Relationship of Length of Obesity to Overall Mortality Risk

This study was conducted to analyze the relationship between the duration of obesity and the risk of death. The results of this study show that the risk of death rises with an increase in the number of years spent while being obese. More deaths were reported due to heart disease, cancer and other causes among those who were obese than those who were never obese. The authors thus conclude that, “The number of years lived with obesity is directly associated with the risk of mortality.”

Numerous studies have shown that those who are obese are at a greater risk of dying from heart disease, cancer and other causes. Studies have revealed that the risk of death among middle-aged individuals who are obese is 22 percent higher compared to similarly aged non-obese individuals. Similarly, the risk of death is 10 percent higher in obese individuals who are over 65 years of age, compared to non-obese individuals of similar age. There is a lack of studies on the change in risk of death in relation to the years spent being obese. The authors of this study speculate that the risk of death could be higher in a person who has been obese for 20 years compared to someone who has been obese for only a year. This study attempted to test this theory.

* This study involved a population comprising of 5036 individuals aged between 28 and 62 years. The participants were assessed every 2 years from 1948 onwards, for a total of 48 years.
* Chronic diseases, other ailments and deaths were recorded. Body Mass Indices were also noted during each health examination.
* The associations between weight, body mass index and deaths due to various chronic diseases and other causes were calculated using the hazard ratio (risk of death).

Key findings
* The hazard ratios for obesity of one to five years, five to 15 years, 15 to 25 years and over 25 years’ duration were found to be 1.51, 1.94, 2.25 and 2.52 respectively, which were higher than those observed for the non-obese individuals.
* The results revealed that for every two years of obesity, the risk of death due to any cause, heart disease, cancer and other diseases were 1.06, 1.07, 1.03 and 1.07, respectively.
* There seemed to be a direct correlation between the years spent in obesity and the risk of death in the population.

Next steps/Shortcomings
According to the authors, this study began in 1948 when the rates of obesity were much lower in the population. A more recent study that prospectively looks at a population over the next few decades is warranted to get a better estimate of the relation between obesity duration and risk of death. Nearly a quarter of the participants could not be assessed for their body mass indices during all their visits. This could also have skewed the results.

This study shows that increase in the duration of obesity can increase the risk of death due to heart disease, cancer and other diseases. Thus, the duration of obesity is found to be a better predictor of risk of death compared to a single measurement of weight or body mass index. This means that if obesity occurs early in life or in childhood, the risk of death also increases exponentially. The authors of this study advise policy makers, strategists and researchers to focus on delaying the onset of obesity. They further add, “It is necessary to take the duration of obesity into consideration when estimating the future health burden associated with current obesity trends.”

For More Information:
The Number of Years Lived with Obesity and the Risk of All-Cause and Cause-Specific Mortality
Publication Journal: International Journal of Epidemiology, 2011
By Asnawi Abdullah; Rory Wolfe; Monash University, Melbourne, Australia and University Muhammadiyah Aceh, Banda Aceh, Indonesia


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