This article is more than 5 years old. Information may no longer be current.
Measuring BMI in overweight range may not present full assessment of patients’ health
Click Here to Manage Email Alerts
Using BMI as the sole determinant of weight classification may not present a complete picture of a patient’s health or mortality risk, according to a scientific advisory from the American Heart Association.
According to the authors of the recent advisory, results from studies linking BMI in the overweight range and mortality have been mixed. Data from NHANES have suggested that population-wide increases in BMI levels were observed as early as the late 1970s, and modern NHANES data have suggested that about two-thirds of adults in the United States are either overweight (29%) or obese (37%). In addition, many clinical studies have linked obesity with increased risk for mortality.
While many studies have found an association between increased BMI and mortality, the data have not suggested as strong an association in overweight patients. Those results have also been criticized for either methodological or conceptual problems such as lack of statistical power, choice of reference groups, selection bias and even the utility of using BMI as a measurement in certain patients. BMI, as the authors noted, is a surrogate measurement and does not precisely quantify the distribution of body fat in an individual or other measurements, such as waist-to-hip ratio.
Variables such as sex, race, ethnicity and body fat distribution can further complicate the nature of the association between increased BMI and mortality. The authors also said that the focus on total mortality when assessing BMI often “misses a larger picture of the [effect] of excess body weight on health.”
Being overweight is more frequently associated with CHD or CVD mortality than with all-cause mortality and is also associated with the incidence of CVD risk factors like type 2 diabetes, dyslipidemia and systemic hypertension. Other studies have suggested a two- to threefold greater risk for venous thromboembolism among the obese, with some evidence suggesting a similar trend in the overweight population as well.
“There is considerable evidence that being overweight is related to increased risk of other important adverse outcomes besides total mortality,” the authors concluded. “It is critical to consider the overall risk status of patients regardless of BMI, with the realization that those with CVD risk factors such as type 2 diabetes and systemic hypertension are at particularly increased risk from excess weight and may well benefit from weight loss intervention as part of their treatment.”
Lewis C. Circulation. 2009;doi:10.1161/CIRCULATIONAHA.109.192574.