Four risk factors reducing U.S. life expectancy

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A new study from researchers at the Harvard School of Public Health and the Institute for Health Metrics and Evaluation at the University of Washington suggests that four preventable risk factors—high blood pressure, smoking, high blood sugar and overweight/obesity—are significantly reducing life expectancy across the U.S. In the new study, published this week in the Public Library of Science open-access journal PLoS Medicine, researchers estimate that the combined influence of these avoidable risks reduces life expectancy by 4.9 years in men, and 4.1 years in women.

Yet beyond the study’s broad implications for how these preventable health problems may be limiting life expectancy across the entire U.S. population, researchers also examined how their impact differed in different ethnic and geographic groups. As in previous studies, the team of researchers categorized the U.S. population into “Eight Americas,” or groups distinguished by common ethnic, socioeconomic and regional factors. The eight groups include: Asians; rural low-income whites from the northern plains and Dakotas; low-income whites from Appalachia and the Mississippi Valley; Native Americans from Western plains or mountain areas, mostly living on or near reservations; “Middle America,” or basically all whites, Asians and Native Americans not included in other groups; low-income rural blacks from the Deep South; high-risk urban blacks (living in counties with high rates of homicide); and “Black Middle America,” or all blacks not included in other groups.

Researchers then analyzed 2005 health data from the National Center for Health Statistics, and large discrepancies between groups became apparent. While Asians had the lowest reduction in life expectancy due to these four preventable risk factors, Southern, low-income rural blacks had the highest: high blood pressure, overweight, high blood sugar and smoking contributed to a reduction in life expectancy of 4.1 years among Asian men and 3.6 years among Asian women, compared with 6.7 years for men and 5.7 years for women in the Southern low-income rural black group. Additionally, individual risk factors varied greatly across the different “Americas.” According to the findings, for example, Western Native American men and Southern black women had the highest body mass index (BMI) of the groups studied, while Asians had the lowest BMI. Blacks in all “Americas” tended to have higher blood pressure than other ethnic groups, but this was particularly true among blacks from the rural Deep South. And smoking was most prevalent among Western Native Americans and low-income whites living in Appalachia and the Mississippi Valley, with nearly one third of both men and women smoking.

The findings suggest that by targeting these four risk factors Americans across the different eight groups studied could substantially improve life expectancy, notably reducing death caused by heart disease and cancers related to these risk factors. Yet, to achieve those goals, the researchers argue, it is important to first evaluate what hasn’t been working about our current public health strategies, and “identify, implement, and rigorously evaluate effective population-based and personal interventions that can reduce these preventable risk factors and mitigate their effects on disease outcomes.” Public health officials should take a lesson from failed anti-obesity efforts, the authors argue, which emphasize “the need to develop and test new creative and ambitious interventions.”