Use and cumulation of evidence from modelling studies to inform policy on food taxes and subsidies: biting off more than we can chew?

Abstract Background Food tax-subsidy policies are proposed to hold promise for helping to produce healthier patterns of food purchasing and consumption at population level. Evidence for their effects derives largely from simulation studies that explore the potential effects of untried policies using a mathematical modelling framework. This paper provides a critique first of the nature of the evidence derived from such simulation studies, and second of the challenges of cumulating that evidence to inform public health policy. Discussion Effects estimated by simulation studies of food taxes and subsidies can be expected to diverge in potentially important ways from those that would accrue in practice because these models are simplified, typically static, representations of complex adaptive systems. The level of confidence that can be placed in modelled estimates of effects is correspondingly low, and the level of associated uncertainty is high. Moreover, evidence from food tax-subsidy simulation studies cannot meaningfully be cumulated using currently available quantitative evidence synthesis methods, to reduce uncertainty about effects. Summary Simulation studies are critical for the initial phases of an incremental research process, for drawing together diverse evidence and exploring potential longer-term effects. While simulation studies of food taxes and subsidies provide a valuable and necessary input to the formulation of public health policy in this area, they are unlikely to be sufficient, and policy makers should not place excessive reliance on evidence from such studies, either singly or cumulatively. To reflect known and unknown limitations of the models, results of such studies should be interpreted cautiously as tentative projections. Modelling studies should increasingly be integrated with more empirical studies of the effects of food tax and subsidy policies in practice

Machine learning reduced workload for the Cochrane COVID-19 Study Register: development and evaluation of the Cochrane COVID-19 Study Classifier

BACKGROUND: This study developed, calibrated and evaluated a machine learning (ML) classifier designed to reduce study identification workload in maintaining the Cochrane COVID-19 Study Register (CCSR), a continuously updated register of COVID-19 research studies. METHODS: A ML classifier for retrieving COVID-19 research studies (the 'Cochrane COVID-19 Study Classifier') was developed using a data set of title-abstract records 'included' in, or 'excluded' from, the CCSR up to 18th October 2020, manually labelled by information and data curation specialists or the Cochrane Crowd. The classifier was then calibrated using a second data set of similar records 'included' in, or 'excluded' from, the CCSR between October 19 and December 2, 2020, aiming for 99% recall. Finally, the calibrated classifier was evaluated using a third data set of similar records 'included' in, or 'excluded' from, the CCSR between the 4th and 19th of January 2021. RESULTS: The Cochrane COVID-19 Study Classifier was trained using 59,513 records (20,878 of which were 'included' in the CCSR). A classification threshold was set using 16,123 calibration records (6005 of which were 'included' in the CCSR) and the classifier had a precision of 0.52 in this data set at the target threshold recall >0.99. The final, calibrated COVID-19 classifier correctly retrieved 2285 (98.9%) of 2310 eligible records but missed 25 (1%), with a precision of 0.638 and a net screening workload reduction of 24.1% (1113 records correctly excluded). CONCLUSIONS: The Cochrane COVID-19 Study Classifier reduces manual screening workload for identifying COVID-19 research studies, with a very low and acceptable risk of missing eligible studies. It is now deployed in the live study identification workflow for the Cochrane COVID-19 Study Register

Downsizing: policy options to reduce portion sizes to help tackle obesity.

The worldwide prevalence of obesity and overweight has risen substantially over the past three decades with no country yet achieving a reduction.1 International and national ambitions to “end childhood obesity”2 and “reduce non-communicable diseases by 25% by 2025”3 are unmatched by policiesthat could realise them. The causes of obesity are complex but overconsumption of food and sugary drinksis a critical proximal determinant, driven in part by large portion sizes. The importance of developing interventions and policies to reduce the size, availability, and appeal of large portionsis underscored by the compelling evidence that people eat and drink more from larger portions

Karyotyping human chromosomes by optical and X-ray ptychography methods

Sorting and identifying chromosomes, a process known as karyotyping, is widely used to detect changes in chromosome shapes and gene positions. In a karyotype the chromosomes are identified by their size and therefore this process can be performed by measuring macroscopic structural variables. Chromosomes contain a specific number of base pairs that linearly correlate with their size; therefore it is possible to perform a karyotype on chromosomes using their mass as an identifying factor. Here, we obtain the first images of chromosomes using the novel imaging method of ptychography. We can use the images to measure the mass of chromosomes and perform a partial karyotype from the results. We also obtain high spatial resolution using this technique with synchrotron source X-rays

Personal financial incentives for changing habitual health-related behaviors: A systematic review and meta-analysis.

