The mediating effect of leptin on the relationship between body weight and knee osteoarthritis in older adults.

OBJECTIVE: Obesity is associated with an increased risk of osteoarthritis (OA) of the knee. Emerging evidence suggests that adipokines, substances produced by adipose tissue, may play a role in the development of knee OA. The aim of this study was to determine whether the inflammatory adipokine leptin partially mediates the relationship between body mass index (BMI) and knee OA. METHODS: We used baseline data from 653 participants who were 70 years of age or older in the population-based Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly Boston Study. Height and weight were measured, and participants were assessed for knee OA using clinical criteria. Serum leptin was measured using a microsphere-based assay. RESULTS: The average BMI and the average serum leptin level were 27.5 kg/m(2) and 589 pM, respectively; the prevalence of knee OA was 24.7%. In regression models adjusted for covariates, we found that a 5-kg/m(2) increase in BMI was associated with 32% increased odds of knee OA (odds ratio [OR] 1.32, 95% confidence interval [95% CI] 1.10, 1.58); a 200-pM increase in serum leptin levels was associated with 11% increased odds of knee OA (OR 1.11, 95% CI 1.05, 1.17). The ratio of the standardized coefficients for the indirect:total effect calculated using the product-of-coefficients method was 0.49, suggesting that approximately half of the total effect of BMI on knee OA may be mediated by serum leptin. The estimated 95% CIs for the mediated effect suggest that this effect is statistically significant. Similarly, mediation analysis using a counterfactual approach suggested that the effect of leptin mediation was statistically significant. CONCLUSION: We found that almost half of the association between elevated BMI and knee OA could be explained by the inflammatory adipokine leptin.

The mediating effect of chronic pain on the relationship between obesity and physical function and disability in older adults.

OBJECTIVES: To determine the extent to which bodily pain mediates the effect of obesity on disability and physical function. DESIGN: Cross-sectional analysis. SETTING: Population-based sample of residents in the greater Boston area. PARTICIPANTS: Community-dwelling adults aged 70 and older (N=736). MEASUREMENTS: Body mass index (BMI), obtained from measured height and weight, was categorized as normal weight (19.0-24.9 kg/m2), overweight (25.0-29.9 kg/m2), or obese (≥30.0 kg/m2). Main outcome measures were the Physical Component Summary of the Medical Outcomes Study 12-item Short-Form Survey (PCS), activity of daily living (ADL) disability, and Short Physical Performance Battery (SPPB) score. Chronic pain was assessed according to the number of weight-bearing joint sites that had pain (hips, knees, feet and pain all over). RESULTS: Older obese adults had greater ADL disability and lower SPPB and PCS scores than their nonobese counterparts, although in sex-stratified adjusted analyses, obesity was adversely associated with outcomes only in women. Obesity was associated with greater number of pain sites; and more pain sites were associated with greater odds of disability. Mediation analysis suggests that pain is a significant mediator (22-44%) of the adverse effect of obesity on disability and physical function in women. CONCLUSION: Bodily pain may be an important treatable mediator of the adverse effect of obesity on disability and physical function in women.

The relationship between symptoms of depression and body weight in younger adults.

A bidirectional relationship between obesity and depression may exist, though previous results are conflicting. The objectives of our study were to determine whether there is a bidirectional relationship between obesity and symptoms of depression in younger adults and whether this relationship varies with sociodemographic factors. We used data from 7,980 participants in the National Longitudinal Survey of Youth 1979 to examine whether baseline depressive symptoms (score ≥ 10 on a seven-item subscale of the CES-D) in 1992, predicted adjusted percent change in BMI between 1992 and 1994. We then examined whether obesity in 1992 predicted the development of symptoms of depression in 1994, after adjustment for confounders. We found that the presence of baseline depressive symptoms was not prospectively associated with increase in percent BMI, except in Hispanic women. Additionally, baseline obesity was not associated with higher risk of future symptoms of depression in the sample overall (adjusted risk ratio (RR) 1.20; 99% CI 0.91-1.60). However, in those of higher socioeconomic status, obesity was associated with almost double the risk of depressive symptoms compared to nonobese (highest income category: adjusted RR 1.97; 99% CI 1.14-3.40). We concluded that although obesity was not associated with risk of depression symptoms in the population overall, obesity was associated with an increased risk of developing depressive symptoms in those of higher socioeconomic status. Sociodemographic factors may be important modifiers of the relationship between obesity and depression.

Obesity, race, and risk for death or functional decline among Medicare beneficiaries: a cohort study.

