Multiple regression analysis of twin data obtained from selected samples

The multiple regression analysis of twin data in which a cotwin's score is predicted from that of a proband (the member of a twin pair selected because of a deviant score) and the coefficient of relationship provides a powerful test of genetic etiology (DeFries and Fulker: Behav Genet 15:467-473, 1985). Moreover, when an augmented model containing an interaction term is fitted to the same data set, direct estimates of heritability (h2) and the proportion of variance owing to shared environmental influences (c2) are also obtained. In the present paper, the expected partial regression coefficients estimated from these models are derived, and the flexibility of the general approach is illustrated. An extended model is formulated for the analysis of data from combined samples of affected and control twin pairs that yields tests for differential h2 and c2 in the two groups as well as pooled estimates of these parameters. The application of these models is illustrated by an analysis of data from reading-disabled and control twin pairs. Because of the ease, flexibility, and utility of the multiple regression analysis of twin data, it is an appealing alternative to more traditional model-fitting approaches.     

Spontaneous regression of a temporal arachnoid cyst

Surgery is considered to be the standard therapy for arachnoid cysts (ACs). We report the case of a 13-year-old boy in whom a right temporal AC disappeared spontaneously over a period of 10 years. Bulging of the right temporal skull led to the detection of the cyst by computed tomography (CT) scan at the age of 3 years. There were no other clinical symptoms. Subsequent CT scans showed spontaneous regression of the cyst without surgical intervention. The question as to how ACs should be treated is discussed.     

安氏Ⅲ类错畸形病因的logistic分析

目的研究引起安氏Ⅲ类错牙合畸形的病因。方法对50例安氏Ⅲ类错牙合患者和50例正常牙合人作病因问卷调查,将结果用logistic法分析,提取有效病因。结果共有慢性扁桃体炎、遗传因素、咬上唇3项病因进入方程。结论按贡献大小,长期慢性扁桃体炎、经常咬上唇和遗传因素是导致安氏Ⅲ类错牙合畸形的危险因素。     

阿拉善黄鼠疫源地动物鼠疫预报的数学模型

根据我国阿拉善黄鼠鼠疫自然疫源地1981～1993年鼠疫监测资料，采用多元逐步曲线回归分析，建立了预报阿拉善黄鼠鼠疫流行的数学模型，其拟合率为100%，并得出影响鼠疫流行的主要因子为黄鼠密度和巢蚤指数。     

鼻咽癌病因学的病例—对照研究

本文以病例—对照的方法探讨了在黑龙江省与鼻咽癌发生有关的危险因素。调查鼻咽癌病例及对照共127对。在单因素与条件Logistic回归分析中均表明幼儿期食咸鱼(OR=5.5, χ²=4.92, P<0.05)及长期生活在烧煤的环境中(OR=1.894, χ²=4.655, P<0.05)可能与鼻咽癌的发生有关。此外,条件Logistic回归分析还发现,鼻窦炎病史也可能与鼻咽癌的发生有联系(B=1.385, exp(B)=3,995, P<0.1)。在对病例及对照的一级亲属患恶性肿瘤情况的调查中发现,鼻咽癌病例组有肿瘤家族史者多于对照组,其差异有统计学意义(χ²=10.32, P<0.01)。     

Evaluating risk factors associated with severe hypoglycaemia in epidemiology studies—what method should we use?

AIMS: To determine the most appropriate regression models to use when assessing risk factors for severe hypoglycaemia and to investigate the impact of model misspecification and its clinical implications. METHODS: A total of 1229 children with Type 1 diabetes (mean age 11.7 years sd 4.1), of which 605 (49.2%) were males, were studied. Prospective assessment of severe hypoglycaemia (an event leading to loss of consciousness or seizure) was made over the 9-year period, 1992-2001. Patients were seen every 3 months and episodes of hypoglycaemia along with clinical data were recorded. Over 70% of children never experienced a severe hypoglycaemic event. Data were analysed using the Poisson regression, negative binomial, zero-inflated Poisson (ZIP) and zero-inflated negative binomial (ZINB) models. The over-dispersion and likelihood ratio statistics were calculated and the analytical methods compared. RESULTS: The Poisson regression model did not fit the data well. The negative binomial and the zero inflated Poisson and negative binomial models fitted the data better than Poisson. CONCLUSIONS: The commonly used Poisson regression models to analyse hypoglycaemia epidemiology may lead to biased parameter estimates and incorrect determination of risk factors for hypoglycaemia. We recommend the use of the negative binomial or zero inflated models to examine any risk factors associated with severe hypoglycaemia. Careful consideration must be given to the interpretation of hypoglycaemia surveys and their analysis.     

