Age-specific changes in BMI and BMI distribution among Australian adults using cross-sectional surveys from 1980 to 2008

Background: Research efforts have focused mainly on trends in obesity among populations, or changes in mean body mass index (BMI), without consideration of changes in BMI across the BMI spectrum. Examination of age-specific changes in BMI distribution may reveal patterns that are relevant to targeting of interventions.

Methods: Using a synthetic cohort approach (which matches members of cross-sectional surveys by birth year) we estimated population representative annual BMI change across two time periods (1980 to 1989 and 1995 to 2008) by age, sex, socioeconomic position and quantiles of BMI. Our study population was a total of 27 349 participants from four nationally representative Australian health surveys; Risk Factor Prevalence Study surveys (1980 and 1989), the 1995 National Nutrition Survey and the 2007/8 National Health Survey.

Results: We found greater mean BMI increases in younger people, in those already overweight and in those with lower education. For men, age-specific mean annual BMI change was very similar in the 1980s and the early 2000s (P=0.39), but there was a recent slowing down of annual BMI gain for older women in the 2000s compared with their same-age counterparts in the 1980s (P<0.05). BMI change was not uniform across the BMI distribution, with different patterns by age and sex in different periods. Young adults had much greater BMI gain at higher BMI quantiles, thus adding to the increased right skew in BMI, whereas BMI gain for older populations was more even across the BMI distribution.

Conclusions: The synthetic cohort technique provided useful information from serial cross-sectional survey data. The quantification of annual BMI change has contributed to an understanding of the epidemiology of obesity progression and identified key target groups for policy attention—young adults, those who are already overweight and those of lower socioeconomic status.

A suite of visual languages for model-driven development of statistical surveys and services

Objective: To provide statistician end users with a visual language environment for complex statistical survey design and implementation. Methods: We have developed, in conjunction with professional statisticians, the Statistical Design Language (SDL), an integrated suite of visual languages aimed at supporting the process of designing statistical surveys, and its support environment, SDLTool. SDL comprises five diagrammatic notations: survey diagrams, data diagrams, technique diagrams, task diagrams and process diagrams. SDLTool provides an integrated environment supporting design, coordination, execution, sharing and publication of complex statistical survey techniques as web services. SDLTool allows association of model components with survey artefacts, including data sets, metadata, and statistical package analysis scripts, with the ability to execute elements of the survey design model to implement survey analysis. Results: We describe three evaluations of SDL and SDLTool: use of the notation by expert statistician to design and execute surveys; useability evaluation of the environment; and assessment of several generated statistical analysis web services. Conclusion: We have shown the effectiveness of SDLTool for supporting statistical survey design and implementation. Practice implications: We have developed a more effective approach to supporting statisticians in their survey design work.

Accounting for uncertainty in volumes of seabed change measured with repeat multibeam sonar surveys

Seafloors of unconsolidated sediment are highly dynamic features; eroding or accumulating under the action of tides, waves and currents. Assessing which areas of the seafloor experienced change and measuring the corresponding volumes involved provide insights into these important active sedimentation processes. Computing the difference between Digital Elevation Models (DEMs) obtained from repeat Multibeam Echosounders (MBES) surveys has become a common technique to identify these areas, but the uncertainty in these datasets considerably affects the estimation of the volumes displaced. The two main techniques used to take into account uncertainty in volume estimations are the limitation of calculations to areas experiencing a change in depth beyond a chosen threshold, and the computation of volumetric confidence intervals. However, these techniques are still in their infancy and, as a result, are often crude, seldom used or poorly understood. In this article, we explored a number of possible methodological advances to address this issue, including: (1) using the uncertainty information provided by the MBES data processing algorithm CUBE, (2) adapting fluvial geomorphology techniques for volume calculations using spatially variable thresholds and (3) volumetric histograms. The nearshore seabed off Warrnambool harbour - located in the highly energetic southwest Victorian coast, Australia - was used as a test site. Four consecutive MBES surveys were carried out over a four-months period. The difference between consecutive DEMs revealed an area near the beach experiencing large sediment transfers - mostly erosion - and an area of reef experiencing increasing deposition from the advance of a nearby sediment sheet. The volumes of sediment displaced in these two areas were calculated using the techniques described above, both traditionally and using the suggested improvements. We compared the results and discussed the applicability of the new methodological improvements. We found that the spatially variable uncertainty derived from the CUBE algorithm provided the best results (i.e. smaller confidence intervals), but that similar results can be obtained using as a fixed uncertainty value derived from a reference area under a number of operational conditions.

