Impact numbers: measures of risk factor impact on the whole population from case-control and cohort studies

Objective: To describe new measures of risk from case-control and cohort studies, which are simple to understand and relate to numbers of the population at risk. Design: Theoretical development of new measures of risk. Setting: Review of literature and previously described measures. Main results: The new measures are: (1) the population impact number (PIN), the number of those in the whole population among whom one case is attributable to the exposure or risk factor (this is equivalent to the reciprocal of the population attributable risk),- (2) the case impact number (CIN) the number of people with the disease or outcome for whom one case will be attributable to the exposure or risk factor (this is equivalent to the reciprocal of the population attributable fraction); (3) the exposure impact number (EIN) the number of people with the exposure among whom one excess case is attributable to the exposure (this is equivalent to the reciprocal of the attributable risk); (4) the exposed cases impact number (ECIN) the number of exposed cases among whom one case is attributable to the exposure (this is equivalent to the reciprocal of the aetiological fraction). The impact number reflects the number of people in each population (the whole population, the cases, all those exposed, and the exposed cases) among whom one case is attributable to the particular risk factor. Conclusions: These new measures should help communicate the impact on a population, of estimates of risk derived from cohort or case-control studies.

Alcohol, tobacco and breast cancer - collaborative reanalysis of individual data from 53 epidemiological studies, including 58 515 women with breast cancer and 95 067 women without the disease

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58515 women with invasive breast cancer and 95067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19 - 1.45, P < 0.00001) for an intake of 35 - 44 g per day alcohol, and 1.46 (1.33 - 1.61, P < 0.00001) for greater than or equal to 45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P

'Vigilant Hospitality': The Online Imperative and Teaching Cultural Studies

Information technology (IT) sees information as a fluid, to be stored, regulated and exchanged. This is a profoundly economic model, whose dreams are those of the marketplace – and now, university managers. But no teacher, of course, holds that teaching can be reduced to the movement of information from one point to another. Teaching is never quite absorbed into the models of IT. Where they meet, we do not have the utopia of the virtual classroom, at last freed from the strictures of timetables and the face-to-face; we have, rather, the grinding of two radically irreducible models. This has nothing to do with Luddism; on the contrary, it is the value and necessity of IT for us at present, as teachers. At a time when the tertiary sector’s massive investment in IT is motivated in part by its own dream of the teacherless classroom, one of the pressing tasks for us may be simply to argue as rigorously as we can the structural necessity of our own position as teachers, without nostalgia or humanist sentimentality.

Adapting immunity with subunit vaccines: case studies with group A Streptococcus and malaria

Although vaccines have widely been regarded as the most cost-effective way to improve public health, for some organisms new technological advances in vaccine design and delivery, incurring additional developmental costs, will be essential. These organisms are typically those for which natural immunity is either slow to develop or does not develop at all. Clearly, such organisms have evolved strategies to evade immune responses and innovative approaches will be required to induce a type of immune response which is both different to that which develops naturally and is effective. This article describes some approaches to develop vaccines for two such organisms (malaria parasites and Streptococcus pyogenes (group A Streptococcus)) that are associated with widespread mortality and morbidity, mostly in the poorest countries of the world. At this stage, the challenges are primarily scientific, but if these hurdles are surmounted then the challenges will become financial ones - developing much needed vaccines for people least able to afford them. (C) 2002 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.

Biochemical and molecular studies using human autopsy brain tissue

The use of human brain tissue obtained at autopsy for neurochemical, pharmacological and physiological analyses is reviewed. RNA and protein samples have been found suitable for expression profiling by techniques that include RT-PCR, cDNA microarrays, western blotting, immunohistochemistry and proteomics. The rapid development of molecular biological techniques has increased the impetus for this work to be applied to studies of brain disease. It has been shown that most nucleic acids and proteins are reasonably stable post-mortem. However, their abundance and integrity can exhibit marked intra- and intercase variability, making comparisons between case-groups difficult. Variability can reveal important functional and biochemical information. The correct interpretation of neurochemical data must take into account such factors as age, gender, ethnicity, medicative history, immediate ante-mortem status, agonal state and post-mortem and post-autopsy intervals. Here we consider issues associated with the sampling of DNA, RNA and proteins using human autopsy brain tissue in relation to various ante- and post-mortem factors. We conclude that valid and practical measures of a variety of parameters may be made in human brain tissue, provided that specific factors are controlled.