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Research on Obesity and Overweight:

AHRQ-Supported Research and Recent Findings

Program Brief

AHRQ-Supported Research Projects

Effect on Health and Health Care

Projecting consequences of better health for older adults.

The goal of this completed project was to augment an existing risk-factor model to make it suitable for examining the impact of important public health programs and goals on middle-aged and older adults (ages 45-74). The augmented model will be capable of exploring the consequences over time of changes in such risk factors as smoking, obesity, high blood pressure, and chronic disease on mortality, hospitalization, and nursing home admission.

Louise Russell, PI; Rutgers State University, New Brunswick, NJ. AHRQ grant HS11477, project period 6/1/01-1/31/03.

Disparities in care: Obesity and cancer screening.

For this completed study, researchers used national data collected as part of the 1998 National Health Interview Survey and AHRQ's 1996 Medical Expenditure Panel Survey (MEPS). The goals were to:

  1. Compare the rates of screening for colon, prostate, breast, and cervical cancer between people with and without obesity.
  2. Examine whether differences in cancer screening rates associated with obesity vary by sex or race.
  3. Examine whether differences in screening rates could be explained entirely by the higher illness burden experienced by people with obesity.

Christina Wee, PI; Beth Israel Deaconess Medical Center, Boston, MA. AHRQ grant HS11683, project period 9/30/01-9/29/03.

Obesity, weight loss, and access to preventive care.

The broad objectives of this completed research project were to assess whether intentional weight loss reduces mortality and to examine whether obesity acts as a barrier to preventive health care. Using data from the National Health Interview Survey, the researchers focused on the odds of receiving certain forms of preventive care such as Pap smears, mammography, and cholesterol testing, as well as identification of health risks by a health provider. The goals were to improve clinicians' ability to assess any long-term benefit from intentional weight loss and help them identify obese individuals as an at-risk population with respect to preventive health care.

Christina Wee, PI; Beth Israel Deaconess Medical Center, Boston, MA. AHRQ grant F32 HS00137, project period 11/1/99-10/31/00.

Recent Findings

Obesity contributes to significantly lower quality of life.

Researchers from the Mercer University School of Medicine examined the relationship between obesity and health-related quality of life in people aged 18 and older using data from the 2000 MEPS. After adjusting for socioeconomic factors and disease status, they found that quality of life decreased with increasing levels of obesity. Individuals who were obese had significantly lower health-related quality of life than those who were normal weight. These lower scores were seen even for obese people who did not have chronic diseases known to be linked to obesity.

Jia, Lubetkin, J Public Health 2005;27(2):156-64 (AHRQ grant HS13770).

Obesity is associated with decreased health status and a higher incidence of depression.

For this study, researchers randomly assigned 509 new adult patients to primary care physicians at a university medical center and monitored their use of services and related charges over 12 months. They found that obese patients were more likely to be women than men, were older, had poorer health status, and had a higher incidence of depression. Obese patients had a significantly higher number of visits to both primary care and specialty clinics and used more diagnostic services than non-obese patients. Obese patients also had significantly higher charges for primary care, specialty clinic, emergency services, hospitalization, and diagnostic services, as well as higher total charges.

Bertakis, Azari, Obes Res 2005;13(2):372-9 (AHRQ grant HS06167).

Researchers find that obesity impacts the medical visit.

The goal of this study was to investigate the influence of patient obesity on primary care physician practice style. This randomized, prospective study involved 509 patients assigned for care by 105 primary care resident physicians. The researchers collected sociodemographic information and data on health status, evaluation for depression, and satisfaction. Height and weight were measured to calculate the patients' BMI.

Analysis of visit videotapes revealed that obesity was not significantly associated with the length of the visit, but it influenced what happened during the visit. Physicians spent less time educating obese patients about their health and more time discussing exercise. Obesity was not related to discussions of nutrition. Physicians spent a greater portion of the visit on technical tasks when the patient was obese. Although pre-visit satisfaction was significantly lower for obese patients, there was no difference between obese and non-obese patients in post-visit satisfaction.

