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Bad Habits Explain Class Differences in Health: Study

TUESDAY March 23, 2010 -- Unhealthy behaviors -- including higher rates of smoking, poor diets and lack of exercise -- can explain almost three-fourths of the higher death rate among people of lower socioeconomic standing, a new study suggests.

Public health experts have known for decades that poorer people are more likely to die from most causes than the more affluent, explained James Dunn, an associate professor of applied public health at McMaster University in Ontario, Canada.

"That includes suicide, accidents, injuries, poisonings, most cancers, heart disease, strokes, infectious disease -- almost everything that kills us and makes us sick," said Dunn, who wrote an editorial that accompanied the study in the March 24/31 issue of the Journal of the American Medical Association.

What's been up for debate has been the reason why. Some experts blame bad behavior while others blame stressors associated with poverty, such as a lack of control over jobs and housing, fear of violence in neighborhoods or higher exposure to pollutants.

In the study, researchers from France analyzed 24 years of data from the British Whitehall II longitudinal study, which has tracked more than 10,000 British government workers aged 35 to 55 since 1985. Civil servants were divided into three groups based on their job classification: high (administrative), intermediate (professional or executive) and low (clerical or support staff).

Health behaviors, including smoking, alcohol consumption, diet and physical activity, were assessed at four points. At the outset, those in the lower socioeconomic rank were more likely to smoke than those in the highest rank (30 percent vs. 10 percent); be physically inactive (35 percent vs. 7 percent) and eat an unhealthy diet (15 percent vs. 6 percent). Those of lower rank were more likely to abstain from alcohol (36 percent compared to 8 percent), while those of a higher job class were more likely to be heavy drinkers.

Over the course of 24 years, 654 participants died. After controlling for gender and year of birth, those with the lowest rank at work were 1.6 times more likely to die than those with the highest positions.

When measured at a single point in time, differences in behavior could explain 42 percent of the class differences in mortality, the team found and, over time, health behaviors mattered even more, explaining 72 percent of the difference.

"The study shows health behaviors are more important in explaining socioeconomic differences in health than previously thought," Dunn said.

Tracking the impact of behavior over time is important because of substantial changes in people's habits since the 1980s. Smoking rates, for example, have dropped from 30 percent to 17 percent of those of lower socioeconomic rank, while sedentary behavior rose from 35 percent to 42 percent. Obesity rates have also risen dramatically, said study author Silvia Stringhini, a doctoral candidate at the Centre for Research in Epidemiology and Population Health in Villejuif, France.

In the study, all of the workers were employed and had access to health care. Even so, Stringhini said the findings could apply to the United States, where there is a similar link between lower socioeconomic status and mortality.

"In order to reduce health inequalities, health policies should specifically target individuals from lower socioeconomic status," Stringhini said. "Not only do people of high socioeconomic status tend to have better behaviors, but they are also more likely to change their unhealthy behaviors in a positive manner in response to health education messages than their less advantaged counterparts."

Despite the strong influence of behavior, Dunn said it's important not to forget that "multi-overlapping stressors" associated with poverty could both contribute to bad lifestyle choices and higher death rates.

"The reason poorer people have poorer health is because they have poorer behaviors," Dunn said. "It's a reason, but it's not the reason."

Many of the skills required to make better choices, including the ability to self-regulate, or delay gratification and plan ahead, may be strongly influenced by early childhood experiences. Programs to change behavior have to take that into account.

"The takeaway message is that we need much more clever models of health promotion than the classic model of education and enlightenment and expecting people to make a rational choice," Dunn said.

More information

The U.S. Centers for Disease Control and Prevention's Office of Minority Health & Health Disparities has more on the issue.

Posted: March 2010


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