Obesity may be associated with disability in workers

Apr 24 2007

Obese individuals appear more likely to file workers, compensation claims for injuries on the job, according to a report in the April 23 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.

A second report in the same issue suggests that older Americans with a body mass index (BMI) of between 25 and 30, considered to be overweight, may have a higher risk of disability but a lower risk of death than those with BMI in the recommended range of 18.5 to 25.

Obesity is an increasing public health problem and a risk factor for many chronic diseases and death, according to background information in the articles. Increased BMI, calculated as weight in kilograms divided by height in meters squared, has been shown to be associated with increased costs to employee health plans. Obese workers have up to 21 percent higher health care costs than those whose weight is in the recommended range. "Less is known about more direct costs of obesity to employers, such as work-related illness and injury," the authors write.

Truls 'stbye, M.D., Ph.D., and colleagues at Duke University Medical Center, Durham, N.C., studied 11,728 health care and university employees who completed at least one health risk assessment questionnaire, available yearly to all employees eligible for health benefits'between 1997 and 2004. The assessment included a measure of height and weight. Workers with a BMI of less than 18.5 were categorized as underweight; between 18.5 and 24.9, recommended weight; 25 to 29.9, overweight; 30 to 34.9, obesity class I; 35 to 39.9, obesity class II; and 40 or higher, obesity class III.

Over an average of three years of follow-up, workers with higher BMIs tended to have more workers' compensation claims'those in the group with the highest BMI (40 or greater) had twice the rate of claims as those at the recommended weight. "Because the number of lost workdays and the costs per claim also increase rapidly with BMI, the effects of BMI on lost workdays and costs were even stronger," the authors write. "The number of lost workdays was almost 13 times higher, medical claims costs were seven times higher and indemnity claims costs were 11 times higher among the heaviest employees compared with those of recommended weight."

This association between BMI and claims was apparent for injuries or illnesses involving most parts of the body, but was most pronounced in claims related to the back, wrist or arm, neck or shoulder, and knee, foot or hip. The types of injuries most strongly related to BMI were sprain or strain, contusion or bruise, and pain or inflammation.

"Maintaining healthy weight not only is important to workers but should also be a high priority for their employers given the strong effect of BMI on workers' injuries," the authors conclude. "Complementing general interventions to make all workplaces safer, work-based programs targeting healthy eating and physical activity should be developed and evaluated."

In the second study, Soham Al Snih, M.D., Ph.D., and colleagues at the University of Texas Medical Branch, Galveston, and colleagues studied 12,725 adults 65 years or older who were not disabled at the beginning of the study. At initial interviews, which occurred between 1982 and 1993, researchers gathered information about health conditions, demographic information and psychosocial characteristics. Blood pressure, height and weight, and physical function were also measured. Follow-up interviews, in person or by phone, were conducted annually for seven years.

Over the follow-up period, 3,570 participants became disabled, 2,019 died, and 5,681 were known to be alive and non-disabled. The average BMI was 26.4 for non-disabled individuals, 26.4 for disabled individuals and 25.7 for those who died. "Subjects with BMIs of lower than 18.5 [underweight] or 30 or higher [obese] at baseline were significantly more likely to experience disability during the follow-up period," the authors write. In contrast, those who had BMIs of 25 to 34.9, considered to be overweight, had a lower risk of death during the study compared with those whose BMIs were less than 25 or 35 or higher. "Disability-free life expectancy is greatest among subjects with a BMI of 25 to less than 30," they continue.

There are several possible explanations for the link between obesity and disability in the elderly, the authors note. "Obesity is associated with several conditions that, in turn, are risk factors for subsequent disability, including osteoarthritis of the weight-bearing joints, diabetes mellitus and cardiovascular disease," they write. There are also several potential reasons for the weak link between obesity and death. For instance, BMI may not be an accurate measure of obesity in older adults. In addition, because obesity and death are clearly linked in younger adults, it is possible that individuals at risk of early death because of high BMI die before they reach age 65.

In addition, "obesity might have a protective effect at older ages that is less important at younger ages. This protective effect might counterbalance the known adverse consequences of obesity on survival." For instance, obesity might reduce the risk of hip fractures, or allow individuals who get sick to survive with a low calorie intake for a longer period of time.

"Assessments of the effect of obesity on the health of older Americans should account for mortality and incidence of disability," the authors conclude.

Editorial: Further Research Needed to Illuminate Link Between Obesity, Disability

As evidence accumulates for an association between obesity and frailty, a dialogue must begin regarding the consequences of rising obesity rates for the aging population, write Luigi Ferrucci, M.D., Ph.D., National Institute on Aging, Baltimore, and Dawn Alley, Ph.D., University of Pennsylvania, Philadelphia, in an accompanying editorial.

"Several important questions about the relationship between obesity and disability remain unanswered," Drs. Ferrucci and Alley write. "How does obesity result in disability independent of disease, Are there ways to intervene in this process by making obesity less disabling, and are there ways to intervene without weight loss, which may be risky in older persons' Why is obesity closely related to disability in old age but less related to mortality, Does obesity exert a protective effect in elderly patients'"

"Given the costs, the difficulties, and the burden associated with treating obesity, there is an overwhelming need for research that addresses these questions," they conclude.

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