Exploring interaction effects in small samples increases rates of false-positive and false-negative findings: results from a systematic review and simulation study

ObjectiveTo give a comprehensive comparison of the performance of commonly applied interaction tests.MethodsA literature review and simulation study was performed evaluating interaction tests on the odds ratio (OR) or the risk difference (RD) scales: Cochran Q (Q), Breslow–Day (BD), Tarone, unconditional score, likelihood ratio (LR), Wald, and relative excess risk due to interaction (RERI)-based tests.ResultsReview results agreed with results from our simulation study, which showed that on the OR scale, in small sample sizes (eg, number of subjects ≤ 250) the type 1 error rates of the LR test was 0.10; the BD and Tarone tests showed results around 0.05. On the RD scale, the LR and RERI tests had error rates around 0.05. On both scales, tests did not differ regarding power. When exposure prevented the outcome RERI-based tests were relatively underpowered (eg, N = 100; RERI power = 5% vs. Wald power = 18%). With increasing sample size, difference decreased.ConclusionIn small samples, interaction tests differed. On the OR scale, the Tarone and BD tests are recommended. On the RD scale, the LR and RERI-based tests performed best. However, RERI-based tests are underpowered compared with other tests, when exposure prevents the outcome, and sample size is limited.     

Cognitive and physical training for the elderly: Evaluating outcome efficacy by means of neurophysiological synchronization

Recent neuroscientific research has demonstrated that both healthy and pathological aging induces alterations in the co-operative capacity of neuronal populations in the brain. Both compensatory and neurodegenerative mechanisms contribute to neurophysiological synchronization patterns, which provide a valuable marker for age-related cognitive decline. In this study, we propose that neuroplasticity-based training may facilitate coherent interaction of distant brain regions and consequently enhance cognitive performance in elderly people. If this is true, this would make neurophysiological synchronization a valid outcome measure to assess the efficacy of non-pharmacological interventions to prevent or delay age-related cognitive decline. The present study aims at providing an objective, synchronization-based tool to assess cognitive and/or physical interventions, adopting the notion of Relative Wavelet Entropy. This mathematical model employs a robust and parameter-free synchronization metric. By using data mining techniques, a distance value was computed for all participants so as to quantify the proximity of their individual profile to the mean group synchronization increase. In support of our hypothesis, results showed a significant increase in synchronization, for four electrode pairs, in the intervention group as compared to the active control group. It is concluded that the novel introduction of neurophysiological synchronization features could be used as a valid and reliable outcome measure; while the distance-based analysis could provide a reliable means of evaluating individual benefits.     

磁共振弥散加权成像及表观弥散系数在儿童脑梗死中的诊断价值

目的探讨磁共振弥散加权成像（diffusionweightedmagneticresonanceimaging,DWI）及表观弥散系数（apparent diffusion coefficient,ADC）在脑梗死不同时期诊断及判断脑梗死转归中的价值。方法对26例患儿按发病就诊时间分为l期（0—72h）11例次,Ⅱ期（4-10d）12例次,Ⅲ期（10d以后）9例次,其中3例为复查,3例为复发脑梗死,共计29例次。对每例患儿进行MRI的T1加权像、配加权像、DWI序列扫描检查及ADC图像重建,于ADC图上取1个感兴趣区（regionsofinterest,ROI）,计算出ROI的平均ADC值,同样的方法计算出镜像健侧相对应区的平均ADC值,并计算平均相对ADC值。结果DWI图像改变I期全部病例均呈现高信号;Ⅱ期11例次呈现高信号,1例次为低信号;Ⅲ期1例次为正常信号,1例次为高信号,2例次为混杂信号,1例次较前减低,其余均为低信号。在I期患儿ROI平均ADC值较对侧相应区域平均ADC值均下降,随着时间的发展Ⅱ期、Ⅲ期平均ADC值逐渐升高,梗死灶I期、Ⅱ期、Ⅲ期平均ADC值分别为0．434×10^-3mm2／s、0．653×10^-3mm2／s、1．600×10^-3mm2／s,对侧相应区域平均ADC值分别为0．938×10^-3mm2／s、0．814×10^-3mm2／s、0．757×10^-3mm2／s;Ⅰ期、Ⅱ期、Ⅲ期相对ADC平均值随着时间发展逐渐升高,分别为（51．5±16．8）％、（79．2±30．0）％、（210．9±45．1）％,差异均有统计学意义（P均〈0．05）。结论弥散加权MRI及ADC平均值对脑梗死早期诊断具有重要价值;脑梗死病灶ADC值和相对ADC值在时间上的变化规律为准确地判断脑梗死时期提供客观依据;弥散加权MRI及ADC平均值能为临床治疗及判断预后提供有效手段。     

