Does cigarette smoking modify the association between change in body mass index during young adulthood and risk of coronary mortality during middle-age in men? Twenty-five year follow-up results from the Chicago Western Electric Study

Many persons in the U.S. gain weight during young adulthood, and the prevalence of obesity has been increasing among young adults. Although obesity and physical inactivity are generally recognized as risk factors for coronary heart disease (CHD), the magnitude of their effect on risk may have been seriously underestimated due to failure to adequately handle the problem of cigarette smoking. Since cigarette smoking causes weight loss, physically inactive cigarette smokers may remain relatively lean because they smoke cigarettes. We hypothesize cigarette smoking modifies the association between weight gain during young adulthood and risk of coronary heart disease during middle age, and that the true effect of weight gain during young adulthood on risk of CHD can be assessed only in persons who have not smoked cigarettes. Specifically, we hypothesize that weight gain during young adulthood is positively associated with risk of CHD during middle-age in nonsmokers but that the association is much smaller or absent entirely among cigarette smokers. The purpose of this study was to test this hypothesis. The population for analysis was comprised of 1,934 middle-aged, employed men whose average age at the baseline examination was 48.7 years. Information collected at the baseline examinations in 1958 and 1959 included recalled weight at age 20, present weight, height, smoking status, and other CHD risk factors. To decrease the effect of intraindividual variation, the mean values of the 1958 and 1959 baseline examinations were used in analyses. Change in body mass index ($\Delta$BMI) during young adulthood was the primary exposure variable and was measured as BMI at baseline (kg/m$\sp2)$ minus BMI at age 20 (kg/m$\sp2).$ Proportional hazards regression analysis was used to generate relative risks of CHD mortality by category of $\Delta$BMI and cigarette smoking status after adjustment for age, family history of CVD, major organ system disease, BMI at age 20, and number of cigarettes smoked per day. Adjustment was not performed for systolic blood pressure or total serum cholesterol as these were regarded as intervening variables. Vital status was known for all men on the 25th anniversary of their baseline examinations. 705 deaths (including 319 CHD deaths) occurred over 40,136 person-years of experience. $\Delta$BMI was positively associated with risk of CHD mortality in never-smokers, but not in ever-smokers (p for interaction = 0.067). For never-smokers with $\Delta$BMI of stable, low gain, moderate gain, and high gain, adjusted relative risks were 1.00, 1.62, 1.61, and 2.78, respectively (p for trend = 0.010). For ever-smokers, with $\Delta$BMI of stable, low gain, moderate gain, and high gain, adjusted relative risks were 1.00, 0.74, 1.07, and 1.06, respectively (p for trend = 0.422). These results support the research hypothesis that cigarette smoking modifies the association between weight gain and CHD mortality. Current estimates of the magnitude of effect of obesity and physical inactivity on risk of coronary mortality may have been seriously underestimated due to inadequate handling of cigarette smoking. ^

The relationship between body image and physical activity in African American women

High rates of overweight and obesity in African American women have been attributed, in part, to poor health habits, such as physical inactivity, and cultural influences on body image perceptions. The purpose of this study was to determine the relationship among body mass index (BMI=kg/m2), body image perception (perceived and desired) and physical activity, both self-reported and objectively measured. Anthropometric measures of BMI and Pulvers' culturally relevant body image, physical activity and demographic data were collected from 249 African American women in Houston. Women ( M = 44.8 yrs, SD = 9.5) were educated (53% college graduates) and were overweight (M = 35.0 kg/m2, SD = 9.2). Less than half of women perceived their weight correctly regardless of their actual weight (p < 0.001). Nearly three-fourths (73.9%) of women who were normal weight desired to be obese, and only 39.4% of women desired to be normal weight, regardless of actual or perceived weight. Women in all weight classes (normal, overweight and obese) varied in objective measures of physical activity (F(2,112) = 4.424, p = .014). Regression analyses showed objectively measured physical activity was significantly associated with BMI ( Beta = -2.45, p < .01) and self-reported walking was significantly associated with perceived BMI (Beta = -.156, p = .017). Results suggest African American women who are smaller want to be larger and African American women who are larger want to be smaller, revealing dichotomous distortion in body images. Low rates of physical activity may be a factor. Research is needed to increase physical activity levels in African American women, leading to improved satisfaction with normal weight as desirable for health and beauty. Supported by NCI (NIH) 1R01CA109403. ^