BACKGROUND: The adverse effect of obesity on health outcomes may be lower in older and African American adults than in the general U.S. population. OBJECTIVE: To examine and compare the relationship between obesity and all-cause mortality and functional decline among older U.S. adults. DESIGN: Longitudinal cohort study. SETTING: Secondary analysis of data from the 1994 to 2000 Medicare Current Beneficiary Surveys, linked to Medicare enrollment files through 22 April 2008. PARTICIPANTS: 20,975 community-dwelling participants in the 1994 to 2000 Medicare Current Beneficiary Surveys who were aged 65 years or older. MEASUREMENTS: All-cause mortality through 22 April 2008; new or worsening disability in performing activities of daily living (ADLs) and instrumental activities of daily living (IADLs) in 2 years. RESULTS: 37% of the study sample were overweight (body mass index [BMI] of 25 to <30 kg/m(2)), 18% were obese (BMI ≥30 kg/m(2)), 48% died during the 14-year follow-up, and 27% had ADL and 43% had IADL disability at baseline. Among those without severe disability at baseline, 17% developed new or worsening ADL disability and 26% developed new or worsening IADL disability within 2 years. After adjustment, adults with a BMI of 35 kg/m(2) or greater were the only group above the normal BMI range who had a higher risk for mortality (hazard ratio, 1.49 [95% CI, 1.20 to 1.85] in men and 1.21 [CI, 1.06 to 1.39] in women, compared with the reference group [BMI of 22.0 to 24.9 kg/m(2)]; P for BMI-sex interaction = 0.003). In contrast, both overweight and obesity were associated with new or progressive ADL and IADL disability in a dose-dependent manner, particularly for white men and women. Significant interactions were detected between BMI and sex but not between BMI and race for any outcome, although risk estimates for ADL disability seemed attenuated in African American relative to white respondents. LIMITATION: This was an observational study, baseline data were self-reported, and the study had limited power to detect differences between white and African American respondents. CONCLUSION: Among older U.S. adults, obesity was not associated with mortality, except for those with at least moderately severe obesity. However, lower levels of obesity were associated with new or worsening disability within 2 years. Efforts to prevent disability in older adults should target those who are overweight or obese. PRIMARY FUNDING SOURCE: National Institute of Diabetes and Digestive and Kidney Diseases.

Parity and the association with diabetes in older women.

OBJECTIVE: To examine the relationship of parity with diabetes and markers of glucose homeostasis in older women. RESEARCH DESIGN AND METHODS: We used data from the female participants in the Cardiovascular Health Study, a longitudinal cohort of adults aged >or=65 years. These data included an assessment of parity (baseline) and fasting serum levels of glucose, insulin, and medication use (baseline and follow-up). We estimated both the cross-sectional relationship of parity with baseline diabetes and the relationship of parity with incident diabetes. RESULTS: In unadjusted analyses, women with grand multiparity (>or=5 live births) had a higher prevalence of diabetes at baseline compared with those with fewer births and with nulliparous women (25 vs. 12 vs. 15%; P < 0.001). In regression models controlling for age and race, grand multiparity was associated with increased prevalence of diabetes (prevalence ratio 1.57 [95% CI 1.20-2.06]); with addition of demographic and clinical factors to the model, the association was attenuated (1.33 [1.00-1.77]). In final models that included body anthropometrics, the association was no longer significant (1.21 [0.86-1.49]). In those without diabetes at baseline, parity was not associated with incident diabetes or with fasting glucose; however, there was a modest association of parity with fasting insulin and homeostasis assessment model of insulin resistance. CONCLUSIONS: Grand multiparity is associated with diabetes in elderly women in cross-sectional analyses. This relationship seems to be confounded and/or mediated by variation in body weight and sociodemographic factors by parity status. In older nondiabetic women, higher parity does not pose an ongoing risk of developing diabetes.

Adolescent obesity and future college degree attainment.

The current impact of adolescent obesity on educational attainment is not clear. The objectives of our study were to determine whether adolescent obesity is associated with college degree attainment and how this association may have changed over time. We used data from a contemporary national cohort of over 4,000 persons who were adolescents (aged 14-18) in 1997 to assess the relationship between adolescent obesity and education. To assess for changes in this relationship over time, we also analyzed an older, similarly structured cohort of over 3,000 persons who were adolescents (aged 16-18) in 1981. Our primary outcome was college degree completion. We found that in the older cohort (adolescents in 1979), there were no differences in college degree attainment by adolescent weight status before and after adjustment. However, unadjusted analysis of the contemporary cohort (adolescents in 1997) demonstrated that those who were normal weight as adolescents had a higher prevalence of college degree attainment at follow-up compared to obese adolescents (24% vs. 10%). After adjustment for socio-demographic variables (age, sex, race, height, parental income-to-poverty ratio, parental education, aptitude test scores), obese adolescents were less likely to have attained a college degree compared to normal weight peers (adjusted risk ratio 0.61 95% confidence interval 0.38-0.83). Expectations for a future college degree did not vary by weight status and did not explain this observation. In conclusion, adolescent obesity is associated with lower likelihood of college completion. This relationship was not observed in an older cohort of adolescents.