Bertakis, Azari, Obes Res 2005;13(9):1613-23 (AHRQ grant HS06167).

Obese white women are less likely than other women to undergo mammography to screen for breast cancer.

According to this study, obese white women are less likely than non-obese white women to undergo breast cancer screening, a relationship not seen in black women. Using data from the National Health Interview Survey, the researchers examined the relationship between body mass index and receipt of breast cancer screening in the preceding 2 years among women aged 50 to 75. Among the 5,277 eligible women, 72 percent reported mammography use (74 percent for white women and 70 percent for black women).

Higher BMI was associated with lower screening among white women. Mammography use was lowest in women with a BMI greater than 35. Moderately obese white women (BMI 35 to 40) were 17 percent less likely to have had a mammogram than normal weight white women. Adjusting for socioeconomic status and illness burden did not change the findings. The researchers suggest that negative body image and provider bias may account in part for these findings.

Wee, McCarthy, Davis, Phillips, J Gen Intern Med 2004;19:324-31 (AHRQ grant HS11683).

More prevalent severe obesity may explain black/white disparity in stage at breast cancer diagnosis.

Black women are typically diagnosed with breast cancer at a later stage than white women, putting them at greater risk of dying from the disease. According to this study, higher rates of morbid obesity among black women compared with white women may be a major factor in this disparity. In this study, black women were twice as likely as white women to be overweight and six times as likely to be morbidly obese. Also, black women were twice as likely to be diagnosed when the tumor was larger or had spread to nearby lymph nodes.

Overall, morbid obesity accounted for about one-third of the racial difference in stage of breast cancer diagnosis, even after accounting for other factors such as age, socioeconomic status, history of breast cancer screening, lifestyle, and reproductive history. This study involved 145 black women and 177 white women diagnosed with new cases of breast cancer in Connecticut in the late 1980s.

Jones, Kasl, McCrea, Curnen, et al., Am J Epidemiol 1997;146(5):394-404 (AHRQ grant HS06910).

Mammography found to be less accurate for obese women.

Overweight women have a 14 percent increased risk and obese women more than a 20 percent increased risk of having a false-positive mammogram. False-positive mammography results lead to increased anxiety for women and unnecessary health care costs for additional testing to evaluate the false-positive results. In this study, overweight women were 17 percent more likely to be recalled for further testing, while mildly obese women (BMI of 30-34) were 27 percent more likely to be recalled, and severely obese women (BMI of 35 or more) were 32 percent more likely to be recalled.

Elmore, Carney, Abraham, et al., Arch Intern Med 2004;164:1140-7 (AHRQ grant HS10591).

Obesity may be a barrier to cancer screening.

This study found an inverse relationship between body weight and cervical and breast cancer screening, suggesting that obesity may be an unrecognized barrier to preventive care. The researchers analyzed survey responses of 11,435 women who responded in the year 2000 to the National Health Interview Survey.

Researchers found that among women aged 18 to 75 who had not had a hysterectomy, 78 percent of overweight and obese women reported having a Pap smear in the preceding 3 years, compared with 84 percent of normal weight women. In women aged 50 to 75, fewer overweight (64 percent) and obese (62 percent) women had received a mammogram in the preceding 2 years, compared with normal weight women (68 percent). Heavier women were usually older, were less likely to be white or to have private health insurance, had lower socioeconomic status, and suffered a greater burden of illness. Yet there was still a 3 to 5 percent difference in screening rates after adjustment for these and other known barriers to care.

Wee, McCarthy, Davis, Phillips, Ann Intern Med 2000;132(9):697-704 (AHRQ grant F32 HS00137).

Morbidly obese women are more likely than others to develop colorectal cancer and die from it, but are less likely to be screened.

