Research & Service

As the U.S. population becomes increasingly obese while smoking rates continue to decline, obesity has become an equal, if not greater, contributor to the burden of disease and shortening of healthy life in comparison to smoking. In an article published in the February 2010 issue of the American Journal of Preventive Medicine, researchers from Columbia University and The City College of New York calculate that the Quality-Adjusted Life Years (QALYs) lost due to obesity is now equal to, if not greater than, those lost due to smoking, both modifiable risk factors. QALYs use preference-based measurements of Health-Related Quality of Life (HRQOL) which allow a person to state a relative preference for a given health outcome. Since individuals may value a particular outcome differently, these measures capture how each respondent views his or her own quality of life. The article, “Trends in Quality-Adjusted Life-Years Lost Contributed by Smoking and Obesity,” is authored by the Mailman School’s Haomiao Jia, PhD, assistant professor of clinical Biostatistics (in nursing) and Mailman School alumna Erica I. Lubetkin, MD, MPH ’99 of the Department of Community Health and Social Medicine, Sophie Davis School of Biomedical Education at The City College of New York.

The 1993–2008 Behavioral Risk Factor Surveillance System (BRFSS), the largest ongoing state-based health survey of U.S. adults, has conducted interviews with more than 3,500,000 individuals; annual interviews started with 102,263 in 1993 and culminated with 406,749 in 2008. This survey includes a set of questions that measures HRQOL, asking about recent poor health days and tracking overall physical and mental health of the population. The authors analyzed these data and converted the measures to QALYs lost due to smoking and obesity.

Quality-adjusted life-years lost per adult contributed by obesity and smoking, the obesity rate, and the smoking rate from 1993 to 2008

From 1993 to 2008, when the proportion of smokers among U.S. adults declined 18.5%, smoking-related QALYs lost were relatively stable at 0.0438 QALYs lost per population. During the same period, the proportion of obese people increased 85%, resulting in 0.0464 QALYs lost. Smoking had a bigger impact on deaths while obesity had a bigger impact on illness.

Investigators Jia and Lubetkin state, “Although life expectancy and QALE have increased over time, the increase in the contribution of mortality to QALYs lost from obesity may result in a decline in future life expectancy. Such data are essential in setting targets for reducing modifiable health risks and eliminating health disparities.”