The effect of omitted covariates on confidence interval and study power in binary outcome analysis: a simulation study

BACKGROUND/OBJECTIVES: The consequence of omitted but balanced covariates on odds ratio point estimation is well-known in the literature. When exposure or intervention has a non-null effect on disease outcome, omitted covariates lead to underestimation of the effect of exposure or intervention. However, the effect of omitted covariates on confidence interval and study power is unknown. STUDY DESIGN AND SETTING: A simulation study is carried out to assess the effect of omitted covariates on confidence interval and study power for a plausible range of scenarios. Coverage probability and study power are assessed systematically over a range of study size, type of omitted covariate and magnitude of effect. A real-life example using a randomised experiment on flies' sexuality is provided. RESULTS: When a balanced covariate is omitted, coverage probability was lowered by 2.9-80%. Likewise study power was reduced by as much as 58%. The impact becomes substantial when the covariate is continuous, has large variability and has a larger effect than the effect of exposure or intervention. The result from a real-life example concurs with the simulation finding. CONCLUSION: Omitting an important balanced covariate lowers both coverage probability and study power. This implies the need for thoughtful consideration of important covariates at the design as well as the analysis stages of a study.     

不同护生对临床教学评价分析

应届本科毕业护生与自考专升本护生虽然都可以获得本科文凭,但他们却有着完全不同的学习和生活经历,对临床实习的期望也不尽相同。然而,由于各种原因,在临床教学过程中,很多带教老师却对两种护生采取相同的带教方法。为了解两种护生对临床教学的评价,笔者对1年来在本院实习结束     

Effect of hyperlipidemia on endothelial VCAM-1 expression and the protective role of fenofibrate

The effect of hyperlipidemia and inflammation on endothelial functions was studied. The enrolled included control (basic chow), hyperlipidemia and fenofibrate-treated groups (high fat diet). The hyperlipidemia model was set up by four-week atherogenic diet, followed by a 16-week treatment in the fenofibrate-treated group (fenofibrate 40 mg/kg every day) and without treatment in the hyperlipidemia group, respectively. In the 20th week, serum lipid level and NO levels were measured, and the expression of vascular cell adhesion molecule-1 (VCAM-1) and cell adhesiveness in aortic endothelia observed by computer-aided system. Compared with the control group, hyperlipidemia rats showed lower levels of NO and ncreases in leukocyte accumulation on the endothelial surface, also stronger and more extensive endothelial expression of VCAM-1. In fenofibrate-treated group, the expression of VCAM-1 and leukocyte accumulation on the endothelial surface was decreased, while serum levels of NO were increased as compared with hyperli pidemia group. Hyperlipidemia can inhibit the NO activity and promote the damage of VACA-1 to aortic endothelia. Fenofibrate can effectively prevent the pathogenesis of atherosclerosis by restoring NO levels and down-regulating the VCAM-1 expression.     

A randomized controlled trial of calcium plus vitamin D supplementation and risk of benign proliferative breast disease

Experimental evidence provides strong support for anti-carcinogenic effects of calcium and vitamin D with respect to breast cancer. Observational epidemiologic data also provide some support for inverse associations with risk. We tested the effect of calcium plus vitamin D supplementation on risk of benign proliferative breast disease, a condition which is associated with increased risk of breast cancer. We used the Women’s Health Initiative randomized controlled trial. The 36,282 participants were randomized either to 500 mg of elemental calcium as calcium carbonate plus 200 IU of vitamin D₃ (GlaxoSmithKline) twice daily (n = 18,176) or to placebo (n = 18,106). Regular mammograms and clinical breast exams were performed. We identified women who had had a biopsy for benign breast disease and subjected histologic sections from the biopsies to standardized review. After an average follow-up period of 6.8 years, 915 incident cases of benign proliferative breast disease had been ascertained, with 450 in the intervention group and 465 in the placebo group. Calcium plus vitamin D supplementation was not associated with altered risk of benign proliferative breast disease overall (hazard ratio = 0.99, 95% confidence interval = 0.86–1.13), or by histologic subtype. Risk varied significantly by levels of age at baseline, but not by levels of other variables. Daily use of 1,000 mg of elemental calcium as calcium carbonate plus 400 IU of vitamin D₃ for almost 7 years by postmenopausal women did not alter the overall risk of benign proliferative breast disease.     

高三酰甘油血症血流变化特点与一氧化氮活性及血管扩张效应改变的相关研究

目的 :探讨高三酰甘油 (TG)血症时血流动力学变化特点及其对血管内皮功能的影响机制。方法 :以 2 0例正常人、6 0例高TG血症患者 (其中 30例予以饮食治疗、30例予吉非罗齐治疗 )为观察对象 ,以肱动脉B超测量血管结构、血流和内皮依赖的舒张功能改变 ,并检测血浆一氧化氮 (NO)、氧化型低密度脂蛋白 (oxLDL)、血脂、血糖的变化。结果 :与正常对照组比较 ,除了常规血脂生化指标异常升高外 ,TG血症患者还有血oxLDL浓度升高、NO活性下降 ,且NO水平与TG、总胆固醇 (TC)、低密度脂蛋白胆固醇 (LDL C)和oxLDL浓度呈负相关。血管超声中心肌内温度、收缩期内径和舒张期内径差异无统计学意义 ,而平均血流速度 (Vm)、平均剪切率 (MSR)以及血流介导的扩张效应 (FMD)均显著减小 ,与NO水平呈正相关。 8周的低脂饮食治疗可使总胆固醇TC、TG水平下降 ,但NO、oxLDL和血管超声差异无统计学意义 ;吉非罗齐治疗组血TG、TC、LDL C和oxLDL浓度下降、NO浓度增高 ,血管超声FMD、Vm、MSR显著升高 ,而结构尚未见明显改变。结论 :高TG血症时TC、TG、LDL C水平和oxLDL共同参与了内皮的损伤机制 ,血流减缓、血流剪切率下降与NO活性的下降密切相关 ,临床表现为血管舒张功能的下降 ,调脂治疗有利于内皮舒张功能的改善。     

