Managing a Low-Incidence Risk: The Example of Toxic Shock Syndrome

This article demonstrates a methodology that allows individuals to reach a personal decision on the use of products which carry very small risks to health and life but also offer considerable benefits. A combination of the principles of dominance, extended dominance, and various methods of direct risk-benefit tradeoffs are shown to reduce the number of possible decisions regarding product use to the one optimal for the value structure of a particular individual. An historical examination of toxic-shock syndrome identifies tampons as a product with risks too small to warrant public intervention but too sizeable to be ignored. The methodology described here can be applied for all such products.     

The Protective Impact of a Covariate on Competing Failures with an Example from a Bone Marrow Transplantation Study

Starting from an applied Bone Marrow Transplantation(BMT) study, the problem of “unexpected protectivity” in competing risks models is introduced, which occurs when one covariate shows a protective impact not expected from a medical perspective. Current explanations found in the statistical literature suggest that unexpected protectivity might be due to the lack of independence between the competing failures. Actually, in the presence of dependence, the Kaplan-Meier curves are not interpretable. Conversely, the cumulative incidence curves remain interpretable, and therefore seem to be a candidate for solving the problem. We discuss the particular nature of dependence in a competing risks framework and illustrate how this dependence may be created via a common frailty factor. A Monte Carlo experiment is set up which accounts also for the association between the observable covariates and the frailty factor. The aim of the experiment is to understand whether and how the bias showed by the estimates could be related to the omitted frailty variable. The results show that dependence alone does not cause false protectivity, and that the cumulative incidence curves suffer the same bias as the survival curves and therefore do not seem to be a solution to false protectivity. Conversely, false protectivity may occur according to the magnitude and the sign of the dependence between the frailty factor and the covariate. The paper ends with some suggestions for empirical research. This revised version was published online in July 2006 with corrections to the Cover Date.     

Estimating the association parameter for copula models under dependent censoring

Summary. Many biomedical studies involve the analysis of multiple events. The dependence between the times to these end points is often of scientific interest. We investigate a situation when one end point is subject to censoring by the other. The model assumptions of Day and co-workers and Fine and co-workers are extended to more general structures where the level of association may vary with time. Two types of estimating function are proposed. Asymptotic properties of the proposed estimators are derived. Their finite sample performance is studied via simulations. The inference procedures are applied to two real data sets for illustration.     

A comparison study of realtime fatality rates: severe acute respiratory syndrome in Hong Kong, Singapore, Taiwan, Toronto and Beijing, China

Summary.  In an outbreak of a completely new infectious disease like severe acute respiratory syndrome (SARS), estimation of the fatality rate over the course of the epidemic is of clinical and epidemiological importance. In contrast with the constant case fatality rate, a new measure, termed the 'realtime' fatality rate, is proposed for monitoring the new emerging epidemic at a population level. A competing risk model implemented via a counting process is used to estimate the realtime fatality rate in an epidemic of SARS. It can capture and reflect the time-varying nature of the fatality rate over the course of the outbreak in a timely and accurate manner. More importantly, it can provide information on the efficacy of a certain treatment and management policy for the disease. The method has been applied to the SARS data from the regions affected, namely Hong Kong, Singapore, Toronto, Taiwan and Beijing. The magnitudes and patterns of the estimated fatalities are virtually the same except in Beijing, which has a lower rate. It is speculated that the effect is linked to the different treatment protocols that were used. The standard estimate of the case fatality rate that was used by the World Health Organization has been shown to be unable to provide useful information to monitor the time-varying fatalities that are caused by the epidemic.     

A Frailty Model in Crossover Studies with Time-to-Event Response Variable

In this article, we develop a model to study treatment, period, carryover, and other applicable effects in a crossover design with a time-to-event response variable. Because time-to-event outcomes on different treatment regimens within the crossover design are correlated for an individual, we adopt a proportional hazards frailty model. If the frailty is assumed to have a gamma distribution, and the hazard rates are piecewise constant, then the likelihood function can be determined via closed-form expressions. We illustrate the methodology via an application to a data set from an asthma clinical trial and run simulations that investigate sensitivity of the model to data generated from different distributions.     

The Attitude of the Shari'a Courts to Parental Alienation Syndrome: Understanding the Dynamics of the Syndrome in Arab Society

In addition to the many factors leading to parental alienation syndrome (PAS), including the narcissistic injury felt by the abandoned parent, or the custodial parent's personal difficulty, there are further factors unique to Arab society—including strong influence by the extended family on the child. Although all the components of PAS exist and are well known to the shari'a courts, no parallel concept is found in the Arab legal lexicon. This article presents 1 case of a shari'a court hearing that illustrates this phenomenon. The conclusions indicate that the shari'a court considers this a serious phenomenon and sees coping with the situation as an essential and preliminary condition to the custody hearing.     

Suicidal Ideation and Comorbid Disorders in Adolescents and Young Adults Diagnosed with Asperger's Syndrome: A Population at Risk

ABSTRACT

The purpose of this study was to examine the level of suicidal ideation and comorbid disorders (major depressive disorder, generalized anxiety disorder) among adolescents and young adults with diagnosed Asperger's syndrome (AS). A cross-sectional study using a self-administrated mail questionnaire and a Web-based questionnaire were used. Two samples were selected for this study. The first sample used snowball sampling, starting with parents of adolescents and young adults with diagnosed AS who participated in a qualitative study conducted in 2002. The second sample consisted of a volunteer sample of parents who visited Web sites for parents and individuals with diagnosed autism spectrum disorder. The sample included 10 adolescents and young adults with diagnosed AS. Fifty percent of the sample had a clinically significant level of suicidal ideation, 20% met criteria for a diagnosis of major depressive disorder, and 30% met criteria for generalized anxiety disorder.     

Child Abuse Prevention During Infancy: Intervention Implications for Caregivers' Attitudes Toward Emotion Regulation

Increasing numbers of states are in the process of passing laws requiring all new parents to receive educational materials to prevent shaken baby syndrome (SBS). These laws create powerful opportunities to reach large numbers of families with an important prevention effort. Results from the effort to raise SBS awareness described here indicate that not only is the content of SBS prevention (e.g., consequences of shaking; emotion regulation/coping skills; safety planning) an important consideration; so too is the approach any given prevention program utilizes. By incorporating social work theory on family-centered practice, social workers, home visitors, and other prevention professionals strengthen the likelihood of having a meaningful impact on caregivers' safe strategies for coping with the frustrations of caring for an infant.     

Variables That Differentiate Chronic Fatigue Syndrome from Depression

Abstract

Assessment for chronic fatigue syndrome (CFS) has depended primarily on information obtained through clinical interviews or questionnaire data. The present study used an activity log, which describes patterns of daily behavior, over the course of two days to examine whether differences existed in the pattern, intensity, and qualitative nature of activity among those with CFS, Major Depressive Disorder (MDD) and controls. On average, participants in the CFS group spent significantly more time resting than the MDD group or control group. The CFS group spent nearly 2.5 times more than the MDD group and 4 times more than the control group performing low intensity activity. Findings indicated that people with CFS feel fatigued more of the time, find activity to be fatiguing more of the time, and need more rest during activity than people with MDD or healthy controls.