The association between CD4+ lymphocyte count and measures of body composition in HIV-infected men

Purpose. This project was designed to describe the association between wasting and CD4 cell counts in HIV-infected men in order to better understand the role of wasting in progression of HIV infection.^ Methods. Baseline and prevalence data were collected from a cross-sectional survey of 278 HIV-infected men seen at the Houston Veterans Affairs Medical Center Special Medicine Clinic, from June 1, 1991 to January 1, 1994. A follow-up study was conducted among those at risk, to investigate the incidence of wasting and the association between wasting and low CD4 cell counts. Wasting was described by four methods. Z-scores for age-, sex-, and height-adjusted weight; sex-, and age-adjusted mid-arm muscle circumference (MAMC); and fat-free mass; and the ratio of extra-cellular mass (ECM) to body-cell mass (BCM) $>$ 1.20. FFM, ECM, and BCM were estimated from bioelectrical impedance analysis. MAMC was calculated from triceps skinfold and mid-arm circumference. The relationship between wasting and covariates was examined with logistic regression in the cross-sectional study, and with Poisson regression in the follow-up study. The association between death and wasting was examined with Cox's regression.^ Results. The prevalence of wasting ranged from 5% (weight and ECM:BCM) to almost 14% (MAMC and FFM) among the 278 men examined. The odds of wasting, associated with baseline CD4 cell count $<$200, was significant for each method but weight, and ranged from 4.6 to 12.7. Use of antiviral therapy was significantly protective of MAMC, FFM and ECM:BCM (OR $\approx$ 0.2), whereas the need for antibacterial therapy was a risk (OR 3.1, 95% CI 1.1-8.7). The average incidence of wasting ranged from 4 to 16 per 100 person-years among the approximately 145 men followed for 160 person-years. Low CD4 cell count seemed to increase the risk of wasting, but statistical significance was not reached. The effect of the small sample size on the power to detect a significant association should be considered. Wasting, by MAMC and FFM, was significantly associated with death, after adjusting for baseline serum albumin concentration and CD4 cell count.^ Conclusions. Wasting by MAMC and FFM were strongly associated with baseline CD4 cell counts in both the prevalence and incidence study and strong predictors of death. Of the two methods, MAMC is convenient, has available reference population data, may be the most appropriate for assessing the nutritional status of HIV-infected men. ^

Associations of perceived body image and subjective social status with levels of physical activity in Mexican American adolescents

The current study is a secondary data analysis of a prospective cohort study that examined demographic and psychosocial variables and their associations with physical activity levels in Mexican-American adolescents in Houston, Texas. Body image, subjective social status, and anxiety were the main variables of interest. The sample included 952 unrelated Mexican-American adolescents in Houston, Texas. The majority (84.2%) of the study population did not meet physical activity standards prescribed by the CDC.^ In a multivariate model controlling for age, socioeconomic status, gender, general body image, preferred body image, subjective social status, and anxiety, gender and subjective social status were found to be the strongest determinants of physical activity levels. Males and those with a high subjective social status were more likely to participate in physical activity than those with low subjective status. Lower levels of anxiety and a more positive body image were also found to be associated with higher levels of physical activity. In multivariate analyses gender and subjective social status showed the strongest associations with physical activity.^

The association of peer victimization and/or bullying perpetration and body dissatisfaction in elementary students from the healthy passages baseline study

