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 one person may value a particular outcome differently than another person, these measures capture how each respondent views his or her own quality of life.
The 1993-2008 Behavioral Risk Factor Surveillance System (BRFSS), the largest ongoing state-based health survey of US adults, has conducted interviews of 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.
From 1993 to 2008, when the proportion of smokers among US 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% and this resulted in 0.0464 QALYs lost. Smoking had a bigger impact on deaths while obesity had a bigger impact on illness.
The authors explain that, "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."
Citation: Haomiao Jia, Erica I. Lubetkin,'Trends in Quality-Adjusted Life-Years Lost Contributed by Smoking and Obesity' American Journal of Preventive Medicine, February 2010, 38(2)