Friday August 26 2011
Many newspapers have reported that half of UK men could be obese by 2030 if trends continue.
The Guardian said that “governments around the world need to make immediate and dramatic policy changes to reverse a pandemic of obesity”. The Independent reported that by 2030 there will be 26 million people in the UK who are obese - a rise of 73% from the current 15 million. The Daily Mail reported that women will be close behind, “with four in ten similarly overweight” by that year.
These news stories and others are based on a series of papers in The Lancet examining issues surrounding the current worldwide obesity ‘pandemic’. The predictions come from one of these studies, which looked at obesity data from the US and UK, which have had the highest obesity levels in the world over the past 20 years. The researchers predict that if the current trend continues, up to 48% of men and 43% of women in the UK could be obese by 2030, adding an additional £1.9-2 billion per year in medical costs for obesity-related diseases.
Modelling studies like this are valuable for alerting governments and health services to potential future scenarios, allowing them to decide what actions are needed. As the authors point out, these projections are merely extrapolations of currently available data, and uncertainties always exist when making predictions as past trends do not always predict future trends. Despite these limitations, this study and others in The Lancet series highlight how obesity is likely to weigh heavily on the country’s healthcare system and economy. How best to target preventative measures at the population level is clearly an important public health priority.
Where did the story come from?
The news stories are based on a series of papers on obesity published today in The Lancet. The papers critically examine what is known about the global obesity ‘pandemic’: its causes, the biology behind weight control and maintenance, the economic and health burden of obesity, and what can be done to reverse the current rise in obesity and the expected rise in obesity-related chronic diseases in the future.
The media has mainly focused on a paper which analysed obesity trends in the US and UK, and their impact on the prevalence of disease and healthcare spending. This paper is the focus of this Behind the Headlines analysis.
The other three papers in the series examine what is causing the global epidemic, as well as the introduction of a new web-based bodyweight simulation model that incorporates the metabolic adaptations that occur as we lose weight. The papers also analyse the interventions needed to halt and reverse the rise in obesity. These papers are not discussed further here.
What kind of research was this?
The paper on obesity trends is a narrative review and modelling study. The authors discuss the threat to population health from the rise in obesity; the health burden resulting from the rise in chronic diseases and the projected rise in healthcare costs as a result of this, and economic costs due to lack of productivity.
The researchers used recent statistics and evidence to create a model predicting the health and economic consequences of obesity in the US and UK over the next 20 years. Making these projections required them to make various assumptions about future trends based on current trends and data. If there is some variation to these trends over the coming decades then these models will be inaccurate. Therefore they can be viewed only as predictions of what might happen based on what is now known.
The specific methodology of how the relevant studies and statistics were obtained for this article is not given. Consequently, it is not possible to comment on whether all relevant data has been considered.
What does the research discuss?
The researchers say that a recent review of data from 199 countries estimated that almost 1½ billion adults worldwide were overweight in 2008. Among them, 502 million were obese. The researchers also say that another report by the Organisation for Economic Co-operation and Development evaluated 11 countries and found that of these the US and UK consistently had the highest prevalence of obesity over the past 20-40 years. The report predicted that this trajectory was likely to continue to 2020.
The paper points out that cardiovascular disease, diabetes and various cancers are the main chronic diseases associated with obesity. Given that the prevalence of these diseases is already rising due to the fact that people are living longer, the extra burden from obesity suggests a substantial cost to the healthcare system. The researchers say that a study estimated that obesity accounts for between 0.7 and 2.8% of a country’s total healthcare costs, and that obese people’s medical costs are 30% higher than those of normal-weight people.
The researchers say that the most recent US data estimated that obese people have 46% higher inpatient costs, 27% more doctor visits and outpatient costs, and 80% greater spending on prescription drugs. By 2030, healthcare costs due to obesity and overweight are projected to account for 16–18% of total US healthcare expenditure.
In the UK, a 2007 report by the Office for Science Foresight Programme projected that the continuing rise in obesity will add £5.5 billion in medical costs to the National Health Service by 2050. In addition to medical costs, society incurs substantial costs from obesity as a result of increased risks of disability and disability pensions, higher work absenteeism and reduced productivity, and increased risk of people retiring early or dying before they reach retirement age.