This is the first U.S. study to investigate the association between peer victimization and/or bullying perpetration and body image dissatisfaction in American elementary school students. The study used data collected from the Healthy Passages baseline cohort of 5152 ethnically diverse fifth grade students from Alabama, Texas, and California. The overall prevalence of body dissatisfaction in our fifth grade sample was 50%. Students who were dissatisfied with their bodies were 23% more likely to be involved in peer victimization than students who were satisfied with their bodies (OR = 1.23; 95% CI = 1.02, 1.48). No significant associations were found between bullying status or bully-victim status and body dissatisfaction. Other factors that contributed significantly to a student's body image status were BMI, level of self-worth, level of household income, gender, pubertal timing and support received from adults (other than parents). It is noteworthy that those who were dissatisfied were heavier, came from lower income homes and were more likely to be male. Additional longitudinal studies are needed to confirm these associations, especially among large ethnically and socio-economically diverse samples. ^

Body image rating scales to assess obesity

Obesity prevalence in the U.S. has increased during the last three decades with major impact on public health. Screening for obesity in a population with unknown weight status can be time- and resource-consuming, but the information is valuable for prioritizing and allocating scarce resources. The challenge remains to properly assess obesity with the available methods. Body Image Rating Scales (BIRS) have initially been developed to assess body image disturbances, but also seem useful as an alternative method in assessing obesity prevalence. Several different BIRS exists. In this project I reviewed the literature that exists regarding the use of BIRS, and its advantages and limitations for the assessment of obesity status with regards to BMI. The result yielded nine publications that examined eight different scales and their correlation with BMI, ranging from r=.59 for self-reported BMI to r=.94 for measured BMI. One concern is the lack of standardization of this method to assess obesity, given the range of different scales. While many methods for obesity assessment are available, the simplicity, ease of use and cost-effectiveness of BIRS make it very appealing. BIRS remain a potentially attractive option to assess the weight status of a large population with minimal requirements in assets and time, especially in situations where measuring instruments are not available, or when height or weight could not be recalled.^

Adult weight gain and risk of colon cancer in men

Previous research supports the hypothesis that a "rich" diet (i.e., high in fat and low in fiber) increases the risk of colon cancer. Previous research also supports the hypothesis that physical inactivity increases the risk of colon cancer, perhaps because physical inactivity decreases gut motility, thereby increasing tee time that carcinogens are in contact with the intestinal mucosa. Habitual physical inactivity, combined with rich diet, ordinarily results in chronic energy imbalance and gain in weight, except when energy balance is modified by disease or factors such as cigarette smoking. Cigarette smokers typically stay lean because of effects of smoking on the resting metabolic rate as well as on efficiency of caloric intake and storage. Therefore, if physical inactivity and rich diet do increase the risk of colon cancer, then weight gain during young adulthood should be positively associated with incidence of colon cancer during later life, especially in nonsmokers.^ This hypothesis was investigated in a cohort of 2,059 randomly selected middle-aged men who were employed at the Western Electric Company in Chicago and were free of clinically diagnosed cancer at initial examination in 1958. Body mass index (BMI) in middle age was calculated from measured height and weight at the initial examination. BMI at age 20 was estimated from weight at age 20 as recalled at the initial examination and height as measured at the initial examination. Change in BMI between age 20 and middle age was estimated by subtracting the BMI at 20 from the BMI in middle age. Forty-nine incident cases of colon cancer were detected during 25 years (43,326 person-years) at risk. When stratified by level of change in BMI from age 20 to middle age ($\le$1.9, 2.0-3.9, 4.0-5.9, $\ge$6.0 kg/m$\sp2$), age-adjusted relative hazards of colon cancer in never-smokers were 1.00, 1.22, 2.31, and 5.01, respectively (p for trend = 0.008); corresponding values in ever-smokers were 1.00, 0.95, 0.77, and 0.87, These associations did not change appreciably after further adjustment for BMI at age 20, subscapular-triceps skinfold ratio, cigarette smoking, consumption of alcohol, energy, fat, and calcium.^ We also investigated the hypothesis that the risk of colon cancer was higher in men who were lean at age 20 and became fat by middle age (lean-to-fat) than in men who were fat at age 20 and stayed fat in middle-age (fat-to-fat). "Lean" was defined as BMI $<$24 kg/m$\sp2$ at age 20 and as BMI $<$27.0 kg/m$\sp2$ in middle age. Among never-smokers, in comparison to men who were lean at age 20 and in middle age (lean-to-lean), the age-adjusted relative hazard of colon cancer was 1.43 in the fat-to-fat group (95% confidence interval (CI) 0.37-5.52) and 3.36 in the lean-to-fat group (95% CI 1.21-9.37). This investigation provides new results on the magnitude of risk of colon cancer associated with weight gain during adulthood (from age 20 to middle age). This relation was obscured or underestimated in previous studies due to effect-modification by cigarette smoking. Finally, the result supports the idea that a life-style characterized by chronic energy imbalance during young adulthood increases risk of colon cancer. ^