普拉提训练课程对大学女生身体素质提升的效果

目的研究普拉提核心力量训练对大学女生形态、心肺功能、平衡能力及灵活性指标的影响。方法40个大学女生按实验目的分为常规体育课程组(CK组)及普拉提训练课程组(PM组),PM组训练强度为每周2次时间为60~80 min的普拉提训练,训练持续16 w,训练前后测定形态、心肺功能、平衡能力及灵活性指标。结果协方差分析结果表明,普拉提训练课程能够显著影响大学女生心肺功能、灵活性及身体平衡能力。通过前后测试指标比较分析,PM组前测和后测数据有显著差异,其中大学女生体重显著下降1.09%(t=2.709;P=0.014),大腿围显著下降0.34%(t=2.554,P=0.019),腰围显著下降0.99%(t=4.223,P=0.000)、腰部皮褶厚度显著下降4.25%(t=4.908,P=0.000)、腹部皮褶显著下降1.54%(t=5.329,P=0.000)。PM组心肺功能呈现显著提升,其中肺活量显著增加27.05%(t=-26.544,P=0.000),最大吸氧量显著增加4.89%(t=-10.141,P=0.000),每搏输出量显著增加4.23%(t=-15.143,P=0.000),心率显著下降3.06%(t=4.886,P=0.000);PM组的柔韧性指标也呈现显著变化,坐位体前屈显著上升47.04%(t=-30.368,P=0.000),仰卧起坐次数显著增加45.70%(t=-17.512,P=0.000),Romberg显著提升达91.41%(t=-11.451,P=0.000),功能性伸展显著提升6.55%(t=-6.128,P=0.000)。结论普拉提运动能有效提升大学女生心肺功能、平衡能力及机体灵活性。     

川芎嗪联合小剂量阿斯匹林治疗脑梗塞216例疗效观察

目的 探讨盐酸川芎嗪联合小剂量阿斯匹林治疗脑梗塞方剂的治疗效果.方法 选取216例脑梗塞患者,观察治疗前后血液流变学指标变化.结果 盐酸川芎嗪合并小剂量阿斯匹林治疗能降低血液粘稠度,抑制血小板聚集,改善患者的预后.结论 盐酸川芎嗪联合小剂量阿斯匹林是安全有效,经济的治疗脑梗塞的治疗方剂值得推广应用.     

慢性肝炎肝硬化中医证型与血清肝纤维化指标关系的探讨

以放射免疫法测定152例慢性肝炎肝硬化患者的血清肝纤维化标志物透明质酸(HA)、Ⅲ型前胶原(hPCⅢ)和Ⅳ型胶原(Ⅳ-C)三项,旨在探讨中医证型与上述指标的关系。结果显示,各中医证型组的肝纤三项指标均为对照组升高,但改变有各自的特点,其中肝郁脾虚组的平均升高幅度最小,此为基础的两两比较发现,湿热中阻组肝纤三项均显著性升高;肝肾阴虚和瘀血阻络组以 HA、hPCⅢ升高为主。提示测定上述指标对慢性肝病患者的中医分型有一定指导意义,肝纤维化在肝郁脾虚阶段便已开始,湿热中阻是肝纤维化的活跃期,而血瘀则贯穿于肝纤维化的整个过程。     

新型农村合作医疗综合评价指标体系检验

目的评价所构建的“新型农村合作医疗综合评价指标体系”的科学性、合理性。方法采用信度、效度、区分度对综合评价指标体系进行评价。结果总体指标克朗巴赫α系数为0.8889;主成分分析表明指标体系具有较好的结构效度;聚类分析和方差分析表明有较好的区分能力。结论新型农村合作医疗综合评价指标体系具合理性、科学性、较好的信度、效度和区分度。     

头孢他美酯分散片在人体内的相对生物利用度及生物等效性

目的建立HPLC法测定人血浆中头孢他美的浓度,并研究头孢他美酯分散片在人体内的相对生物利用度及生物等效性。方法18名受试者随机均分成两组,先后单剂量po受试制剂或参比制剂后,采用HPLC法测定血药浓度,计算药动学参数并进行生物等效性判定。结果单次服用0.5 g受试制剂或参比制剂后的药动学参数AUC0→14、AUC0→∞、Tm ax、Cm ax、t1/2分别为22.07±3.98μg.h.m l-1和21.31±4.37μg.h.m l-1,22.62±4.06μg.h.m l-1和21.99±4.54μg.h.m l-1,2.42±0.55 h和2.61±0.50 h,4.16±0.74μg.m l-1和3.95±0.87μg.m l-1,2.24±0.26 h和2.48±0.33 h。实验制剂对参比制剂的相对生物利用度为105.0%±14.6%。两种制剂的药动学参数无明显差异。结论受试制剂与参比制剂具有生物等效性。     

浙江省文成县34所学校生活饮用水监测结果分析

目的调查台风暴雨之后,全县各学校的生活饮用水情况,防止传染病的发生,解决存在的问题。方法在全县范围内抽查34所学校的生活饮用水,其中20份自备水及23份自来水,按GB5750-85《生活饮用水标准检验法》及卫生部2001版《生活饮用水卫生规定》的方法进行检测。检验指标包括色度、浑浊度、pH值、总硬度、铁、锰、氨氮、亚硝酸氮、硝酸盐氮、硫酸盐、氟化物、细菌菌落总数、总大肠菌群和粪大肠菌群。结果20份自备水中合格率最低的是总大肠菌群和粪大肠菌群,合格率均为20%;23份自来水中合格率最低的是浑浊度,合格率为4.3%。结论文成县各学校的生活饮用水存在较大的卫生质量问题,不同来源的饮用水(自备水或自来水)基本上不合格。