Smoking, high blood pressure, and being overweight or obese are responsible for the largest number of preventable deaths in the United States, research shows. The study, The preventable causes of death in the United States: comparative risk assessment of dietary, lifestyle, and metabolic risk factors, is the most comprehensive assessment to date of the link between mortality and modifiable risk factors in the US, and the only one to include the effects of dietary, lifestyle, and metabolic risk factors. Earlier studies have quantified deaths linked to only a few factors, such as smoking and alcohol. The work was done in collaboration with scientists at Harvard University and the University of Toronto.
Of the 2.5 million Americans who died in 2005, tobacco smoking was responsible for the deaths of 1 in 5, high blood pressure killed 1 in 6, and overweight-obesity and physical inactivity took 1 in 10 lives. The dietary risks with the largest mortality effects were high dietary salt, low dietary omega-3 fatty acids, and high dietary trans fatty acids.
Most deaths attributable to the risk factors were from cardiovascular diseases. For instance, the data showed high blood pressure was responsible for 45% of all cardiovascular deaths, with overweight-obesity, physical inactivity, high low-density lipoprotein (LDL) cholesterol, smoking, high dietary salt, high dietary trans fatty acids, and low dietary omega 3 fatty acids also contributing significantly to cardiovascular disease. Smoking had the largest effect on cancer mortality, causing an estimated 33% of all cancer deaths. Cancers, respiratory diseases, diabetes, and injuries accounted for nearly 1 in 4 deaths of all deaths caused by smoking, alcohol use, high blood glucose, physical inactivity, low intake of fruits and vegetables, and overweight-obesity.
When breaking the risk factors down by gender, the study shows that high blood pressure was the leading cause of death in women (231,000), accounting for 19% of all female deaths, while smoking was the leading cause of death in men (248,000), responsible for 21% of all male deaths.
Study researchers used data on risk factor exposures in the US population from nationally representative health surveys and disease-specific mortality statistics from the National Center for Health Statistics. They obtained the etiological effects of risk factors on disease-specific mortality, by age, from systematic reviews and meta-analyses of epidemiological studies that had adjusted for major potential confounders and , where possible, for regression dilution bias. They also estimated the number of disease-specific deaths attributable to all nonoptimal levels of each risk factor exposure, by age and sex.
By measuring the impact of a broad range of modifiable risk factors on mortality, IHME intends to help guide investments in interventions that can help reduce key risk factors responsible for premature deaths.
Recommendations for future work
The researchers offer a number of recommendations for future work. For example, future analyses, both in epidemiological cohorts and at the population level, should examine the individual and combined effects of multiple exposures that affect the same diseases, including how much of the effects of lifestyle and dietary risks are mediated through metabolic factors. Additionally, future research should attempt to investigate time-dependent effects of blood glucose, body mass index, physical activity, and dietary factors, because their exposures have changed in the US over time. There is also a need for national and even subnational analysis of the health consequences of dietary, lifestyle, and metabolic risks in countries at different levels of development using local exposure data.
Despite the availability of interventions, blood pressure and tobacco smoking decline in the US have stagnated or even reversed, and there has been a steady increase in overweight-obesity. Research, implementation, monitoring, and evaluation related to interventions that reduce these modifiable risk factors should be a high priority.
Read the technical appendix.
Danaei G, Ding EL, Mozaffarian D, Taylor B, Rehm J, Murray CJL, Ezzati M. The Preventable Causes of Death in the United States: Comparative Risk Assessment of Dietary, Lifestyle, and Metabolic Risk Factors. PLoS Medicine. 2009 Apr 28, 2009; 6(4):e1000058.