Adjusting for time-varying confounding in the subdistribution analysis of a competing risk

Despite decades of research in the medical literature, assessment of the attributable mortality due to nosocomial infections in the intensive care unit (ICU) remains controversial, with different studies describing effect estimates ranging from being neutral to extremely risk increasing. Interpretation of study results is further hindered by inappropriate adjustment (a) for censoring of the survival time by discharge from the ICU, and (b) for time-dependent confounders on the causal path from infection to mortality. In previous work (Vansteelandt et al. Biostatistics 10:46–59), we have accommodated this through inverse probability of treatment and censoring weighting. Because censoring due to discharge from the ICU is so intimately connected with a patient’s health condition, the ensuing inverse weighting analyses suffer from influential weights and rely heavily on the assumption that one has measured all common risk factors of ICU discharge and mortality. In this paper, we consider ICU discharge as a competing risk in the sense that we aim to infer the risk of ‘ICU mortality’ over time that would be observed if nosocomial infections could be prevented for the entire study population. For this purpose we develop marginal structural subdistribution hazard models with accompanying estimation methods. In contrast to subdistribution hazard models with time-varying covariates, the proposed approach (a) can accommodate high-dimensional confounders, (b) avoids regression adjustment for post-infection measurements and thereby so-called collider-stratification bias, and (c) results in a well-defined model for the cumulative incidence function. The methods are used to quantify the causal effect of nosocomial pneumonia on ICU mortality using data from the National Surveillance Study of Nosocomial Infections in ICU’s (Belgium).     

Would a Commodity‐based Trade Approach Improve Market Access for Africa? A Case Study of the Potential of Beef Exports from Communal Areas of Namibia

Market access for African livestock products has long been stymied by a variety of animal diseases endemic in the region. The concept of commodity‐based trade (CBT) has been advanced to make trade dependent on process‐related attributes of production that ensure freedom from disease rather than the geographical origin of the animals themselves. This article looks at the potential of CBT in improving market access for beef from communal areas of Namibia, which have historically been excluded from high‐value export markets. Model results suggest only modest gains from CBT, given the substantial costs of compliance with SPS and quality standards required for high‐value markets. Regional markets may still offer the best option for beef exports from these areas.     

The educational experiences of young people with sickle cell disorder: a commentary on the existing literature

Sickle cell disorder (SCD) is a chronic illness that in England disproportionately affects marginalized ethnic groups, but has yet to feature extensively within educational or disability research. This review of existing literature makes the case for a sustained developmental research programme around SCD, disability and education. There are potentially life-saving decisions that could be made by teachers in caring for a child with SCD. The place of the school as a venue for health screening with respect to vision, hearing and dental care is also complicated by SCD. The lack of a formal school policy to address the combined episodic and longer term school absences correlated with SCD clearly disadvantages a group of pupils whose academic potential may already have been curtailed by teacher expectations based on their ethnicity. Both the physical and social milieu of the school could be adapted so that the environmental triggers of severe painful episodes associated with SCD are greatly reduced. Systems of pastoral care and health education elements of the school curriculum need to be attuned to the challenges and opportunities for learning that SCD raises. SCD may be considered as a resource for education across a range of national curriculum subjects, could bring an anti-racist dimension to subjects such as mathematics, biology, history and geography and could challenge a number of prevailing disabling and racist discourses in wider society. In short, SCD could be one bridge to more inclusive education for pupils of marginalized ethnic groups.     

ONE PERSPECTIVE ON THE MILAN SYSTEMIC APPROACH: PART II. DESCRIPTION OF SESSION FORMAT,INTERVIEWING STYLE AND INTERVENTIONS*

The Milan method of working with families includes a number of unique innovations. Among these are a pattern of creative teamwork that clearly separates the cognitive constructions of the therapist in contrast to the belief systems of the family, a style of interviewing that releases information latent in the family, and some novel interventions that facilitate the family's capacity to discover its own non-symptomatic solutions.     

Strangers meet: Laughter and nonverbal signs of interest in opposite-sex encounters

When strangers of the opposite-sex meet for the first time, both sexes are in a difficult situation. In this high risk situation, neither person knows the intention of the other, and consequently non-verbal signalling becomes the major channel for communication. Because of their higher biological risk, females should prefer less obvious tactics in order to communicate interest in a potential partner than males. The tactical task of signalling clearly, but at the same time subtly, is solved by the use of multifunctional or metacommunicative signals. In this study we propose that there is not one single meaning for any given signal. In laughing loudly we find a signal which consists of acoustical, mimical and postural information. In this way either laughter can send a this is play message or its meaning can be modified by other signals. Thus laughter, together with its accompanying body postures and movements, conveys messages that range from sexual solicitation to aversion, depending on which and how many different signals are present. Males seem to communicate interest for the female during laughter with only a few signals, such as body orientation and dominance signals. In contrast, females communicate interest via numerous signals which function as signals of bodily self-presentation and submission. In both sexes, a lack of interest is communicated through closed postures.Polly Wiessner, Jay Feierman and John Dittami have significantly helped with their ideas and have corrected what the author thought was the English language.     

Where Deer Roam: Chronic Yet Acute Site Exposures Preclude Ecological Risk Assessment

Global positioning system (GPS) technology has made possible the detailed tracking of the spatial movements of wildlife. Using GPS tracking collars placed on female white‐tailed deer (Odocoileus virginianus) over a protracted period, we illustrate that this species is spatially irrelevant for consideration in ecological risk assessments (ERAs) for commonly assessed contaminated sites. Specifically, deer movements do not allow for a sufficiency of chemical exposures to occur such that toxicological endpoints would be triggered. Deer are spatially irrelevant not only because their home ranges and overall utilized areas dwarf prototypical hazardous waste sites. They are also inappropriate for assessment because they only minimally contact reasonably sized preferred locations, this while demonstrating a confounding high degree of site affinity for them. Our spatial movements analysis suggests that deer introduce the ERA novelty of a species displaying elements of both chronic and acute site exposure. We further suggest that other large commonly assessed high‐profile mammals could also be found to be spatially irrelevant for ERAs were they to submit to the GPS tracking and subsequent data analysis we performed for the deer. Recognizing that certain receptors need not be considered in ERAs can help to simplify the ERA process.