The role of a prospective public health intervention study register in building public health evidence: proposal for content and use

Evidence-informed practice is a key component of public health and the focus of much discussion, of which the nature of evidence and how it is best gathered and appraised has formed a large part. Prospective registration of trials is now a key component of rigour and quality in clinical research and has been supported at an international level through the WHO International Clinical Trials Registry Program. This paper discusses the scope and benefits of trial registration in clinical research, including greater transparency and reduced publication bias. It then considers the potential for a Prospective Public Health Intervention Studies Register specific to the needs of public health and aspects to be included in such a register. It is argued that this initiative has the potential to facilitate increased global cooperation and efficiency in the production of high quality evidence and ultimately in improved health outcomes for populations.

Effects of gamma-tocopherol supplementation on thrombotic risk factors

Objective: The antioxidant activity of vitamin E is derived primarily from alpha-tocopherol (α-T) and gammatocopherol (γ-T). Results of epidemiological studies have demonstrated an inverse relationship between vitamin E intake and coronary disease. However, the results of clinical trials using α-T are equivocal. We determined the effect of 5 weeks of 100 mg/d or 200 mg/d γ-T supplementation on thrombotic markers such as platelet reactivity, lipid profile and the inflammation marker C-reactive protein (CRP). Methods and results: Fourteen healthy subjects consumed 100 mg/day while 13 consumed 200 mg/d of γ-T and 12 received placebo (soybean capsules with less than 5 mg/d γ-T) in a double-blinded parallel study design. Fasting pre and post dose blood samples were analysed. Blood γ-T concentrations increased significantly (p<0.05) relative to dose during the intervention period. Both groups receiving active ingredients showed significantly lower platelet activation after supplementation (p<0.05). Subjects consuming 100 mg/d γ-T had significantly decreased LDL cholesterol, platelet aggregation and mean platelet volume (MPV) (p<0.05). Little effect of γ-T was observed on other parameters. Conclusions: These data suggest that γ-T  supplementation may have a permissive role in decreasing the risk of
thrombotic events by improving lipid profile and reducing platelet activity.

Prevention of type 2 diabetes by lifestyle intervention in an Australian primary health care setting : Greater Green Triangle (GGT) Diabetes Prevention Project

Background
Randomised controlled trials demonstrate a 60% reduction in type 2 diabetes incidence through lifestyle modification programmes. The aim of this study is to determine whether such programmes are feasible in primary health care.

Methods
An intervention study including 237 individuals 40–75 years of age with moderate or high risk of developing type 2 diabetes. A structured group programme with six 90 minute sessions delivered during an eight month period by trained nurses in Australian primary health care in 2004–2006. Main outcome measures taken at baseline, three, and 12 months included weight, height, waist circumference, fasting plasma glucose and lipids, plasma glucose two hours after oral glucose challenge, blood pressure, measures of psychological distress and general health outcomes. To test differences between baseline and follow-up, paired t-tests and Wilcoxon rank sum tests were performed.

Results
At twelve months participants' mean weight reduced by 2.52 kg (95% confidence interval 1.85 to 3.19) and waist circumference by 4.17 cm (3.48 to 4.87). Mean fasting glucose reduced by 0.14 mmol/l (0.07 to 0.20), plasma glucose two hours after oral glucose challenge by 0.58 mmol/l (0.36 to 0.79), total cholesterol by 0.29 mmol/l (0.18 to 0.40), low density lipoprotein cholesterol by 0.25 mmol/l (0.16 to 0.34), triglycerides by 0.15 mmol/l (0.05 to 0.24) and diastolic blood pressure by 2.14 mmHg (0.94 to 3.33). Significant improvements were also found in most psychological measures.

Conclusion
This study provides evidence that a type 2 diabetes prevention programme using lifestyle intervention is feasible in primary health care settings, with reductions in risk factors approaching those observed in clinical trials.

Trial Number
Current Controlled Trials ISRCTN38031372

Evidence-based nutrition and cardiovascular disease in the Asia-Pacific region

The Asia-Pacific region is undergoing a major change in both food and health patterns, with a connection between the two more than likely. Evidence for certain traditional Asia-Pacific foods as protective agents against chronic non-communicable disease and cardiovascular disease (CVD), in particular, is growing at a time when their usage diminishes. The nature of the evidence to establish relevant Asia-Pacific food-health linkages will include randomised placebo-controlled clinical trials, but is much more extensive and meaningful. Okinawans have probably achieved one of the most successful food cultures from a health point of view and serve as a reference point for the Asia-Pacific region. The expert working party has produced, in November 2000, the 'Okinawan Recommendations on Nutrition and CVD in the Asia-Pacific region'.