Colorectal cancer is the second leading cause of cancer death in the United States, and screening is the key to early diagnosis and treatment. In this study of almost 53,000 people aged 51 to 80, morbidly obese women (BMI of 35 or more) were nearly 6 percent less likely to be screened than normal weight women. The researchers examined self-reported colorectal cancer screening with fecal occult blood testing (FOBT) within the previous year or endoscopic screening (sigmoidoscopy or colonoscopy) with the previous 5 years. The overall colorectal cancer screening rate was 43.8 percent.

Rosen, Schneider, J Gen Intern Med 2004;19:332-8 (AHRQ grant T32 HS00020).

Being overweight or underweight does not preclude elective noncardiac surgery for most patients.

Relatively healthy overweight and underweight patients are not at any higher risk than normal weight patients for complications or longer hospital stays following many types of elective, noncardiac surgery. However, overweight people who undergo elective abdominal or gynecologic surgery have double the wound infection rates of normal weight patients, according to this study. Also, the most underweight and overweight patients have higher costs, perhaps indicating that more resources are expended on these patients to prevent complications. For this study, the researchers correlated the BMI of nearly 3,000 patients aged 50 and older undergoing elective noncardiac surgery with complications, length of hospital stay, and costs.

Thomas, Goldman, Mangione, et al., Am J Med 1997;102:277-83 (AHRQ grant HS06573).

Obese older adults tend to have lower quality of life than normal or overweight individuals.

The researchers evaluated the relationship between BMI and health-related quality of life scores among 1,326 adults with a mean age of 72 years. The goal was to estimate quality-adjusted life years lost to overweight, obesity, and associated conditions. Participants were divided into four groups: underweight, normal weight, overweight, and obese.

After controlling for age, sex, smoking history, and exercise, the normal BMI group had the highest score on the Quality of Well Being scale. The score for the obese group was much lower, suggesting a substantially lower quality of life. The researchers concluded that nearly 3 million quality years are lost in this country each year from obesity and associated conditions.

Groessl, Kaplan, Barrett-Connor, Ganiats, Am J Prev Med 2004;26(2):126-9 (AHRQ grant HS09170).

Regular exercise can reduce the risk of health decline among middle-aged adults.

Maintaining ideal body weight is important in preventing decline in overall health and physical functioning. But this study found that regular exercise can reduce the risk of health decline even among those who cannot achieve ideal weight. The researchers used 1992, 1994, and 1996 data to examine the relationship among BMI, exercise, overall health, and physical functioning in 7,867 adults who were aged 51 to 61 during the study period.

Overweight and obese individuals had a 29 percent and 36 percent, respectively, higher risk of health decline. They also had a 27 percent and 45 percent, respectively, higher risk of developing a new physical difficulty (e.g., being unable to climb a flight of steps without resting). However, regular exercise significantly reduced the risk of health decline and development of a new physical difficulty, even among obese individuals. For example, the risk of developing a new physical difficulty was 17 percent lower for those who performed vigorous activities less than once per month to as much as 43 percent lower for those who performed vigorous activities three or more times per week.

He, Baker, Am J Public Health 2004;94(9):1567-73 (AHRQ grant HS10283).

Researchers examine the associations between psychological eating behavior variables and body weight and size.

This study involved 1,470 women aged 45-68 enrolled in the Whitehall II study of English civil servants. The researchers examined the association between restraint, hunger, and disinhibition and body weight and size. Five measures of body size were examined: BMI, weight in kilograms, waist measurement, hip measurement, and waist-hip ratio.

The researchers found that disinhibition and hunger scores were strongly and directly associated with all measures of body weight and size. High disinhibition coupled with low levels of restraint was associated with the greatest weight and size. The authors concluded that these may be useful concepts for future research on the socioeconomic gradient in obesity and overweight.

Dykes, Brunner, Martikainen, Wardle, Int J Obes Relat Metab Disord 2004;28(2):262-8 (AHRQ grant HS06516).

