Objectives: To examine the utility of intra-individual variability of reaction times (IIV RT ) and mean reaction time (RT) as behavioural markers of incident all-cause dementia. Design: Longitudinal cohort study followed biennially for four years. Setting

Intraindividual variability of reaction time (IIV RT ), a proposed cognitive marker of neurobiological disturbance, increases in old age, and has been associated with dementia and mortality. The extent to which IIV RT is an independent predictor of mortality, however, is unclear. This study investigated the association of IIV RT and all-cause mortality while accounting for cognitive level, incident dementia and biomedical risk factors in 861 participants aged 70-90 from the Sydney Memory and Ageing Study. Participants completed two computerised reaction time (RT) tasks (76 trials in total) at baseline, and comprehensive medical and neuropsychological assessments every 2 years. Composite RT measures were derived from the two tasks-the mean RT and the IIV RT measure computed from the intraindividual standard deviation of the RTs (with age and time-on-task effects partialled out). Consensus dementia diagnoses were made by an expert panel of clinicians using clinical criteria, and mortality data were obtained from a state registry. Cox proportional hazards models estimated the association of IIV RT and mean RT with survival time over 8 years during which 191 (22.2%) participants died. Greater IIV RT but not mean RT significantly predicted survival time after adjusting for age, sex, global cognition score, cardiovascular risk index and apolipoprotein ε4 status. After excluding incident dementia cases, the association of IIV RT with mortality changed very little. Our findings suggest that greater IIV RT uniquely predicts shorter time to death and that lower global cognition and prodromal dementia in older individuals do not explain this relationship.

Introduction:There is a lack of evidence around the risk of transfusion following vaginal birth after cesarean (VBAC) compared with elective repeat cesarean section (ERCS); this is important for decision-making about birth options. The aim of this study was to determine transfusion rates and risk of transfusion following intended VBAC and ERCS. Material and methods: Women with a primary cesarean who had a subsequent birth at term (≥37 weeks) in New South Wales between 2000 and 2012, were identified from the New South Wales Perinatal Data Collection. Blood transfusions were identified from linked hospital records. Women deemed ineligible for VBAC were excluded. Modified Poisson regression was used to determine transfusion risk associated with intended VBAC compared with ERCS. Intended mode of birth was classified as: (1) intended VBAC and vaginal birth, (2) intended VBAC and cesarean, (3) intended ERCS and (4) "intention uncertain".Results: A total of 90 439 women were eligible for VBAC. Rates of transfusion were:1.4% for intended VBAC and vaginal birth (n = 17 849); 1.2% for intended VBAC and cesarean (n = 7648); 0.3% for intended ERCS (n = 60 471); and 1.1% for "intention uncertain" (n = 4471). After adjusting for maternal and pregnancy characteristics, risk of transfusion was almost four times higher for women classified as intended VBAC than intended ERCS (adjusted risk ratio = 3.73, 95% confidence interval 2.90-4.78). Conclusions:Following a prior primary cesarean, there was a higher risk of transfusion associated with attempting VBAC compared with ERCS. Though the absolute risk is small, it is important for women considering VBAC to choose birthing facilities with ready access to blood products. K E Y W O R D S blood transfusion, intended mode of birth, postpartum hemorrhage, primary cesarean, vaginal birth after cesarean | 383 PONT eT al.

Our objective was to describe patterns and predictors of sedentary behavior (sitting time) over 10 years among a large Canadian cohort. Data are from the Canadian Multicentre Osteoporosis Study, a prospective study of women and men randomly selected from the general population. Respondents reported socio-demographics, lifestyle behaviors and health outcomes in interviewer-administered questionnaires; weight and height were measured. Baseline data were collected between 1995 and 1997 (n = 9418; participation rate = 42%), and at 5- (n = 7648) and 10-year follow-ups (n = 5567). Total sitting time was summed across domain-specific questions at three time points and dichotomized into “low” (≤ 7 h/day) and “high” (> 7 h/day), based on recent meta-analytic evidence on time sitting and all-cause mortality. Ten-year sitting patterns were classified as “consistently high”, “consistently low”, “increased”, “decreased”, and “mixed”. Predictors of sedentary behavior patterns were explored using chi-square tests, ANOVA and logistic regression. At baseline (mean age = 62.1 years ± 13.4) average sitting was 6.9 h/day; it was 7.0 at 5- and 10-year follow-ups (p for trend = 0.12). Overall 23% reported consistently high sitting time, 22% consistently low sitting, 14% decreased sitting, 17% increased sitting with 24% mixed patterns. Consistently high sitters were more likely to be men, university educated, full-time employed, obese, and to report consistently low physical activity levels. This is one of the first population-based studies to explore patterns of sedentary behavior (multi-domain sitting) within men and women over years. Risk classification of sitting among many adults changed during follow-up. Thus, studies of sitting and health would benefit from multiple measures of sitting over time.

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