Diagnosing autism: Australian paediatric research network surveys

AIM: Autism spectrum disorder (ASD) is a neurodevelopmental disorder with reported prevalence of more than 1/100. In Australia, paediatricians are often involved in diagnosing ASD and providing long-term management. However, it is not known how paediatricians diagnose ASD. This study aimed to investigate whether the way Australian paediatricians diagnose ASD is in line with current recommendations. METHODS: Members of the Australian Paediatric Research Network were invited to answer questions about their ASD diagnostic practice in a multi-topic survey and also as part of a study about parents needs around the time of a diagnosis of ASD. RESULTS: The majority of the 124 paediatricians who responded to the multi-topic survey and most who responded to the parent needs survey reported taking more than one session to make a diagnosis of ASD. Most paediatricians included information from preschool, child care or school when making a diagnosis, and over half included information from speech pathology or psychology colleagues more than 50% of the time. The main reasons for not including assessment information in the diagnostic process were service barriers such as no regular service available or long waiting lists. More than 70% reported ordering audiology and genetic tests more than half of the time. CONCLUSION: Not all paediatricians are following current recommendations for diagnosing ASD more than 50% of the time. While there are good reasons why current diagnostic approaches may fall short of expected standards, these need to be overcome to ensure diagnostic validity and optimal services for all children and their families.

Short form health surveys and related variants in spinal cord injury research : a systematic review

CONTEXT: 'Short Form' health surveys - such as the SF-36 and SF-12 - are widely used in medical research. Spinal cord injury (SCI) is no exception, despite oft-cited concerns regarding measurement properties for populations with physical impairment.OBJECTIVE: To provide a comprehensive overview of the use of Short Form health surveys and their variants within the SCI literature.METHODS: Papers published between database inception and September 2012 were identified from 11 electronic databases; a supplementary reference list search was also conducted. Data extraction focused on details regarding the range of different Short Form surveys and variants used in SCI research, the respective frequency of use, the nature of reporting (complete versus partial reporting) and the method of survey administration.RESULTS: One hundred seventy-four papers were identified. Thirty-six-item Short Form health surveys were frequently administered as complete instruments (n = 82); in 69 of these 82 studies (84%), it was not clearly stated which 36-item version had been used (e.g. SF-36v1, SF-36v2, RAND-36). Data for individual items and domains were often reported (29% of identified studies), indicating significant partial use of standardized measures. Modified variants of standardized health surveys were administered in 12 studies.CONCLUSION: Although standardized Short Form health surveys are common within SCI research, attempts to add, delete, or modify items have resulted in a number of variants, often with minimal supportive psychometric evidence. Using established, generic outcome measures is appealing for a number of reasons. However, validity is paramount and requires further explicit consideration within the SCI research community.

Hunting Plato's agalmata

In this essay I argue that to understand Plato's philosophy, we must understand why Plato presented this philosophy as dialogues: namely, works of literature. Plato's writing of philosophy corresponds to his understanding of philosophy as a transformative way of life, which must nevertheless present itself politically, to different types of people. As a model, I examine Lacan's famous reading of Plato's Symposium in his seminar of transference love in psychoanalysis. Unlike many other readings, Lacan focuses on Alcibiades' famous description of what caused his desire for Socrates: the supposition that beneath Socrates' Silenus-like language and appearance, there were agalmata, treasures, hidden in his belly. I argue that this image of Socrates can also stand as an image for how we ought to read and to teach Plato's philosophy: as harbouring different levels of insight, couched in Plato's philosophy as literature.