Social structures of science and approaches to outcomes-based medical research

Recently, two seemingly divergent approaches have emerged in outcomes-based medical research. Proponents of evidence-based medicine (EBM) argue that the most effective treatments will be found by adopting a hierarchical approach that gives pre-eminence to randomized controlled clinical trials, where these are available. Proponents of participatory medical research argue that research undertaken with consumers and other partners in the community will produce the best outcomes. While one approach marginalizes consumer experience the other approach draws consumers into it. EBM assumes a high level of consensus in a scientific community, while participatory medical research relies on co-opting consumer experience. This paper indicates that each approach involves a particular view of social structure in science. The paper uses theories of social relations among scientists for the purpose of critically assessing EBM and the participatory model.

Interventions for preventing obesity in children (Review)

Background
Obesity prevention is an international public health priority. The prevalence of obesity and overweight is increasing in child populations throughout the world, impacting on short and long-term health. Obesity prevention strategies for children can change behaviour but efficacy in terms of preventing obesity remains poorly understood.

Objectives
To assess the effectiveness of interventions designed to prevent obesity in childhood through diet, physical activity and/or lifestyle and social support.

Search strategy
MEDLINE, PsycINFO, EMBASE, CINAHL and CENTRAL were searched from 1990 to February 2005. Non-English language papers were included and experts contacted.

Selection criteria
Randomised controlled trials and controlled clinical trials with minimum duration twelve weeks.

Data collection and analysis
Two reviewers independently extracted data and assessed study quality.

Main results
Twenty-two studies were included; ten long-term (at least 12 months) and twelve short-term (12 weeks to 12 months). Nineteen were school/preschool-based interventions, one was a community-based intervention targeting low-income families, and two were family-based interventions targeting non-obese children of obese or overweight parents.

Six of the ten long-term studies combined dietary education and physical activity interventions; five resulted in no difference in overweight status between groups and one resulted in improvements for girls receiving the intervention, but not boys. Two studies focused on physical activity alone. Of these, a multi-media approach appeared to be effective in preventing obesity. Two studies focused on nutrition education alone, but neither were effective in preventing obesity.

Four of the twelve short-term studies focused on interventions to increase physical activity levels, and two of these studies resulted in minor reductions in overweight status in favour of the intervention. The other eight studies combined advice on diet and physical activity, but none had a significant impact.

The studies were heterogeneous in terms of study design, quality, target population, theoretical underpinning, and outcome measures, making it impossible to combine study findings using statistical methods. There was an absence of cost-effectiveness data.

Authors' conclusions
The majority of studies were short-term. Studies that focused on combining dietary and physical activity approaches did not significantly improve BMI, but some studies that focused on dietary or physical activity approaches showed a small but positive impact on BMI status. Nearly all studies included resulted in some improvement in diet or physical activity. Appropriateness of development, design, duration and intensity of interventions to prevent obesity in childhood needs to be reconsidered alongside comprehensive reporting of the intervention scope and process.

Early childhood caries: current evidence for aetiology and prevention

Background: Despite the fact that it is largely preventable, dental caries (decay) remains one of the most common chronic diseases of early childhood. Dental decay in young children frequently leads to pain and infection necessitating hospitalization for dental extractions under general anaesthesia. Dental problems in early childhood have been shown to be predictive of not only future dental problems but also on growth and cognitive development by interfering with comfort nutrition, concentration and school participation. Objective: To review the current evidence base in relation to the aetiology and prevention of dental caries in preschool-aged children. Methods: A search of MEDLINE, CINALH and Cochrane electronic databases was conducted using a search strategy which restricted the search to randomized controlled trials, meta-analyses, clinical trials, systematic reviews and other quasi-experimental designs. The retrieved studies were then limited to articles including children aged 5 years and under and published in English. The evidence of effectiveness was then summarized by the authors. Conclusions: The review highlighted the complex aetiology of early childhood caries (ECC). Contemporary evidence suggests that potentially effective interventions should occur in the first 2 years of a child's life. Dental attendance before the age of 2 years is uncommon; however, contact with other health professionals is high. Primary care providers who have contact with children well before the age of the first dental visit may be well placed to offer anticipatory advice to reduce the incidence of ECC.