儿童重症监护病房镇痛镇静治疗撤药模式对戒断综合征的影响

目的调查儿童重症监护病房(PICU)机械通气患儿镇痛镇静治疗情况,探讨不同撤药模式对戒断综合征的影响。方法单中心前瞻性队列研究。以2016年4月1日至2017年4月30日入住上海儿童医学中心PICU需机械通气并连续使用苯二氮类药物和(或)阿片类药物≥5 d的112例患儿为研究对象,根据患儿撤药开始后每日镇痛镇静药物剂量是否较前1日增加≥50%,分为不稳定撤药模式20例(17.9%)、稳定撤药模式92例(82.1%)。收集患儿人口统计学特征、临床特征、镇痛镇静药物暴露等指标,以Mann-Whitney U检验等方法比较不同撤药模式组患儿临床特征及发生与未发生戒断综合征患儿的临床特征,并通过Logistic回归探索戒断综合征发生的危险因素。结果纳入112例患儿,戒断综合征发生率41.1%(46/112)。不稳定撤药组患儿的第3代小儿死亡危险评分(PRISM-Ⅲ)[10.0(3.5,12.0)比6.0(2.0,10.0),U=654.50,P=0.043]、撤机后再插管比例[35.0%(7/20)比7.6%(7/92),P=0.003]均明显高于稳定撤药模式组。发生戒断综合征患儿总镇痛镇静时间更长[19.5(16.8,24.3)比10.0(7.0,17.3)d,U=743.50,P<0.01]、不稳定撤药发生率更高[32.6%(15/46)比7.6%(5/66),χ^2=11.58,P=0.001]、PICU住院时间更长[19.0(15.8,25.3)比12.0(8.8,17.0)d,U=755.00,P<0.01]、住院总费用更高[8.9(5.7,10.9)比5.3(3.2,7.9)万元,U=804.00,P<0.01]。多因素Logistic回归分析发现不稳定撤药[比值比(OR)=4.85,95%可信区间(CI)1.39~16.91,P=0.013]、肝移植围手术期(OR=6.97,95%CI 1.25~39.04,P=0.027)和总咪达唑仑剂量≥34.7mg/kg(OR=8.12,95%CI 3.09~21.37,P<0.01)是发生戒断综合征的危险因素。结论不稳定撤药患儿更容易发生戒断综合征,避免不稳定撤药可能使镇痛镇静治疗患儿获益。     

浅论后疫情时代混合式教学背景下的新型师生关系 ——基于某医学院公共英语教学的案例研究

本文采用叙事研究法记录分析了某医学院3位外语教师及其学生的互动过程,探讨了后疫情时代混合式教学背景下医学院校英语教学中师生关系的特点和发展路径.结果表明新形势下原有的师生关系受到了解构和冲击,师生关系从传统对立逐渐走向了平等、宽容和建设性;疫情特殊的时空条件增强了师生之间的凝聚力,对立的师生关系趋向融合,疏离的师生关系...     

中国助产士人力资源现状调查研究

目的通过调查了解全国的助产士人力资源现状。方法 2017年12月—2018年11月,通过判断抽样和便利抽样法选取中国妇幼保健协会成员机构中的三级和二级医院作为调查对象,使用自行编制的中国助产士人力资源现状调查表进行数据收集,调查单位覆盖国内22个省、自治区、直辖市。结果共发放问卷1 254份,共回收有效问卷1 213份,问卷的有效率为97.4%;国内产科平均床位使用率为90%;平均每所医院拥有助产士12名,以25～34岁、工作年限<10年、初级职称的助产士为主;助产士的平均外出培训率为12%;不同等级和类型医院的年分娩量、产科床位使用率、助产士人数和构成比较,差异有统计学意义(P<0.05)。结论国内助产士的人员紧缺状况有所缓解但人力仍不足,助产士的学历提升,但助产人员内部构成仍不合理,且不同等级和类型助产医疗机构的资源利用率不同,需进一步开展助产专科教育和培训,优化助产士人力资源配置,实现合理利用助产资源。     

强化质量监督和确保医疗安全的探讨

文章介绍了在医疗质量管理中,启用质量监督机制,使行政管理与监督分立,改变了传统的由主管部门进行质量控制、评价、处理的管理模式,形成执行和监督并重的管理体制,增强了行政和制度的执行力,从而达到提高医疗质量、保证医疗安全的目的.     

High prevalence of high grade anal intraepithelial neoplasia in HIV-infected women screened for anal cancer

There is no consensus on optimal screening for anal cancer (AC) in HIV+ women. Seven hundred fifteen unique asymptomatic women in a high-prevalence HIV+ community were screened for AC with anal cytology and triage to high-resolution anoscopy after routine screening was implemented in a large urban hospital system. Of these, 75 (10.5%) had an abnormal anal cytology and 29 (38.7%) of those with an abnormality had high-grade anal intraepithelial neoplasia (AIN). Women with poorly controlled HIV were significantly more likely to have high-grade AIN (P = 0.03). Given the high rate of AIN in screened HIV-infected women, routine AC screening in all HIV-infected women should be strongly considered.