Obesity is filling in for smoking as a cause of death in working class women, concluded researchers after reviewing mortality rates from a nearly 30-year study in Scotland.
In Europe, wealthier people either aren’t starting to smoke or are finding it easier to quit, which accounts for up to 85% of the observed differences in mortality between population groups, researchers noted.
Their analysis showed higher rates of being overweight or obese among those who’d never smoked in all occupational classes, with the highest rates in women from lower occupational classes. Almost 70% of the women in the lower occupational classes who had never smoked were overweight or obese, and severe obesity was seven times more prevalent than among smokers in higher social positions. Among women who had never smoked, lower social position was associated with higher mortality rates from cardiovascular disease but not cancer.
To investigate the relations between causes of death, social position and obesity in women who had never smoked, Scottish researchers conducted a prospective cohort study. They drew from the Renfrew and Paisley Study, a long term prospective community based cohort named for two neighboring towns in west central Scotland from which all residents then aged between 45 and 64 were invited to participate from 1972 to 1976.
Researchers reported their results online June 28 in BMJ.
From the study, researchers identified 3,613 women had never smoked. They were categorized by occupational class (I and II, III non-manual, III manual, and IV and V) and body-mass index (normal weight, overweight, moderately obese, and severely obese).
Women in lower occupational classes who had never smoked had poorer lung function and higher systolic blood pressure than women in the higher occupational classes. Overall, 43% (n=1,555) were overweight, 14% (n=515) were moderately obese, and 5% (n=194) were severely obese. Obesity rates were higher in lower occupational classes and much higher in all occupational classes than in current smokers in the full cohort.
In terms of mortality, half (51%; n=916) the women died from cardiovascular disease and more than one-fourth (27%; n=487) from cancer. Relative to occupational class I and II, all cause mortality rates were more than a third higher in occupational classes III manual (relative rate [rr], 1.35; 95% confidence interval [CI]1.16 to 1.57) and IV and V (rr, 1.34; 95% CI 1.17 to 1.55). These were largely explained by differences in obesity, systolic blood pressure, and lung function.
The authors concluded “Because smokers have on average lower body-mass indices but higher mortality rates, it is only when never smokers are analyzed separately that the true impact of obesity on mortality becomes clear.”
An editorialist suggested that obesity is overtaking the health care benefits of smoking cessation. But there is still a gain: “Exchanging smoking for obesity is a good bargain, but inequalities in mortality will not necessarily become smaller. Inequalities in mortality persist among those who have never smoked, partly because obesity takes over the role of smoking, but they persist at a much lower level, and that is good news for whoever wants to reduce health inequalities.”
*This blog post was originally published at ACP Internist*