Weight History Could Identify Increased Risk of Early Death.

A patient’s weight history could help identify their risk of dying prematurely, according to a new study led by School of Public Health researchers.

The study, published online at JAMA Network Open, found that an obese classification based on body mass index (BMI) at any point in adulthood was associated with increased risk of all-cause mortality. The researchers saw a 21.9 percent increased risk of death for each 5-unit increase in a person’s lifetime maximum BMI.

“This study highlights the importance of eliciting weight history in clinical practice for identifying patients at increased risk of death, and the importance of obesity prevention,” says senior author Ching-Ti Liu, associate professor of biostatistics.

Liu and his colleagues used data from 6,197 participants of the BU-based Framingham Heart Study, one of the world’s longest-running studies on cardiovascular disease. The researchers examined the weight history of the participants over 24 years, a period in which 3,478 of the participants died.

They found an association between an individual’s maximum BMI and risk of all-cause mortality, with those whose BMI was ever in the obese range being the most likely to have died in the 24-year period. For participants whose maximum BMI was above the CDC-defined normal range, they found a 27 percent increased risk of death for each 5-unit increase in maximum BMI.

The researchers also found that death from cardiovascular disease was the most strongly associated with higher BMI, although they also observed significant associations with other causes of death.

“A silver lining of our results is that the association of obesity with all-cause mortality appeared to decline over the last few decades,” says study co-author Andrew Stokes, assistant professor of global health.

One possible explanation for the finding, Stokes says, is that the study spanned a period where cardiovascular disease mortality declined substantially in the US thanks to improved drug therapies, risk factor control, and other improvements, possibility contributing to reductions in the risks associated with obesity.

The study is part of a body of research that undercuts the so-called “obesity paradox” raised by prior studies suggesting being overweight can lead to greater survival rates among certain groups of people. Recently, Stokes and colleagues found that looking at weight history over a lifetime, instead of a single weight measurement, did show an association between obesity and higher mortality.

The study was led by doctoral student Hanfei Xu and co-authored by L. Adrienne Cupples, professor of biostatistics.

—Michelle Samuels