Health and economic burden of obesity


As the prevalence of overweight and obesity continues to climb, the challenges of quantifying the impact of this epidemic to inform public policies and health services becomes more pressing. The consequences of obesity on population health are far-reaching—as demonstrated in extensive analyses of health and economic consequences. For example, Calle and colleagues reported data from over 900,000 men and women in the American Cancer Society Cancer Prevention Study II showing excess mortality from cancer among obese men and women 1. Stewart and colleagues project the effects of obesity on life expectancy in the US and note that the adverse effect of obesity will outweigh any gains from smoking cessation 2. Fontaine and colleagues estimate that obesity substantially lessens life expectancy for US adult. For those age 20 expectancy can be reduced by up to 17% 3. In sum, excess mortality observed with increasing levels of obesity can be summarized in a number of ways to guide polices and practices that may prevent weight gain in adult years and reduce the burden of obesity.

Who Bears the Economic Costs of Obesity?
Most of the early cost estimates took a societal perspective; nonetheless, partitioning the total burden of obesity to different sectors that share the costs provides incentives to address the distribution issue and adopt preventive strategies. In particular recent work by Finkelstein and colleagues shows just how much of the burden is carried through to payers who support medicare where obese individuals have higher costs than normal weight individuals 4. 

Costs for employers have been reported by Finkelstein et al. 5 and by Thompson et al.6. Finkelstein et al. used data from two national samples of full-time employed adults 5. They estimated that overweight- and obesity-attributable costs ranged from $175 to $2485 dollars per year depending on the degree of overweight and gender, approximately 30% of these costs result from increased absenteeism. Although those with Class-III obesity represent only 3% of the employed population, they account for 21% of the costs. Another important work by Finkelstein et al. quantifies the costs to tax payers. They found that, in 1998, total medical bill due to overweight and obesity might have been as high as $78.5 billion in the United States. Medicare and Medicaid finance approximately half of these costs, private insurance pays 30%-40%, and roughly, 15% paid out of pocket7. The increase in the medical conditions (such as hypertension and hyperlipidemia) treated among obese individuals has been suggested to be a key determinant of increased spending from private health insurance 8.

Using the 2006 medical expenditure panel survey, Finkelstein and colleagues show that the annual cost of obesity among full time employed individuals is $73.1 billion. 61% of these costs are incurred by those over a BMI of 35 kg.m2, who represent just 37% of the obese population 9.

The evidence is overwhelming that excess weight is associated with increased morbidity and mortality. Current estimates of economic expenses related to excess weight clearly underestimate the true costs to society. To date, the majority of these estimates have evaluated only a narrow range of overweight- and obesity-related illness; they have not included factors, such as the impact of reduced physical functioning 10-12; and many have not accounted for the effects on those who are overweight but not obese. With the rising prevalence of overweight and obesity, we will continue to see growing effects and mounting costs on the individual, our communities, and our society as a whole. Finkelstein argues that obesity results from market forces, technologic advances that lower the cots of behaviors that promote obesity (inactivity at work, TV viewing, etc), and that obesity prevention efforts therefore must make it easier and cheaper to follow a healthy diet and engage in regular physical activity 13. 

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Literature cited
 

2.         Stewart ST, Cutler DM, Rosen AB. Forecasting the effects of obesity and smoking on U.S. life expectancy. N Engl J Med. Dec 3 2009;361(23):2252-2260.
3.         Fontaine KR, Redden DT, Wang C, Westfall AO, Allison DB. Years of life lost due to obesity. JAMA. Jan 8 2003;289(2):187-193.
4.         Finkelstein EA, Trogdon JG, Brown DS, Allaire BT, Dellea PS, Kamal-Bahl SJ. The lifetime medical cost burden of overweight and obesity: implications for obesity prevention. Obesity (Silver Spring). Aug 2008;16(8):1843-1848.
5.         Finkelstein E, Fiebelkorn C, Wang G. The costs of obesity among full-time employees. Am J Health Promot. Sep-Oct 2005;20(1):45-51.
6.         Thompson D, Edelsberg J, Kinsey K, Oster G. Estimated economic costs of obesity to U.S. business. Am J Health Promot. 1998;13:120-127.
7.         Finkelstein EA, Fiebelkorn IC, Wang G. National medical spending attributable to overweight and obesity: how much, and who's paying? Health Aff (Millwood). Jan-Jun 2003;Suppl Web Exclusives:W3-219-226.
8.         Thorpe KE, Florence CS, Howard DH, Joski P. The impact of obesity on rising medical spending. Health Aff (Millwood). Jul-Dec 2004;Suppl Web Exclusives:W4-480-486.
9.         Finkelstein EA, DiBonaventura M, Burgess SM, Hale BC. The costs of obesity in the workplace. J Occup Environ Med. Oct 2010;52(10):971-976.
10.         Coakley E, Kawachi I, Manson J, Speizer F, Willett W, Colditz G. Lower levels of physical functioning are associated with higher body weight among middle-aged and older women. Int J Obesity. 1998;22:958-996.
11.         Fine J, Colditz G, Coakley E, et al. A prospective study of weight change and health-related quality of life in women. JAMA. 1999;282:2136-2142.
12.         Fontaine K, Cheskin L, Barofsky I. Health-related quality of life in obese persons seeking treatment. J Fam Pract. 1996;43:265-270.
13.         Finkelstein EA, Strombotne KL. The economics of obesity. Am J Clin Nutr. May 2010;91(5):1520S-1524S.


