A comprehensive assessment of the risk factors for preventable deaths in the United States has found that smoking and high blood pressure are responsible for the greatest number of preventable deaths – each accounting for around 1 in 5 deaths in US adults. The study, published in the open-access journal PLoS Medicine this week, finds that other dietary, lifestyle and metabolic risk factors also cause a substantial number of deaths in the United States.
Majid Ezzati, of the Harvard School of Public Health, and colleagues estimated the number of preventable deaths caused by twelve selected risk factors. These are factors related to lifestyle, including smoking and physical inactivity, dietary factors, such as high salt intake and low intake of fruit and vegetables, and metabolic factors that often result from diet and lifestyle but may also have clinical interventions such as high blood pressure and blood glucose. They are known as “modifiable risk factors” because although it is well established that these risk factors shorten a person’s life expectancy through the increased risk of heart disease, stroke, cancers, and other chronic diseases, they can also be changed or controlled by individuals themselves or through public health as well as medical interventions.
Previous studies had indicated that some lifestyle risk factors are responsible for a huge number of premature deaths in the United States. But Ezzati and colleagues used a more comprehensive method that estimated the number of deaths across different risk factors, including dietary and metabolic factors that had been left out of previous analyses. They devised a “comparative risk assessment” – an estimate of the number of deaths that would be prevented if the distribution of the lifestyle, dietary and metabolic risk factors were at a hypothetical optimum (e.g. if nobody smoked). Gathering data on the risk factors from nationally representative surveys that had already been conducted, they obtained information on deaths from the US National Center for Health Statistics. Of the 2.5 million US deaths in 2005, the researchers estimated that almost 470,000 were associated with tobacco smoking and nearly 400,000 with high blood pressure. Being overweight or obese accounted for nearly 1 in 10 deaths of US adults, whilst high salt intake was responsible for 1 in 25 deaths of US adults - the most of any of the dietary factors analyzed.
The analysis suggests that by targeting a few risk factors there is great potential to reduce the number of preventable deaths in the United States. Importantly, the authors stress that there are interventions at an individual and a population level that are already shown to be effective at combating the two deadliest risk factors in the United States – smoking and high blood pressure. Yet despite knowledge of these interventions, the reduction of blood pressure and tobacco smoking has stagnated and even reversed in some areas.
Comparable information on lifestyle, diet and metabolic risk factors is crucial for forming health policy and priorities, and Ezzati and colleagues conclude by suggesting that “research, implementation, monitoring and evaluation related to interventions” is crucial to reduce the number of preventable deaths in the United States and elsewhere.