Effect of middle age obesity on old age survival

A recent study from the University of Manitoba found that while obesity was greatly increasing there, its immediate impact on poor health was not as strong as feared. The following table displays their results in a way that nicely demonstrates the relationship between several risk factors, and highlights that those in middle age (defined as 50) had the highest probability of being obese. While health differences were not as large as expected in cross section, some of the health impacts of obesity in middle age may be deferred to old age.

The impact of obesity in middle age has been shown to have an impact on mortality even among healthy survivors living to age 65 or over, providing evidence that some of the negative consequences of middle aged obesity identified in Manitoba may be deferred.

Several points.

  • Even among those surviving to age 65+, being obese at middle age shortens your remaining lifespan compared to those of normal weight.
  • The very high mortality of very low old age BMI (assessed at the 1994 National Long Term Care Survey interview, all persons were age 65+) is almost certainly due to pre-existing illness at the 1994 interview. Mortality was assessed from the 1994 survey until December 31, 1995.
  • The number of persons with very low age 50 BMI who survived to make it into this analysis (on average ~20 years later), is a small and unusual group, and could be error. BMI at age 50 was measured using recalled weight at age 50 at the 1994 NLTCS.
  • The primary take home is that higher BMI at age 50 increases mortality roughly 20 years later conditional upon surviving that long, net of other factors such as smoking, income and demographics, showing that middle age obesity has a measurable, deferred mortality impact even among healthy survivors. Further analyses excluding respondents who were likely sick at the 1994 NLTCS interview confirms the general story.

This is a bit more evidence that the risk factor profile of persons in middle age influences their old age health, and therefore the cost of their health care.

*******

Gail Marchessault. Obesity in Manitoba Adults. University of Manitoba, Centre for Health Policy. October 2011. Overview based on full report Adult Obesity in Manitoba, Prevalence, Associations and Outcomes by Randy Fransoo, Patricia Martens, Heather Pryor, et al. 2011.

Donald H. Taylor, Jr and Truls Østbye. The Effect of Middle- and Old-Age Body Mass Index on Short-Term Mortality in Older People. Journal of the American Geriatrics Society 2002;49(10):1319-26.

About Don Taylor
Professor of Public Policy at Duke University (with appointments in Business, Nursing, Community and Family Medicine, and the Duke Clinical Research Institute). I am one of the founding faculty of the Margolis Center for Health Policy, and currently serve as Chair of Duke's University Priorities Committee (UPC). My research focuses on improving care for persons who are dying, and I am co-PI of a CMMI award in Community Based Palliative Care. I teach both undergrads and grad students at Duke. On twitter @donaldhtaylorjr

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