complementary to studies on actual river biofilms.     

Methods of Assessing Serial Films of the Pneumoconioses: a Review

This is a review of all known studies of methods of readingserial postero-anterior chest X-rays to obtain measures of changefrom one film to the next. Only those trials reported since1965 are relevant: in 7 of them (involving some 17 readers anda total of nearly 4000 films) reading side-by-side in knownchronological sequence was compared with independent randomizedreading. In side-by-side reading, disguise of temporal orderhas been attempted, and various methods of assessing changehave been tried. Other relevant information is discussed. Onthe evidence from British and Canadian sources, side-by-sidereading is the method of choice, although how to record changewill depend on the objective. The American evidence indicateslittle difference between methods, but side-by-side readingis still preferred if only because of its relative simplicity. Professor F. D. K. Liddell, Department of Epidemiology and Health, McGill University, 3775 University Street, Montreal, Quebec, Canada H3A 2B4.