Vitamin D and cancer - update


Much scientific and public health interest focuses on the potential for vitamin D to reduce risk of cancer and mortality from cancer (see typical media coverage weighing up the evidence). A number of new reports shed light on the potential for vitamin D to reduce risk of specific cancers and evaluate the trade off of risks and benefits.

Colon cancer
Perhaps the strongest evidence relates to colon cancer. Substantial evidence supports a link between vitamin D and reduced incidence of colon cancer – the third most common cancer among both men and women in the United States.  Studies show that people with higher circulating vitamin D levels can have as little as half the risk of developing colon cancer as those with lower vitamin D levels (International Agency for Research on Cancer 2008). This and other possible benefits were reviewed systematically by the International Agency for Research on Cancer (IARC) (International Agency for Research on Cancer 2008), and led to the recommendation that better understanding of possible adverse health effects of population supplementation, and the possible variation in benefits depending on the baseline serum 25-hydroxyvitamin D level, are necessary before recommending routine vitamin D supplementation for cancer prevention.

New evidence fills some of this research gap. In a follow-up of the National Health and Nutrition Examination Study III, Freedman and colleagues (Freedman, Looker et al. 2010) report no overall association of blood vitamin D levels and cancer mortality during 18 years. In this study, with only 884 total cancer deaths, the overall evidence did not support protection against death from cancer. However 28.5% of the deaths were due to lung cancer and the time course for vitamin D levels to protect against this disease may not have fallen in the 18-year interval. Colon cancer, the cancer site with the strongest evidence for a protective effect of vitamin D, did show a suggested inverse relation with higher baseline vitamin D levels having lower risk of colon cancer mortality. In a more detailed analysis of the colon cancer deaths in this cohort, Fiscella and colleagues (Fiscella, Winters et al. 2010) report that excess colon cancer deaths among African Americans followed national trends. Importantly in addition to race, not having health insurance, also predicted colon cancer mortality. Low blood vitamin D levels predicted mortality from colon cancer and accounted for some, but not all, the excess risk among African Americans. 

Non-Hodgkin Lymphoma
A large study combined data from 10 cohorts to relate vitamin D blood levels and risk of developing Non-Hodgkin Lymphoma (Purdue, Freedman et al. 2010). With 1353 new cases of lymphoma this study was well suited to evaluate the overall effect and also to look at the association in different age groups and subtypes of lymphoma. There was no clear trend for vitamin D levels and risk of lymphoma overall, or in men or women when they were examined separately. This large study rules out any important protective effect of vitamin D and lymphoma risk.

Breast cancer
Epidemiologic evidence on dietary intake and also studies of blood vitamin D levels and risk of disease are inconclusive (World Cancer Research Fund 2007). Only two studies have evaluated blood levels of vitamin D at diagnosis and survival after breast cancer. The first, published last year included 512 cases of breast cancer followed for an average of 11.6 years (Goodwin, Ennis et al. 2009). 116 women developed distant recurrence and 106 died during follow-up. This study showed an increase in risk of distant recurrence and death among those with low vitamin D levels.  New data from the WHEL study of over 3,000 women with breast cancer identified 518 women with new breast cancer events during an average of 7.3 years of follow-up (Jacobs, Thomson et al. 2010). In this substantially larger study, there was no evidence for a trend in risk with level of vitamin D overall, or when pre and postmenopausal women were evaluated separately. Despite these two studies the overall level of evidence remains inconclusive with limited events to inform these analyses.

