Tackling non-ignorable dropout in the presence of time varying confounding

We explore the sensitivity of time varying confounding adjusted estimates to different dropout mechanisms. We extend the Heckman correction to two time points and explore selection models to investigate situations where the dropout process is driven by unobserved variables and the outcome respectively. The analysis is embedded in a Bayesian framework which provides several advantages. These include fitting a hierarchical structure to processes that repeat over time and avoiding exclusion restrictions in the case of the Heckman correction. We adopt the decision theoretic approach to causal inference which makes explicit the no-regime-dropout dependence assumption. We apply our methods to data from the ‘Counterweight programme’ pilot: a UK protocol to address obesity in primary care. A simulation study is also implemented

How can weight-loss app designers' best engage and support users? A qualitative investigation

This is the peer reviewed version of the article, which has been published in final form at doi: 10.1111/bjhp.12114. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for self-archiving.This study explored young adults' experiences of using e-health internetbased computer or mobile phone applications (apps) and what they valued about those apps.NIH

"They all work...when you stick to them" : a qualitative investigation of dieting, weight loss, and physical exercise, in obese individuals

BackgroundTo explore the extent to which people living with obesity have attempted to lose weight, their attitudes towards dieting, physical exercise and weight loss solutions, why their weight loss attempts have failed, and their opinions about what would be most beneficial to them in their struggle with their weight.MethodQualitative study, using open-ended interviews, of 76 people living with obesity in Victoria, Australia in 2006/7. Individuals with a BMI of 30 or over were recruited using articles in local newspapers, convenience sampling, and at a later stage purposive sampling techniques to diversify the sample. Data analysis was conducted by hand using a constant, comparative method to develop and test analytical categories. Data were interpreted both within team meetings and through providing research participants the chance to comment on the study findings.ResultsWhilst participants repeatedly turned to commercial diets in their weight loss attempts, few had used, or were motivated to participate in physical activity. Friends or family members had introduced most individuals to weight loss techniques. Those who took part in interventions with members of their social network were more likely to report feeling accepted and supported. Participants blamed themselves for being unable to maintain their weight loss or \u27stick\u27 to diets. Whilst diets did not result in sustained weight loss, two thirds of participants felt that dieting was an effective way to lose weight.ConclusionIndividuals with obesity receive numerous instructions about what to do to address their weight, but very few are given appropriate long term guidance or support with which to follow through those instructions. Understanding the positive role of social networks may be particularly important in engaging individuals in physical activity. Public health approaches to obesity must engage and consult with those currently living with obesity, if patterns of social change are to occur

On the Futility of Screening for Genes That Make You Fat

J. Lennert Veerman discusses the implications for genetic screening of findings showing that physical activity substantially attenuates the effects of genetic variants which predispose towards obesity

'For me it's about not feeling like I'm on a diet':a thematic analysis of women's experiences of an intermittent energy restricted diet to reduce breast cancer risk

BACKGROUND: Weight-loss programmes requiring intermittent energy restriction offer an alternative to continuous energy restriction programmes that typically have low adherence. We reported greater weight loss, better adherence and spontaneous reduced energy intake on healthy eating days with intermittent as opposed to continuous energy restriction. The present study aims to explore why intermittent energy restriction diets exert these positive effects. METHODS: Semi-structured interviews were carried out with 13 women aged 39-62 years, who followed a 4-month intermittent energy restriction (2 days of low energy/low carbohydrate, 5 days of healthy eating). Nine of the 13 women successfully lost >5% of their total body weight. Data were analysed using thematic analysis. RESULTS: The intermittent regimen redefined the meaning of dieting and normal eating. Women reconceptualised dieting as only two low energy days per week, even though this often differed from their pre-diet eating patterns. Women reported that they could adhere more closely to the rules of the intermittent diet compared to previously attempted continuous diets. They found that the intermittent diet was less cognitively demanding because the restrictive and clear rules of the intermittent diet were easier to understand and easier to follow than with continuous dieting. CONCLUSIONS: Many participants found intermittent dieting preferable to previous experiences of continuous dieting. The findings provide some insight into the ways in which intermittent dieting is successful, and why it could be considered a viable alternative to continuous energy restriction for weight loss

Has carbohydrate-restriction been forgotten as a treatment for diabetes mellitus? A perspective on the ACCORD study design

Prior to the discovery of medical treatment for diabetes, carbohydrate-restriction was the predominant treatment recommendation to treat diabetes mellitus. In this commentary we argue that carbohydrate-restriction should be reincorporated into contemporary treatment studies for diabetes mellitus

A model of social influence on body mass index

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109867/1/nyas12344.pd

Low-carbohydrate diets for overweight and obesity: a systematic review of the systematic reviews

Low‐carbohydrate diets are being widely recommended, but with apparently conflicting evidence. We have conducted a formal systematic review of the published systematic reviews of RCTs between low‐carbohydrate vs. control (low‐fat/energy‐restricted) diets in adults with overweight and obesity. In MEDLINE, Embase, Web of Knowledge and Cochrane Database of Systematic Reviews, searched from inception to September 2017, we identified 12 systematic reviews, 10 with meta‐analyses. Differences in methods, study quality, weight change and citations of published systematic reviews were assessed by AMSTAR‐2. Review methods varied in definitions of low‐carbohydrate diet, databases searched and bias assessment. Overall review quality was high in two, moderate in three, critically low in seven. Among meta‐analyses, 4/5 with critically low quality showed low‐carbohydrate diet superiority for weight loss (0.7–4.0 kg), while high quality meta‐analyses reported little or no difference between diets. Greater numbers of participants correlated with smaller differences in weight loss (r = 0.73, p = 0.03). More citations correlated with lower review quality (rho = −0.9, p = 0.037), with larger differences in weight loss (rho = −0.9, p = 0.037), and with journal impact factor (rho = 1.0, p = 0.01). In conclusion, publication acceptance and citations appear to favour apparently larger effect sizes above methodological quality. Better quality reviews and RCTs are needed, before recommending low‐carbohydrate diets as preferred to other approaches for energy restriction