Obesity is one of several factors affecting need for inpatient rehabilitation.

Individuals who undergo total hip replacement usually gain substantial pain relief and improved functioning. Those who are older, obese, living alone, or unable to walk at discharge are more likely to be discharged to a rehabilitation facility than directly home, according to this study. The researchers analyzed data on 1,276 patients aged 65 to 94 who had hip replacement surgery in 1995. More than half of the patients were discharged from the hospital to a rehabilitation facility. After adjusting for other factors, those who were obese were 29 percent more likely to be discharged to a rehabilitation facility.

Pablo, Losina, Phillips, et al., Arthritis Rheum 2004;51(6):1009-17 (AHRQ grant HS09775).

Obesity contributes to early-onset heart problems.

Although obese adults undergo coronary angioplasty and other techniques to relieve coronary narrowing at a younger age than people who are not obese, weight does not appear to affect their recovery from these procedures. The researchers classified 1,631 patients who underwent percutaneous coronary intervention (PCI) as underweight, normal weight, overweight, or obese. They further examined patients' need 12 months later for repeat procedure, survival, quality of life, and health status.

Researchers found that obese patients were significantly younger than other patients at the time of PCI. However, overweight and obese patients appeared to benefit just as much from PCI as normal-weight patients, while underweight patients had poorer outcomes than patients in other weight groups.

Poston, Haddock, Conard, Spertus, Int J Obes 2004;28:1011-7 (AHRQ grant HS11282).

Obese individuals stay in the hospital longer than normal-weight individuals.

These researchers used survey data to estimate hospital stay differences over four 5-year periods among patients in five groups (underweight, normal weight, overweight, obese, and morbidly obese).

Overweight and obese individuals had longer hospital stays than normal-weight individuals, although the association between BMI and length of stay varied over the four time periods. During the 1971-1975 period, for example, their stays were 25 percent (overweight), 45 percent (obese), and 54 percent (morbidly obese) longer. For the period 1976-1980, their stays were 60 percent, 94 percent, and 218 percent longer, respectively. With the exception of one followup period, underweight individuals had longer hospital stays than normal-weight individuals, probably due to illness-induced weight loss.

Zizza, Herring, Stevens, Popkin, Am J Public Health 2004;94:1587-91. See also: Zizza, Herring, Stevens, Carey, Obes Res 2003;11(12):1519-25 (AHRQ grant T32 HS00032).

Obesity appears to be more prevalent in adults with sensory, physical, and mental health conditions.

One-quarter of adults with disabilities are obese, compared with 15 percent of those without disabilities, according to this 1994-1995 survey of more than 145,000 community-dwelling adults. The highest risk for obesity was among people with lower extremity mobility difficulties.

In general, adults with disabilities were as likely as those without disabilities to attempt weight loss. However, adults with severe lower-extremity mobility difficulties were less likely to attempt weight loss, and those with mental illness were more likely to try to lose weight, compared with nondisabled adults. Exercise counseling by physicians was reported less often among adults with severe lower-extremity and upper-extremity mobility difficulties.

Weil, Wachterman, McCarthy, et al., JAMA 2002;288(10):1265-8 (AHRQ grant HS10223).

Lower educational attainment is associated with a higher BMI.

These researchers used data on 665 overweight or obese primary care patients participating in an ongoing obesity intervention to examine whether psychosocial and behavioral factors mediate the relationship between sociodemographic factors and BMI.

Researchers found that after controlling for decisional balance, social support, self-efficacy, energy intake, and energy expenditure, lower educational attainment was associated with a higher BMI. However, ethnicity was not associated with BMI after accounting for psychosocial and behavioral factors. They concluded that cross-sectional relationships between demographic, psychosocial, and behavioral variables and BMI are complex. They called for more research to devise better weight management strategies.

