October 31, 2011

Obesity and depression independently increase health costs

Even without depression, obesity  raises health costs in Group Health study

Seattle, WA—Obesity and depression both dramatically increase health care costs, but they mainly  act separately, according to a study published in the November 2011 Journal of General Internal  Medicine by Group Health Research Institute scientists. Gregory Simon, MD, MPH, a Group Health psychiatrist and Group Health Research  Institute senior investigator, led the research.

“Previous research shows that both depression and obesity are associated with higher health care costs,” he said. “But depression and obesity often occur  together, so it was important to know if the relationship between obesity and  cost is really due to depression—or vice versa.”

Simon and his colleagues tested  whether depression confounds the increase in health care use that is associated  with obesity. Confounding means an apparent connection—such as the link between  increased health care costs and obesity—is influenced or even caused by a third factor. In this study, the authors tested if depression confounds the increase in health care seen in obese patients.

The study used telephone interviews to determine obesity and depression, and Group Health’s extensive medical records to calculate health care costs for 4,462 women aged 40–65. All were enrolled in Group Health Cooperative, a nonprofit health care system in Washington and northern Idaho. Obesity was measured as body mass  index (BMI), a standard obesity measure that is calculated from height and weight.  A BMI below 25 is considered normal weight, 25-30 considered overweight, and over 30 is considered obese. Depression was measured with a 9-item American  Psychiatric Association questionnaire.

The researchers found:

  • In middle-aged women, health care costs increased  with obesity. Specifically, costs increased 65 percent in women with a BMI of 30-35, and 157 percent in women with a BMI higher than 35, compared to women of  normal weight.
  • The trend was similar for all types of health care that the researchers examined: primary care, outpatient prescriptions, specialist  visits, inpatient care, and mental health care.
  • Health care costs increased with higher depression scores, but depression was a not a major confounder of the obesity results.
  • Even accounting for depression, health costs increased with every rise in BMI category.

The study concluded that in this population of women, obesity is associated with higher health care costs, but not because of co-occurring depression. Similarly, depression is associated  with higher costs, but not because of co-occurring obesity. These higher costs have an economic impact. Increased costs associated with depression were  spread across all types of health care, not just mental health care.

“Obesity and depression are  both very common,” Dr. Simon said, “so the increased costs we find  add up to a very large amount in the general population.” The  relationships among obesity, depression, and chronic illness related to obesity are complex, as are the effects of depression on behavior and health. But one thing is clear, the study’s authors said: Effective obesity prevention is a crucial factor in tackling our rising health care costs.

The National Institute of Mental  Health funded the work.

Dr. Simon’s co-authors were David  Arterburn, MD, MPH, Evette  J. Ludman, PhD, and Belinda H. Operskalski, MPH, of Group Health Research  Institute; Paul Rohde, PhD, of Oregon Research Institute, in Eugene, OR; and  Jennifer A. Linde, PhD, and Robert W. Jeffery, PhD, of the Division of  Epidemiology and Community Health at the University of Minnesota School of  Public Health, in Minneapolis. 

Journal of General Internal Medicine

Journal of  General Internal Medicine is the official journal of the Society of General Internal Medicine. It promotes improved patient care, research, and education in primary care, general  internal medicine, and hospital medicine. Its articles focus on topics such as  clinical medicine, epidemiology, prevention, health care delivery, curriculum development, and numerous other non-traditional themes, in addition to classic clinical research on problems in internal medicine.

About Kaiser Permanente

Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America’s leading health care providers and not-for-profit health plans. Founded in 1945, Kaiser Permanente has a mission to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve more than 12.4 million members in eight states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal Permanente Medical Group physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health. For more information, go to: kp.org/share.

David E. Arterburn, MD, MPH

Senior Investigator
Kaiser Permanente Washington Health Research Institute


Media contact

For more on Kaiser Permanente Washington Health Research Institute news, please contact:

Amelia Apfel


(425) 507-5455
After-hours media line: (206) 287-2055

page-twitter-icon.png @KPWaResearch