OBJECTIVES: Uncertainty remains about whether personal financial incentives could achieve sustained changes in health-related behaviors that would reduce the fast-growing global non-communicable disease burden. This review aims to estimate whether: i. financial incentives achieve sustained changes in smoking, eating, alcohol consumption and physical activity; ii. effectiveness is modified by (a) the target behavior, (b) incentive value and attainment certainty, (c) recipients' deprivation level. METHODS: Multiple sources were searched for trials offering adults financial incentives and assessing outcomes relating to pre-specified behaviors at a minimum of six months from baseline. Analyses included random-effects meta-analyses and meta-regressions grouped by timed endpoints. RESULTS: Of 24,265 unique identified articles, 34 were included in the analysis. Financial incentives increased behavior-change, with effects sustained until 18months from baseline (OR: 1.53, 95% CI 1.05-2.23) and three months post-incentive removal (OR: 2.11, 95% CI 1.21-3.67). High deprivation increased incentive effects (OR: 2.17; 95% CI 1.22-3.85), but only at >6-12months from baseline. Other assessed variables did not independently modify effects at any time-point. CONCLUSIONS: Personal financial incentives can change habitual health-related behaviors and help reduce health inequalities. However, their role in reducing disease burden is potentially limited given current evidence that effects dissipate beyond three months post-incentive removal.This research was funded by the Wellcome Trust as part of a Strategic Award in Biomedical Ethics; program title: “The Centre for the Study of Incentives in Health”; grant number: 086031/Z/08/Z; PI Prof. TM Marteau. The funder did not contribute to any part of this research.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.ypmed.2015.03.00

Quasi-experimental study designs series –Paper 9: Collecting Data from Quasi-Experimental Studies

Objective: To identify variables that must be coded when synthesizing primary studies that use quasi-experimental designs.  Study Design and Setting: All quasi-experimental (QE) designs.  Results: When designing a systematic review of QE studies potential sources of heterogeneity – both theory-based and methodological – must be identified. We outline key components of inclusion criteria for syntheses of quasi-experimental studies. We provide recommendations for coding content-relevant and methodological variables, and outlined the distinction between bivariate effect sizes and partial (i.e., adjusted) effect sizes. Designs used and controls employed are viewed as of greatest importance. Potential sources of bias and confounding are also addressed.  Conclusion: Careful consideration must be given to inclusion criteria and the coding of theoretical and methodological variables during the design phase of a synthesis of quasi-experimental studies. The success of the meta-regression analysis relies on the data available to the meta-analyst. Omission of critical moderator variables (i.e., effect modifiers) will undermine the conclusions of a meta-analysis

原著

For the purpose of investigating into the influence which is to be exercised by anaerobic bacteria lodged in the intestines of animals on their hosts, experiments were performed on the influence of Cl. welchii in germ-free chicks. Chicks of white leghorn were hatched in a germ-free environment, in chambers made germ-free by sterilization with steam under normal and high pressures. Germless chicks thus obtained were fed on an autoclaved diet, water and vitamins ; since the fifteenth day after being hatched, certain amount of the organisms of Cl. welchii mixed with autoclaved diet had been given to earth germless chicks. During this period, studies were made on the growth, increase in weight and germicidal power of the sera obtained from them. The results are summarized as follows : (1) An environment better suited for breeding germless chicks was provided by a tank designed to be made germ-free by sterilization with steam under high pressure than by one using normal pressure, with the result that the growth of chicks in the former was better than in the latter. (2) Oral administration of Cl. welchii to germless chicks caused diarrhea to take place and also an increase in weight to stop or a decrease in weight to occur. They, however, began to put on weight again in 5 or 7 days. But examinations carried out after a certain period showed that the increase of their weight was lower by about 50 per cent than the increase of weight of the chicks to which Cl. welchii had not been given (controls). (3) Germicidal power of the sera obtained from germless chicks was very low, while that of the sera obtained from the chicks to which Cl. welchii had been given was markedly high. (4) The results of the present experiments indicate that Cl. welchii, when given orally to germless chicks, may exert harmful influence on the growth of their hosts.The fact, however, that the germicidal power of chicks to which Cl. welchii had been given was higher than that of germless chicks suggests that the presence of this kind of bacteria in the intestines of animals may make the hosts more resistant to infection with other pathogenic organisms than otherwise

