Statistical studies of infectious disease incidence

Methods for the analysis of data on the incidence of an infectious disease are reviewed, with an emphasis on important objectives that such analyses should address and identifying areas where further work is required. Recent statistical work has adapted methods for constructing estimating functions from martingale theory, methods of data augmentation and methods developed for studying the human immunodeficiency virus–acquired immune deficiency syndrome epidemic. Infectious disease data seem particularly suited to analysis by Markov chain Monte Carlo methods. Epidemic modellers have recently made substantial progress in allowing for community structure and heterogeneity among individuals when studying the requirements for preventing major epidemics. This has stimulated interest in making statistical inferences about crucial parameters from infectious disease data for such community settings.     

A statistical algorithm for detecting cognitive plateaus in Alzheimer’s disease

Repeated neuropsychological measurements, such as mini-mental state examination (MMSE) scores, are frequently used in Alzheimer’s disease (AD) research to study change in cognitive function of AD patients. A question of interest among dementia researchers is whether some AD patients exhibit transient “plateaus” of cognitive function in the course of the disease. We consider a statistical approach to this question, based on irregularly spaced repeated MMSE scores. We propose an algorithm that formalizes the measurement of an apparent cognitive plateau, and a procedure to evaluate the evidence of plateaus in AD using this algorithm based on applying the algorithm to the observed data and to data sets simulated from a linear mixed model. We apply these methods to repeated MMSE data from the Michigan Alzheimer’s Disease Research Center, finding a high rate of apparent plateaus and also a high rate of false discovery. Simulation studies are also conducted to assess the performance of the algorithm. In general, the false discovery rate of the algorithm is high unless the rate of decline is high compared with the measurement error of the cognitive test. It is argued that the results are not a problem of the specific algorithm chosen, but reflect a lack of information concerning the presence of plateaus in the data.     

The Self-Forgiveness Process of Caregivers After the Death of Care-Receivers Diagnosed With Alzheimer's Disease

ABSTRACT

This study explores the relationship of self-forgiveness and adaptive coping, religious/spiritual practices, social support, decreased grief, and mental well-being. 133 caregivers were surveyed. Bivariate analysis and stepwise regression models revealed that decreased grief, adaptive coping, and social support were significant in explaining the variation in self-forgiveness. This is one of the first studies to address self-forgiveness as part of the grieving process of Alzheimer's caregivers. Future directions are explored supporting inclusion of self-forgiveness as an aspect of grief and adaptive coping; which is further enhanced by the level of social support experienced by the caregiver.     

Premature Deaths,Statistical Lives,and Years of Life Lost: Identification,Quantification, and Valuation of Mortality Risks

Mortality effects of exposure to air pollution and other environmental hazards are often described by the estimated number of “premature” or “attributable” deaths and the economic value of a reduction in exposure as the product of an estimate of “statistical lives saved” and a “value per statistical life.” These terms can be misleading because the number of deaths advanced by exposure cannot be determined from mortality data alone, whether from epidemiology or randomized trials (it is not statistically identified). The fraction of deaths “attributed” to exposure is conventionally derived as the hazard fraction (R – 1)/R, where R is the relative risk of mortality between high and low exposure levels. The fraction of deaths advanced by exposure (the “etiologic” fraction) can be substantially larger or smaller: it can be as large as one and as small as 1/e (≈0.37) times the hazard fraction (if the association is causal and zero otherwise). Recent literature reveals misunderstanding about these concepts. Total life years lost in a population due to exposure can be estimated but cannot be disaggregated by age or cause of death. Economic valuation of a change in exposure-related mortality risk to a population is not affected by inability to know the fraction of deaths that are etiologic. When individuals facing larger or smaller changes in mortality risk cannot be identified, the mean change in population hazard is sufficient for valuation; otherwise, the economic value can depend on the distribution of risk reductions.     

Air Nicotine and Saliva Cotinine as Indicators of Workplace Passive Smoking Exposure and Risk1

We model nicotine from environmental tobacco smoke (ETS) in office air and salivary cotinine in nonsmoking U.S. workers. We estimate that: an average salivary cotinine level of 0.4 ng/ml corresponds to an increased lifetime mortality risk of 1/1000 for lung cancer, and 1/100 for heart disease; >95% of ETS-exposed office workers exceed OSHA's significant risk level for heart disease mortality, and 60% exceed significant risk for lung cancer mortality; 4000 heart disease deaths and 400 lung cancer deaths occur annually among office workers from passive smoking in the workplace, at the current 28% prevalence of unrestricted smoking in the office workplace.     

Exploration of associations between governance and economics and country level foot-and-mouth disease status by using Bayesian model averaging

Summary.  Using Bayesian model averaging, we quantify associations of governance and economic health with country level presence of foot-and-mouth disease (FMD) and estimate the probability of the presence of FMD in each country from 1997 to 2005. The Bayesian model averaging accounted for countries' previous FMD status and other possible confounders, as well as uncertainty about the 'true' model, and provided accurate predictions (90% specificity and 80% sensitivity). This model represents a novel approach to predicting FMD, and other conditions, on a global scale and in identifying important risk factors that can be applied to global policy and allocation of resources for disease control.     

灰关联聚类分析方法碘乏病防治效果评价中的应用

本文以灰色系统理论为基础,创立了碘缺乏病防治效果评价分析方法,并通过实例证实其评价方法的简洁性、灵活性和有效性,其结论可为指导防治工作提供依据。     

植病经济的内涵与研究方法评述

阐述了植病经济的概念、目标、任务、内涵,并对植病经济的研究方法进行摸索与探讨,其中部分研究方法用实例加以说明,以期为植病经济的深入研究提供借鉴与参考。     

阿尔茨海默病遗传学研究进展

阿尔茨海默病(Alzheimer's disease,AD),以65岁为界可分为早发性(early-onset Alzheimer's disease,EOAD)和晚发性(late-onset Alzheimer's disease,LOAD)两种,其中LOAD占90%以上。两者均是遗传因素和环境因素相互作用的结果,其中LOAD的遗传度高达80%。随着人类基因组计划的完成,全基因组关联研究和二代基因测序技术的进展,一系列基因(BIN1、CLU、ABCA7、CR1、PICALM、MS4A4A/MS4A6A/MS4A4E、EPHA1、CD2AP、CD33)被发现与LOAD的易感性相关。本文综述了与LOAD发病相关的易感基因研究进展。     

小儿先天性心脏病的探查分析

目的:通过彩超对先天性心脏病进行探查、分类,明确诊断,早期治疗。方法:采用美国惠普公司生产的HP7500彩色多普勒超声心动仪与美国GE公司生产的GE vivid7型彩色多普勒超声心动仪,对2008-2010年临床疑诊为先天性心脏病的患儿256例进行检查,检出先天性心脏病患儿210例。结果:检出室间隔缺损83例,占39.5%,室间隔膜部瘤并室缺15例,并房间隔缺损20例。②房间隔缺损55例,占26.1%,③动脉导管未闭38例,占18.9%,④法四15例,占0.07%;⑤心内膜垫缺损9例,占0.04%;⑥永存动脉干3例,占0.014%;⑦三尖瓣闭锁2例,占0.01%;⑧右室双出口2例,占0.01%;⑨原发性肺动脉高压2例,占0.005%;⑩右位心,肺静脉异位引流1例,占0.005%。结论:彩超诊断小儿先天性心脏病准确并且无创,对手术方式的选择和术后评价提供了有价值的临床资料。