The researchers say that it is difficult to quantify future healthcare costs resulting from obesity as costs are affected by changing demographics, the economy and the availability of food. However, they say that they used the modelling framework used by the Foresight Programme and applied this to the US and the UK situation to provide updated projections for obesity trends and healthcare expenditure for obesity-related diseases.
What were the main findings?
The model indicated that in the US, past trends in BMI growth project an increase in the prevalence of obesity among adults from about 32% in 2007–08, (the latest available data) to 50–51% in 2030 for men. For women the projected increase is from 35% to 45–52%. From these projections it was estimated that by 2030 there will be an extra 65 million adults in the US who are obese compared to the number in 2010. Of these, 24 million would be aged over 60 years.
In the UK, past trends predicted that by 2030 the prevalence of obesity would rise from 26% to 41-48% in men, and from 26% to 35-43% in women. This would equate to 11 million more obese adults by 2030, 3.3 million of whom would be older than 60.
In both the US and UK, the rise in obesity is expected to be associated with an extra 6 to 8.5 million cases of diabetes, 5.7 to 7.3 million cases of heart disease and stroke, and between 492,000 and 669,000 additional cases of cancer. In addition, the increasing prevalence of debilitating disorders such as osteoarthritis would affect the duration of the person’s healthy lifespan.
Medical costs associated with treatment of these chronic diseases are estimated to increase by $48-66 billion per year in the US, and by £1.9-2 billion per year in the UK by 2030. Regarding economic effects of lost work productivity, the researchers say that the shortage of consistent and high-quality data prevents comparisons between countries. However, using estimates from the US 2008 National Health and Wellness study they estimated that by 2030 there would be a loss of 1.7 – 3 million productive person-years among working-age US adults. This would be associated with an economic cost as high as $390–580 billion.
What were the researchers’ conclusions?
The researchers highlight that excess weight and obesity have significant effects on lifespan, disability, quality of life, and work productivity, with subsequent burdens on population health and healthcare systems. Obesity is known to be associated with various chronic diseases, including diabetes, coronary heart disease, stroke, cancer and osteoarthritis, which impose considerable costs, from the use of healthcare services and medical treatments to the loss of productivity.
The researchers note that the health and economic effects of excess weight and obesity have a protracted time course, and their model has enabled them to link changes in obesity at the population level to disease burdens over the coming decade. They say that a clear understanding of the potential health and cost implications resulting from changes in obesity trends is crucial when choosing the most effective and cost-effective strategies, and how to best target research and funding towards this end.
This study evaluated current statistics on the obesity ‘pandemic’ and predicted rises in healthcare expenditure in the future if things continue to follow their current trend. As the authors highlight, effective policies to promote healthier weight would have clear economic benefits.
The modelling study presents valuable predictions of future trends in excess weight and obesity, which will be useful for governmental and public health planning. However, as the authors themselves highlight, these projections are merely extrapolations of currently available data. Uncertainties always exist when making predictions, as past trends do not always predict future trends. For example, it is not possible to be certain how the current trend will be affected by changes to the economy, demographics, agriculture, food prices, or technological advances. Also, though the study demonstrates a clear rise in expected healthcare expenditure, it is also difficult to accurately predict what cost savings could be expected from a reduction in obesity levels.
The authors also highlight that, though there is some benefit from having access to previous surveys that have consistently used the objective measure of BMI to assess excess weight and obesity, these surveys have not always been nationally representative. For example, these authors used data from the large National Health and Nutrition Examination Survey (NHANES) in the US, which only considers people living in the community; They also used the Healthy Survey for England, which does not cover Wales, Scotland or Northern Ireland. Also, the model was not able to study the future effect of rising childhood obesity.
Despite limitations to projected figures, this study and others in The Lancet series highlight how obesity is likely to weigh heavily on the country’s healthcare system and economy. How best to target preventative measures at the population level is clearly an important public health priority.