Baughman, Logue, Sutton, et al., Prev Med 2003;37:129-37. See also: Sutton, Logue, Jarjoura, et al., Obes Res 2003;11(5):641-52 (AHRQ grant HS08803).

Study finds little difference in patient satisfaction among obese compared with non-obese patients.

Patients with obesity experience psychosocial consequences because of their weight and sometimes report physician bias. These researchers examined whether obesity is associated with lower patient satisfaction with outpatient care. The study involved 2,858 patients seen at 11 academically affiliated primary care practices in Boston.

Compared with normal weight patients, overweight and obese patients reported lower overall satisfaction scores at their most recent visit. However, after adjustment for illness burden and other factors, the scores were still lower but were not statistically significant. Patient satisfaction with their usual provider and practice did not vary by BMI group. The researchers concluded that obesity is associated with only modest decreases in satisfaction scores, which are explained largely by a higher illness burden among obese patients.

Wee, Phillips, Cook, et al., J Gen Intern Med 2002;17(2):155-9 (AHRQ grant F32 HS00137).

Study finds obesity is linked with area of residence, resources, land use, and other environmental factors.

The built environment includes urban design factors, land use, and availability of public transportation, as well as the available activity options for people within that space. These researchers reviewed published research on the influence of the built environment on obesity.

Although the studies varied in their methods and levels of assessment (individual, county, etc.), they did show that obesity is linked with area of residence, resources, television, terrain and suitability for walking, land use, sprawl, and level of deprivation. The built environment can both facilitate and hinder physical activity and healthful eating. For example, poorer neighborhoods have three times fewer supermarkets than wealthier neighborhoods but contain more fast-food restaurants and convenience stores.

Also, areas with safety concerns, few recreational facilities, uneven and hilly terrain, and/or insufficient lighting can hinder physical activity. In contrast, residents in neighborhoods with more available physical activity resources, including sidewalks and safe streets, report higher activity levels.

Booth, Pinkston, Walker, Poston, J Am Diet Assoc 2005;105(5 Suppl 1):S110-7 (AHRQ grant HS11282).

One-third of people misidentify themselves as overweight, underweight, or normal weight.

In this study, researchers analyzed how adults classified their weight in a 1991 survey. They found that about 28 percent of overweight people judged their weight to be "just about right," while 24 percent of people who thought they were overweight were in fact normal weight or underweight, according to their BMI. Overall, 17 percent of people underassessed their weight category, and 12 percent overassessed their weight category, based on BMI.

Men were more likely than women to fail to recognize that they were overweight; 40 percent of overweight men considered their weight to be "just about right" compared with 15 percent of overweight women. On the other hand, 29 percent of normal-weight women thought they were overweight compared with 8 percent of normal weight men. Adults who were white, younger, more educated, or more affluent were more likely than others to consider themselves heavier than their actual BMI.

Chang, Christakis, J Gen Int Med 2001;16:538-43 (AHRQ grant T32 HS00084).

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Health Care Costs

Recent Findings

Hospital costs associated with weight-loss surgery increased six-fold between 1998 and 2002.

The number of Americans having weight-loss surgery more than quadrupled between 1998 and 2002—from 13,386 to 71,733—with part of the increase resulting from a 900 percent rise in operations on patients between ages 55 and 64, according to this study. During the same period, hospital costs for weight-loss surgery increased from $157 million a year to $948 million, and the average cost per surgery increased by about 13 percent, from $11,705 to $13,215.

To be considered medically eligible for weight-loss surgery (bariatric surgery), a patient must have a BMI greater than 40 (or greater than 35 with serious obesity related complications such as diabetes or obstructive sleep apnea). Approximately 395,000 Americans aged 65 to 69 were medically eligible for this surgery in 2005. This number could increase by approximately 20 percent to 475,000 by 2010. If this happens, it will have important cost implications for the Medicare program, according to the authors of the study.