Psychosocial stress and 13-year BMI change among blacks: the Pitt County Study.

Adverse psychosocial exposures may partially drive the high rates of obesity among blacks. The objective of this study was to prospectively examine the relationship between perceived psychosocial stress and percent change in BMI among adult black men and women. We used data from 756 women and 416 men who were participants in the Pitt County Study, a community-based, prospective cohort study of blacks in eastern North Carolina. Participants were aged 25-50 years of age on entry into the study in 1988 and follow-up was obtained in 2001. Using multivariable linear regression, we calculated the adjusted mean percentage change in BMI over the follow-up period for each tertile of baseline measures of the Perceived Stress Scale (low, medium, and high), adjusted for potential confounders. For black women, higher levels of psychosocial stress at baseline predicted higher adjusted percentage increase in BMI over the 13-year follow-up: low stress 12.0% (95% CI 9.6-14.4), medium stress 16.3% (95% CI 13.7-18.9), and high stress 15.5% (95% CI 13.1-17.8). For black men, perceived stress was not associated with percent BMI change. These data suggest that interventions targeting obesity in black women should consider the potential impact of emotional stress on weight change.

Risk of cardiovascular events and death--does insurance matter?

BACKGROUND: Many Americans lack health insurance. Despite good evidence that lack of insurance compromises access to care, few prospective studies examine its relationship to health outcomes. OBJECTIVE: To determine the relationship between insurance and cardiovascular outcomes and the relationship between insurance and selected process measures. DESIGN AND PARTICIPANTS: We used data from 15,792 participants in the Atherosclerosis Risk in Communities Study, a prospective cohort study. Participants were enrolled in 1987-1989 and returned for follow-up visits every 3 years, for a total of 4 visits. MAIN OUTCOME MEASURES: We estimated the hazard of myocardial infarction, stroke, and death associated with insurance status using Cox proportional hazard modeling. We used generalized estimating equations to examine the association between insurance status and risk of (1) reporting no routine physical examinations, (2) being unaware of a personal cardiovascular risk condition, and (3) inadequate control of cardiovascular risk conditions. RESULTS: Persons without insurance had higher rates of stroke (adjusted hazard ratio, 95% CI 1.22-2.22) and death (adjusted hazard ratio 1.26, 95% CI 1.03-1.53), but not myocardial infarction, than those who were insured. The uninsured were less likely to report routine physical examinations (adjusted risk ratio 1.13, 95% CI 1.08-1.18); more likely to be unaware of hypertension (adjusted risk ratio 1.12, 95% CI 1.00-1.25) and hyperlipidemia (adjusted risk ratio 1.11, 95% CI 1.03-1.19); and more likely to have poor blood pressure control (adjusted risk ratio 1.23, 95% CI 1.08-1.39). CONCLUSIONS: Lack of health insurance is associated with increased rates of stroke and death and with less awareness and control of cardiovascular risk conditions. Health insurance may improve cardiovascular risk factor awareness, control and outcomes.

Differences in access to outpatient medical care for black and white adults in the rural South.

OBJECTIVES: We compared black and white adults in the rural South on multiple indicators of access to outpatient medical care and assessed whether any differences might be explained by group differences in socioeconomic situations or proximity to medical resources. DESIGN: Cross-sectional telephone survey. SUBJECTS: Survey respondents were 1237 black and 2158 white adults from 113 rural counties in 6 southern states. MEASURES: Blacks and whites were compared on a variety of commonly used survey measures of access, some followed in the Healthy People 2010 Initiative. Access comparisons were adjusted for age, gender, and health status and then reassessed with adjustments for individual socioeconomic indicators and county medical resources: physician-to-population ratios, the presence of hospitals and federally qualified health centers, and urban adjacency. RESULTS: Compared with whites, blacks reported similar or higher use of outpatient services over the previous year, including the likelihood of having had an outpatient physician visit and regular checkup. Nevertheless, blacks more often reported forgoing needed care, encountering various barriers, and experiencing dissatisfaction with some aspects of care. Adjusting for socioeconomic factors generally reduced but did not eliminate black-white access differences, whereas adjusting for county medical care resources did not affect measured group differences. CONCLUSIONS: Blacks and whites in the rural South report similar use rates of outpatient medical care, but blacks more often report unmet needs, barriers to care, and dissatisfaction with care. Beyond socioeconomic differences, black versus white differences in sites of care, the quality of care received, the quality of interactions with providers, and expectations for their care may explain group reported access differences.

Perception of racial barriers to health care in the rural South.

