Early in 1999, the AOA commissioned its first formal study, a new analysis of the cost of obesity to the health care system in the United States. The AOA retained The Lewin Group, an internationally recognized firm that evaluates the economics of diseases and treatments for the U.S. government, managed care organizations and pharmaceutical companies. The results of the study were announced at AOA’s Conference on September 15, 1999.
The Lewin Group approached the topic by examining all health care costs associated with treating adults with obesity. Its analysis differed from previous studies by taking into account the costs of co-morbid diseases and other medical costs.
Robert Rubin, M.D., president of The Lewin Group and lead investigator for the study, began the investigation with a review of 29 co-morbid conditions associated with obesity. In consultation with a panel of the AOA board and advisory council, Dr. Rubin determined that 15 of the co-morbid conditions were scientifically well established to be a result of obesity. Those conditions include arthritis, breast cancer, heart disease, colorectal cancer, type 2 diabetes, endometrial cancer, end-stage renal disease, gallbladder disease, hypertension, liver disease, low back pain, renal cell cancer, obstructive sleep apnea, stroke, and urinary incontinence. The other 14 co-morbid conditions were excluded due to an unclear association between obesity and a condition, or the lack of data on the cost or prevalence of a condition.
The Lewin Group utilized data from the National Health Interview Survey (1995) and the third National Health and Nutrition Examination Survey (1988-1994) for the analysis. Direct costs were identified through secondary literature and information provided by professional health associations. Costs were translated into 1999 dollars using the Medical Consumer Price Index. The direct healthcare cost for treating the 15 co-morbid conditions in adults from all Body Mass Index (BMI) categories is $331 billion.
The direct healthcare cost for treating the 15 co-morbid conditions incurred by adults with obesity (BMI > 30) is $102.2 billion. This figure was obtained by multiplying the direct cost of each condition by the percentage of obese patients treated for the co-morbidity and then summing the cost for all 15 conditions. The $102.2 billion figure represents approximately 30% of the direct costs of treating the 15 co-morbidities in adults of all BMI categories. Of the $102.2 billion, approximately 30% is attributed to heart disease, 20% to diabetes, 9% to hypertension, 8% to stroke, 7% to arthritis, 5% to cancer and 21% to the other conditions.
The study confirmed the strong relationship of obesity to several co-morbid conditions, and the increased health risk accompanied by higher BMI’s. Compared to persons at a BMI <25, a person with a BMI >35 has over a six-fold risk of type 2 diabetes, over a five-fold risk of gallstones, over three times the risk of hypertension, nearly three times the risk of arthritis, and nearly twice the risk of stroke.
Individuals with obesity also experience health conditions, which are not related to their obesity. To determine the total economic cost of obesity beyond the scope of the 15 co-morbidities, The Lewin Group incorporated the costs of providing medical services to persons with obesity for non-obesity related health conditions.
Using the estimated total direct healthcare costs of adults from all BMI categories, for all conditions and services in 1999 ($936 billion), the direct healthcare costs of non-obesity related conditions were calculated at $605 billion ($936 billion -$331 billion = $605 billion). Since 22.5% of the population is obese, 22.5% was multiplied against $605 billion, arriving at a cost of $136.1 billion -- the cost attributed to the health impact of obesity on non-co-morbidities. By adding $136.1 billion to the cost of treating obesity co-morbidities ($102.2 billion), the total direct health care costs for all conditions of adults with a BMI > 30 was computed to $238.3 billion.