Risks and benefits
The broader evaluation of risk and benefit of vitamin D supplementation have been summarized by Bischoff-Ferrari and colleagues (Bischoff-Ferrari, Shao et al., 2010). They draw on data from 12 randomized controlled trials of vitamin D supplementation and risk of fractures which show conclusive evidence of a dose response relation between higher-does (and higher achieved blood levels of vitamin D) and significantly reduced falls and fractures. They also consider cardiovascular disease and colon cancer risk as well as possible adverse effects on serum calcium. This analysis suggests that optimal health benefits are achieved with blood vitamin D levels of 75 to 110 nmol/l., which are achieved with oral doses of 1,800 to 4,000 IU of vitamin D per day. Current intakes in adults are insufficient to bring individuals up to the protective levels of vitamin D. Further work is needed to understand how optimal blood levels can be achieved in the majority of the US population.

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Literature cited



Evidence Review Shows Metformin Lowers Cancer Risk by 30 Percent

In an earlier post on CNiC, we summarized a few studies relating Metformin use to lower risk of cancer (previous post). We have also summarized the enormous range of evidence that overweight and obesity increase risk of cancer (review paper (pdf)).

Now a systemic review of the published literature in the journal Cancer Prevention Research gives strong evidence for consistent findings across studies that metformin reduces risk of cancer onset (incidence) and mortality (study).

What is a systematic review and meta-analysis?
The synthesis of research findings has long been a central part of a research review. It offers the potential to identify areas of agreement in a field and those where the science has discrepancies or require further research (Mosteller and Colditz 1996). Quantitative methods now allow for a number of summary estimates to evaluate the overall benefit (or harm) of a therapy or lifestyle intervention; the level of variation in results between studies; and with regression approaches, one can identify factors that contribute to the variation between studies (Colditz, Berkey et al. 1995). If quality is assessed one can also project how large a benefit (or harm) would be seen if an ideal or prefect study was implemented (Berlin and Colditz 1990). Given the variation in results between studies, we can also project the range of gains or improvements that could be reasonably seen should a program be implemented in a new setting with a defined set of characteristics that were addressed in the earlier collection of research studies.

New evidence?
The systematic review reported in Cancer Prevention Research by DeCensi and colleagues began by searching the medical literature and identifying some 464 publications that addressed metformin and cancer. They applied strict criteria for inclusion in the analysis and extracted results from 11 independent studies that they then analyzed. The studies included a total of 4,042 cases of cancer and 529 deaths. Combining the results from these studies they note that both cancer incidence and cancer mortality are reduced by 30% among users of metformin. These significant benefits overall were also evaluated for subtype of cancer (pancreas, liver, breast, colon, etc). Significant reduction in pancreatic and liver cancer was noted and similar reduction in breast and colon were observed, though the reduction was not statistically significant.

While results showed some variation among studies, the consistent 30 percent reduction in incidence is promising and justifies ongoing efforts to evaluate metformin in randomized controlled trials that will more directly evaluate the potential for metformin to reduce recurrence of breast cancer among 3582 women with stage I and II disease. Details of this trial are reported on the NIH clinical trials web site (link).

ENERGY trial
In an ongoing randomized clinical trial, we are evaluating weight loss interventions to improve quality of life and reduce risk of recurrence on women with early stage breast cancer (see summary). Just as weight loss sustained over 24 months reduced the risk of progression to diabetes, we will evaluate whether a similar approach can sustain weight loss, improve quality of life, and reduce recurrence of breast cancer.

Other approaches to weight loss in low-income populations also show promise. We have used web tools and telephone based technology to help sustain changes in diet and physical activity among inner city residents in Boston (Greaney, Quintiliani et al. 2009). Results of clinical trials will inform strategies to bring interventions to broader clinical populations, such as through networks of community health centers (see summary).

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Related Links

Literature Cited
Berlin, J. and G. Colditz (1990). "A meta-analysis of physical activity in the prevention of coronary heart disease." Am J Epidemiol 132: 612-628.

Colditz, G. A., C. S. Berkey, et al. (1995). "The efficacy of bacillus Calmette-Guerin vaccination of newborns and infants in the prevention of tuberculosis: meta-analyses of the published literature." Pediatrics 96(1 Pt 1): 29-35.

Greaney, M. L., L. Quintiliani, et al. (2009). "Weight management among patients at community health centers: the Be Fit Be Well study." Obesity Weight Manageement(October): 218-224.

Mosteller, F. and G. Colditz (1996). "Understanding Research Synthesis (meta-analysis)." Ann Rev Public Health 17: 1-32.