Number of obese years – not just obesity – risk for heart damage

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In an analysis of clinical data collected on more than 9,000 people, Johns Hopkins researchers have shown that the number of years spent overweight or obese appear to “add up” to a distinct risk factor for heart damage. Those with a longer history of being heavy were more likely to test positive for a chemical marker of so-called “silent” heart damage than people with a shorter history of overweight.

The findings suggest that maintaining a healthy weight across the lifespan is important for keeping the heart healthy and minimizing damage as people age.

People’s weight from age 25 onwards is linked to the risk of more or less heart damage, as measured by levels of the protein troponin, later in life, which underscores the likely importance of long-term weight control for reducing heart disease risk. The findings suggest that even in the absence heart disease risk factors such as high blood pressure, diabetes or kidney disease, the number of years spent obese or overweight contributes to the higher likelihood of heart damage.

About the study

For the study, the research team used data gathered on 9,062 participants in Atherosclerosis Risk in Communities (ARIC) study in Washington County, Maryland, Forsyth County, North Carolina, Jackson, Mississippi, and Minneapolis.

Participants were followed four times over nine to 11 years to assess body mass index (BMI), history of heart disease and blood level of troponin. Participants also self-reported their weight at age 25, which provided information on weight from young adulthood through late middle age and elderly years. The average age of participants at the fourth visit was 63.

Elevated troponin more likely in people who became overweight, obese

Nearly 23 percent of participants had an increase in BMI from the first visit to the fourth visit. At the fourth visit, 3,748 participants were overweight and 3,184 were obese. Some 5 percent showed a decreased BMI and 72 percent remained the same.

At the fourth visit, almost 7 percent of the participants had increased levels of troponin. Those who increased in BMI to the overweight and obesity range at the fourth visit were 1.5 times more likely to have increased troponin levels of at least 14 nanograms per liter, indicating heart damage.

The experts then looked at the BMI at the beginning and end of the study period alongside participants’ troponin levels. Those people who were obese at both the first and fourth visits were twice as likely as those with persistently normal weight to have increased troponin levels to more than 14 nanograms per liter. Those with obesity at both the fourth visit and at age 25 were almost four times more likely to have increased troponin levels.

For each 10 years that a person spent obese, their risk of having elevated troponin increased 1.25 times, even when accounting for heart disease risk factors.

The researchers said there is some evidence that losing weight even after decades of obesity or being overweight may help reduce troponin levels and that the heart has the ability to heal somewhat, but the extent to which it can heal and the number of years spent obese that may cause permanent damage are unknown and require more study.

Source: Clinical Chemistry, January 2018.

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