Obesity May Not Increase Risk of Death as Patients Age
The association between obesity and mortality becomes weaker with age, according to a recent study. These findings contradict those of a previous study that had reported this association strengthens with age.
Using data from the National Health Interview Survey, the researchers calculated age-specific hazard ratios (HRs) of mortality for grade 2/3 obesity relative to a body mass index (BMI) of 18.5 kg/m2 to less than 25 kg/m2. Obesity was defined as a BMI of at least 35 kg/m2.
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A flexible parametric survival model (n = 240,184 white men) and Cox proportional hazard models (n = 51,697 matched pairs) were implemented in calculating HRs.
Results of the study indicated that HRs appeared to increase with age if the interaction terms between obesity and age at the survey were ignored. This occurred when age at the time of the survey was fixed as a single value. However, after recalculating the results for adults with various ages at the time of the survey, HRs were higher for younger adults vs older adults with the same duration of follow-up. Matched data also indicated that HRs were higher for adults aged 40 to 49 years (2.14) than for adults aged 90 years or older (1.22).
“For any given follow-up duration, the association between obesity and mortality weakens with age,” the researchers concluded. “The previously reported strengthening of the obesity-mortality association with increasing age was caused by the failure to take all the model specifications into consideration when calculating adjusted hazard ratios.”
—Christina Vogt
Reference:
Wang Z, Peng Y, Liu M. Age variation in the association between obesity and mortality in adults. Obesity. 2017;25(12):2137-2141. doi:10.1002/oby.21976.