We assessed how commonly people in the rural South perceive racial barriers to care, the characteristics of the people among whom this perception is most common and whether this perception is associated with satisfaction with and use of health services. We analyzed telephone survey data collected in 2002-3, using weighted statistical techniques and multivariate logistic regression in analyses stratified by race. Fifty-four percent of African Americans and 23% of Whites reported that they perceive racial barriers to care in their communities. African Americans who were middle-aged or older, male, or who report being in good-to-excellent health were more likely to perceive racial barriers. Whites who were younger, less educated, and uninsured were more likely than other Whites to perceive racial barriers. For African Americans, perceptions of racial barriers were associated with lower likelihood of being satisfied with care, but not with use of preventive services. The perception of racial barriers to health care is prevalent in the rural South, especially among African Americans. The consequences of this perception may include mistrust and dissatisfaction with medical care.

Life-course socioeconomic position and obesity in African American Women: the Pitt County Study.

OBJECTIVES: We studied obesity in African American women in relationship to their socioeconomic position (SEP) in childhood and adulthood. METHODS: On the basis of parents' occupation, we classified 679 women in the Pitt County (North Carolina) Study into low and high childhood SEP. Women's education, occupation, employment status, and home ownership were used to classify them into low and high adulthood SEP. Four life-course SEP categories resulted: low childhood/low adulthood, low childhood/high adulthood, high childhood/low adulthood, and high childhood/high adulthood. RESULTS: The odds of obesity were twice as high among women from low versus high childhood SEP backgrounds, and 25% higher among women of low versus high adulthood SEP. Compared to that in women of high SEP in both childhood and adulthood, the odds of obesity doubled for low/low SEP women, were 55% higher for low/high SEP women, and were comparable for high/low SEP women. CONCLUSIONS: Socioeconomic deprivation in childhood was a strong predictor of adulthood obesity in this community sample of African American women. Findings are consistent with both critical period and cumulative burden models of life-course socioeconomic deprivation and long-term risk for obesity in African American women.

Prevention and treatment of overweight in children and adolescents.

Overweight in childhood and adolescence is an important public health issue because of its rapidly increasing prevalence and associated adverse medical and social consequences. Recent studies have estimated that 15 percent of children in the United States are at risk for overweight, and an additional 15 percent are overweight. Important predictors of overweight include age, sex, race/ethnicity, and parental weight status. Generally, school-based prevention programs are not successful in reducing the prevalence of obesity. Treatment interventions include behavioral therapy, reduction in sedentary behavior, and nutrition and physical activity education. These interventions are moderately successful but may not be generalized to the primary care setting. Family physicians should focus on identifying at-risk and overweight children and adolescents at an early stage and educating families about the health consequences of being overweight. Interventions should be tailored to the patient and involve the entire family.

Exercise tolerance testing to screen for coronary heart disease: a systematic review for the technical support for the U.S. Preventive Services Task Force.

BACKGROUND: Coronary heart disease is the leading cause of morbidity and mortality in the United States. Exercise tolerance testing has been proposed as a means of better identifying asymptomatic patients at high risk for coronary heart disease events. PURPOSE: To review the evidence on the use of exercise tolerance testing to screen adults with no history of cardiovascular disease for coronary heart disease. DATA SOURCES: The MEDLINE database from 1966 through February 2003, hand-searching of bibliographies, and expert input. STUDY SELECTION: Eligible studies evaluated the benefits or harms of exercise tolerance testing when added to traditional risk assessment for adults with no known history of cardiovascular events. DATA EXTRACTION: One reviewer extracted information from eligible articles into evidence tables, and another reviewer checked the tables. Disagreements were resolved by consensus. DATA SYNTHESIS: No study has directly examined the effect of screening asymptomatic patients with exercise tolerance testing on coronary heart disease outcomes or risk-reducing behaviors or therapies. Multiple cohort studies demonstrate that screening exercise tolerance testing identifies a small proportion of asymptomatic persons (up to 2.7% of those screened) with severe coronary artery obstruction who may benefit from revascularization. Several large prospective cohort studies, conducted principally in middle-aged men, suggest that exercise tolerance testing can provide independent prognostic information about the risk for future coronary heart disease events (relative risk with abnormal exercise tolerance testing, 2.0 to 5.0). However, when the risk for coronary heart disease events is low, most positive findings will be false and may result in unnecessary further testing or worry. The risk level at which the benefits of additional prognostic information outweigh the harms of false-positive results is unclear and requires further study. CONCLUSIONS: Although screening exercise tolerance testing detects severe coronary artery obstruction in a small proportion of persons screened and can provide independent prognostic information about the risk for coronary heart disease events, the effect of this information on clinical management and disease outcomes in asymptomatic patients is unclear.