增龄过程中心脏径限的变化及其影响因素

为探讨年龄增长及伴随的一些生理性变化对心脏径限的影响,对300余例20—81岁(平均46±16岁)的正常成人进行了超声心动图研究。多元逐步回归及协方差分析表明,左室壁厚度随年龄俱增,而左室舒张未期内径变化不大;室间隔/左室后壁厚度比值亦渐有增长,反映了室间隔的随龄增长稍快于左室后壁,故在增龄过程中,左室流出道稍有缩小;左房、主动脉根部和右室内径均有随年龄而增长的变化。二尖瓣舒张期 EF 斜率随年龄增长渐有下降,可能反映了左室顺应性的降低及二尖瓣弹性的减退。此外,一些心脏测值有性别差异,不少径限尚与体格大小或血压水平有相关关系。对于不同年龄组间心脏径限差异的原因,以及心脏径限彼此间的关系进行了分析和讨论,认为在临床上评价心脏径限正常与否和异常程度时,应考虑年龄、性别、体格大小、血压等因素的影响。     

多分类有序反应变量logistic回归应用条件的检验

目的 对多分类有序反应变量logistic回归的应用条件寻求科学合理的检验方法。方法 使用卡方分布的理论，SAS软件及抽样调查方法。结果 设计出多分类有序反应变量logistic回归应用条件的卡方检验方法，推导出反应变量取各水平的概率计算公式及卡方检验中理论值、自由度的计算公式，并在作者主持的国家医师资格临床实践技能考试研究中取得了成功效果。结论 多分类有序反应变量logistic回归得到完善和补充，具有较大的理论和实际意义。     

A simplified statistical method for local INR using linear regression

A simplified method of International Normalized Ratio (INR) derivation using linear regression of certified INR plotted against local prothrombin time (PT) results has been compared with INR from conventional orthogonal regression. Linear regression assumes error only with the local PT results whereas orthogonal regression assumes error with both reference and local results. The reliability of local INR derivation using lyophilized plasmas has been assessed in a collaborative study. INR from conventional fresh plasma International Sensitivity Index (ISI) calibrations have been compared with INR from calibrations with two types of lyophilized plasma, artificially depleted and coumarin.
Although calibration slopes differed with the two types of analysis and the different lyophilized plasmas, both gave reasonable approximations to fresh plasma ISI calibrations. With orthogonal regression the overall percentage INR deviation was 5.25% with the artificially depleted plasmas and 6.85% for the results with lyophilized coumarins. With the linear regression, deviation was 8.40% for the artificially depleted plasmas and 5.05% for coumarin-treated patients' lyophilized plasmas. The simpler regression method appears to be worthy of further study as the present report has demonstrated that if the calibrant plasmas are accurately certified with the thromboplastin International Reference Plasma (IRP) results approximate to the conventionally determined INR using the manual PT technique. Coagulometers require further assessment.     

农村地区高血压危险因素的病例对照研究

对四川省农村地区218例原发性高血压(其中包括109例临界高血压)进行配对(1:2)病例对照研究。资料分析采用了条件Logistic回归分析方法。研究结果提示心率、高血压家族史、环境噪声、体重指数(QI)等综合因素与临界高血压和确诊高血压均有显著的联系。心率、体重指数(QI)以及高血压家族史是原发性高血压较稳定的影响因素,心率可作为研究血压的必测指标。环境因素对原发性高血压的影响不可忽视。原发性高血压是遗传因素、环境因素等综合作用的结果。