Encinosa, Bernard, Steiner, Chen, Health Aff 2005;24(4):1039-46 (Intramural). Reprints (AHRQ Publication No. 05-R059) are available from AHRQ.*

Total health care expenditures are higher for obese individuals compared with those who are overweight or normal weight.

Researchers examined data from AHRQ's MEPS on health care costs in 2002 for adults aged 55 and older. They found that obese individuals had higher total mean expenses for medical care compared with people in other weight groups. The mean total expense for obese individuals was $7,235, compared with $5,390 and $5,478 for normal weight and overweight individuals, respectively. The mean inpatient expense for obese individuals was $2,555, compared with $1,727 for normal weight individuals and $1,698 for overweight individuals.

Prescription medicine expenditures were also higher for obese people. The mean expense was $1,688 for obese people, $1,089 for normal weight people, $1,184 for overweight individuals, and $1,121 for those who were underweight.

For more information, go to http://meps.ahrq.gov/mepsweb/data_stats/Pub_ProdResults_Details.jsp?pt=Statistical%20Brief&opt=2&id=664 to access Statistical Brief No. 68 (Intramural).*

Study examines correlation between diabetes, obesity, and health expenditures.

Data from the Household Component of MEPS show that in 2000, more than $18 billion was spent on health care for people with diabetes. Research has consistently shown that the obesity epidemic is a major contributing factor in the increasing number of people who have diabetes and other health conditions. According to this study, adults with diabetes were more than three times as likely to be extremely obese and nearly twice as likely to be obese as adults without diabetes.

For more information, go to http://meps.ahrq.gov/mepsweb/data_stats/Pub_ProdResults_Details.jsp?pt=Statistical%20Brief&opt=2&id=587 to access Statistical Brief No. 34 (Intramural).*

Data show relationship between weight and health insurance status.

Researchers compared MEPS data from 1987 and 2001 to examine trends in weight and health insurance status. They found that for all categories of health insurance status, there was an increase in obesity during the time period studied. Adults with public-only health insurance were the most likely to be obese in 1987 (22.8 percent) and 2001 (31.1 percent), a 36 percent relative increase over the period. There was a relative increase in obesity of 84 percent for individuals with private insurance (from 12.8 percent to 23.6 percent) and a relative increase of 60 percent for the uninsured (from 13.9 percent to 22.2 percent).

For more information, go to http://meps.ahrq.gov/mepsweb/data_stats/Pub_ProdResults_Details.jsp?pt=Statistical%20Brief&opt=2&id=601 to access Statistical Brief No. 37 (Intramural).*

Gastric bypass can dramatically improve the health of severely obese individuals at a reasonable cost.

These researchers performed a cost-effectiveness analysis of gastric bypass versus no treatment for relatively healthy women and men aged 35 to 55 who had a BMI between 40 and 50. Conservative therapies—such as diet, exercise, behavior therapy, and medication—had been unsuccessful for these people.

Although there was a risk of postoperative death and complications, gastric bypass resulted in a mean 58 percent loss of excess weight (above a BMI of 22) 5 years later. In all risk subgroups, the cost-effectiveness ratios of gastric bypass versus no treatment were favorable, at less than $50,000 per quality-adjusted life year. The ratios ranged from about $5,000 to $16,000 for women and from about $10,000 to $35,600 for men, depending on age and initial BMI. Since the reduction in lifetime medical cost was no greater than the cost of treatment in any subgroup, gastric bypass was not cost-saving from the payer perspective.

This study did not include severely obese patients with chronic medical conditions for whom the surgical risks, as well as the benefits of weight loss, would be greater.

Craig, Tseng, Am J Med 2002;113:491-8 (AHRQ grant T32 HS00083).

Current as of April 2006
Internet Citation: Research on Obesity and Overweight: : AHRQ-Supported Research and Recent Findings. April 2006. Agency for Healthcare Research and Quality, Rockville, MD. http://archive.ahrq.gov/research/findings/factsheets/quality/obesity/obesity2.html