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Size does matter: why large-scale research is a must for public health

Data from over a quarter of a million individuals add up to provide a window on the population. Malkolm - Bust it Away Photography/Flickr

Researchers are becoming increasingly intrigued by the idea that too much sitting is bad news for health, and a landmark Australian paper published today in Archives of Internal Medicine has dealt yet another body blow to our sedentary lifestyles.

This research has important public health implications, not least because of what it has found: standing up more often is associated with a lower chance of dying within three years – even if you’re already physically active.

Our research team found that adults who sat 11 or more hours each day had a 40% increased risk of dying in the next three years compared with those who sat for fewer than four hours a day. We reached these figures after taking into account physical activity, weight and health status.

This is one of the few studies to focus on the link between total sitting time and death from all causes. But just as critical is its size – we studied more than 200,000 people to get our results.

Big is beautiful

Getting access to such a large number of people would normally involve a herculean research effort – and a lot of dollars. But seven years ago, Australia launched its first large-scale, long-term study of people aged over 45 to help address this problem.

The idea was to create a shared research resource, and the end result was the 45 and Up Study. The study involves more than a quarter of a million men and women, who’ve agreed to share ongoing information about their health and lifestyles, and have it linked to their Medicare and Pharmaceutical Benefits Scheme data, hospitalisations and general practice use, and other health-related databases.

Such a pooled resource means researchers don’t need to reinvent the wheel every time they want to conduct research relevant to this population. It costs less because the labour- and resource-intensive business of recruiting participants is already taken care of. It’s also quicker to conduct big studies – if researchers don’t have to focus on securing funding and collecting the data, they can spend more time devising innovative research programs, analysing and reporting their results. Large-scale data also provide greater statistical reliability.

And there’s less of a burden on those taking part. Once they have given their information, there’s little else for them to do. But this data can be used across multiple projects, meaning the return on their initial time investment – the bang for their buck if you like – is high.

Paving the way

Large-scale, long-term research is not new. Britain’s Million Women Study and the US Nurses’ Health Study are just two examples of big league cohort studies that will continue to yield answers that are important to population health for years.

Australia also has form in this area. The Busselton Health Study in Western Australia has surveyed 16,000 people since 1966, and has been relied on by local and international researchers. It has resulted in more than 300 research articles being published. Other, later examples include the Australian Longitudinal Study of Women’s Health and the Melbourne Collaborative Cohort Study.

What 45 and Up gives us, is a specific avenue to better understand the impact of our ageing population and chronic disease, as increased demand continues to stretch our limited health services and resources. Its large-scale, collaborative model, basis in the general population, and use of linked health data provide a uniquely powerful combination for population health research.

Linked information opens many doors for researchers, including allowing them to form new research collaborations with colleagues from a wide range of disciplines. The collaborative research model at the heart of 45 and Up ensures data from participants are used to the full. This is not always the case in research studies – though that’s not widely acknowledged.

Privacy issues

There are obvious privacy issues to consider and all data collected is de-identified. The study, also bound by Commonwealth and State privacy legislation and guidelines, is independently monitored and answerable to an ethics committee. Each research project using study data must demonstrate it’s in the public interest with the potential to provide information to improve health.

Managed by the Sax Institute, 45 and Up is a collaboration with Cancer Council New South Wales, the National Heart Foundation of Australia (NSW Division), NSW Health, beyondblue, NSW Department of Family and Community Services and the Australian Red Cross Blood Service. So it needs to satisfy the ethical and professional requirements of all of these organisations.

Jon Fife

The sitting time research paper published today is one of 60 research sub-studies underway using 45 and Up data. They are uncovering new knowledge in areas, such as the connection between breastfeeding and reduced risk of diabetes, links between obesity and sleep, and causes of early retirement.

Bright futures

Altruism appears to be a driving factor among the 267,000 people who have agreed to give us their information. When we ask participants what motivated them to take part, they say things like this: “When I realised that the Study would establish a database to better manage health in the future I thought … imagine if we had done that 100 years ago.”

This year, during our first five-year follow up, we will be talking to our quarter of a million participants again. We have also agreed to collaborate with the Million Women Study, allowing researchers to compare the performance of the Australian and UK health systems.

Being willing to share their experiences means participants give us a “window on the population”. There is endless scope to mine this rich research resource, which will grow in value over time. Many of the answers to some of our most pressing national health problems are at our fingertips. We just have to know the right questions to ask.

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