Economic instruments for population diet and physical activity behaviour change: a systematic scoping review.

BACKGROUND: Unhealthy diet and low levels of physical activity are common behavioural factors in the aetiology of many non-communicable diseases. Recent years have witnessed an upsurge of policy and research interest in the use of taxes and other economic instruments to improve population health. OBJECTIVE: To assemble, configure and analyse empirical research studies available to inform the public health case for using economic instruments to promote dietary and physical activity behaviour change. METHODS: We conducted a systematic scoping review of evidence for the effects of specific interventions to change, or general exposure to variations in, prices or income on dietary and physical activity behaviours and corollary outcomes. Systematic electronic searches and parallel snowball searches retrieved >1 million study records. Text mining technologies were used to prioritise title-abstract records for screening. Eligible studies were selected, classified and analysed in terms of key characteristics and principal findings, using a narrative, configuring synthesis focused on implications for policy and further research. RESULTS: We identified 880 eligible studies, including 192 intervention studies and 768 studies that incorporated evidence for prices or income as correlates or determinants of target outcomes. Current evidence for the effects of economic instruments and exposures on diet and physical activity is limited in quality and equivocal in terms of its policy implications. Direct evidence for the effects of economic instruments is heavily skewed towards impacts on diet, with a relative lack of evidence for impacts on physical activity. CONCLUSIONS: The evidence-based case for using economic instruments to promote dietary and physical activity behaviour change may be less compelling than some proponents have claimed. Future research should include measurement of people's actual behavioural responses using study designs capable of generating reliable causal inferences regarding intervention effects. Policy implementation needs to be carefully aligned with evaluation planning and design

Crowdsourcing and COVID-19: a case study of Cochrane Crowd

Cochrane has used crowdsourcing effectively to identify health evidence since 2014. To date, over 175,000 trialshave been identified for Cochrane’s Central Register of Controlled Trials via Cochrane Crowd (https://crowd.cochrane.org), Cochrane’s citizen science platform, engaging a Crowd of over 20,000 people from 166 countries. The COVID-19 pandemic presented the evidence synthesis community with the enormous challenge of keeping up with the exponential output of COVID-19 research. This case study will detail the new tasks we developed to aid the production of COVID-19 rapid reviews and supply the Cochrane COVID-19 study register. The pandemic initially looked set to disrupt the Crowd team’s plans for 2020 but has in fact served to further our understanding of the potential role crowdsourcing can play in the health evidence ecosystem

Still moving toward automation of the systematic review process: a summary of discussions at the third meeting of the International Collaboration for Automation of Systematic Reviews (ICASR)

The third meeting of the International Collaboration for Automation of Systematic Reviews (ICASR) was held 17–18 October 2017 in London, England. ICASR is an interdisciplinary group whose goal is to maximize the use of technology for conducting rapid, accurate, and efficient systematic reviews of scientific evidence. The group seeks to facilitate the development and widespread acceptance of automated techniques for systematic reviews. The meeting’s conclusion was that the most pressing needs at present are to develop approaches for validating currently available tools and to provide increased access to curated corpora that can be used for validation. To that end, ICASR’s short-term goals in 2018–2019 are to propose and publish protocols for key tasks in systematic reviews and to develop an approach for sharing curated corpora for validating the automation of the key tasks