Large Study Finds Inequality Increases Risk of Premature Death on Par with Unhealthy Behaviors

Suggests focus on inequality should be similar to that on lifestyle risk factors

by Hank Dart

A large, new study has found that income inequality contributes to premature death on a level similar to important lifestyle factors like smoking, physical inactivity, and diabetes.

The study, appearing in The Lancet, combined findings from 48 cohort studies in high-income countries and included over 1.7 million men and women.  Its goal was to assess the impact of socioeconomic status (SES) alongside key lifestyle factors included in the World Health Organization’s (WHO) 25 x 25 initiative.

The WHO created the 25 x 25 initiative in 2011, with the goal of reducing premature deaths from non-communicable diseases, like heart disease and cancer, by 25 percent by 2025.  The initiative targets seven major risk lifestyle factors: smoking, diabetes, physical inactivity, excessive drinking, high blood pressure, overweight, and salt intake.

The study included each of these lifestyles factors, except salt intake, which was not measured in enough of the combined studies to be included in the analyses.  Income and socioeconomic status (SES) were estimated through a person’s occupation, a measure available across the 48 studies.  The three main occupation levels were:  high (e.g., managers, higher professionals), intermediate (e.g., farmers, lower supervisors), and low (e.g., sales workers, semi-skilled/unskilled workers).

The researchers found that low socioeconomic status (SES) increased the risk of premature death from all causes by 26 percent compared to high SES.  This was greater than the impact of overweight and close to the impact of physical inactivity (28 percent increase), high alcohol intake (36 percent increase), and high blood pressure (31 percent increase).  Diabetes increased the risk of premature mortality 73 percent, and smoking more than doubled risk.  The findings controlled for the potential interrelation of SES with the lifestyle risk factors.

When looking at the potential impact population wide, the rankings of the risk factors included in the study shifted a bit, with inequality coming just after smoking and physical inactivity in importance.  The researchers calculated the percent of premature deaths that could be avoided if everyone in the population had a low-risk level of each factor – for example, if inequality were eliminated and everyone had a high-earning occupation, if everyone exercised, and if everyone avoided smoking.

Doing this, they found that low SES accounted for 15 percent of premature deaths in women and 19 percent in men.  This falls not too far behind smoking (21 percent in women, 29 percent in men) and physical inactivity (23 percent in women, 26 percent in men) and in front of the other lifestyle factors included in the study (see figure).

Too often, factors like inequality and socioeconomic status are left out of prevention planning – viewed as health factors that cannot be modified.  This study, however, adds to the evidence that inequality has an independent and important impact on health and that reducing inequality should be a key goal of efforts to improve individuals’, and the nation’s, health — right alongside efforts focused on limiting smoking, increasing physical activity, and controlling weight.  

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