Examining the Relationship Between Media Use and Aggression, Sexuality, and Body Image

Objectives: The primary purpose of this research is to understand the media's impact on individual attitudes and behaviors related to aggression, sexuality, and body image. This research is of particular importance because it uses up-to-date data reflecting effects based on the current media environment. Additionally, it includes a racially diverse sample. Methods: A survey of 407 students at a large, public university was conducted. The survey instrument contained general measures related to media consumption, including overall television, video game, and internet use, as well as more specific questions related to particular types of media, such as pornography. For the dependent variables, questions were included that measured both attitudes and behaviors related to aggression, sexuality, and body image. Results: Consistent with predictions, media use impacted both attitudes and behaviors related to aggression, sexuality, and body image. Specifically, overall television consumption led to increased levels of aggression (r=.18, pr=.20, pr=.24, pr=.42, pr=.40, p Conclusions: The media continue to play an important role in the development of attitudes and behaviors. It is warranted, therefore, to continue to investigate what media can cause negative outcomes, as well as to determine how those outcomes vary based on race and gender.

THE RELATIONSHIP BETWEEN OBESITY AND PSYCHOLOGICAL GENERAL WELL-BEING IN UNITED STATES WOMEN

While clinical studies have shown a negative relationship between obesity and mental health in women, population studies have not shown a consistent association. However, many of these studies can be criticized regarding fatness level criteria, lack of control variables, and validity of the psychological variables.^ The purpose of this research was to elucidate the relationship between fatness level and mental health in United States women using data from the First National Health and Nutrition Examination Survey (NHANES I), which was conducted on a national probability sample from 1971 to 1974. Mental health was measured by the General Well-Being Schedule (GWB), and fatness level was determined by the sum of the triceps and subscapular skinfolds. Women were categorized as lean (15th percentile or less), normal (16th to 84th percentiles), or obese (85th percentile or greater).^ A conceptual framework was developed which identified the variables of age, race, marital status, socioeconomic status (education), employment status, number of births, physical health, weight history, and perception of body image as important to the fatness level-GWB relationship. Multiple regression analyses were performed separately for whites and blacks with GWB as the response variable, and fatness level, age, education, employment status, number of births, marital status, and health perception as predictor variables. In addition, 2- and 3-way interaction terms for leanness, obesity and age were included as predictor variables. Variables related to weight history and perception of body image were not collected in NHANES I, and thus were not included in this study.^ The results indicated that obesity was a statistically significant predictor of lower GWB in white women even when the other predictor variables were controlled. The full regression model identified the young, more educated, obese female as a subgroup with lower GWB, especially in blacks. These findings were not consistent with the previous non-clinical studies which found that obesity was associated with better mental health. The social stigma of being obese and the preoccupation of women with being lean may have contributed to the lower GWB in these women. ^

Predictors of weight stability in women and men: The aerobic center longitudinal study, 1987--1995

It is estimated that more than half the U.S. adult population is overweight or obese as classified by a body mass index of 25.0–29.9 or ≥30 kg/m 2, respectively. Since the current treatment approaches for long-term maintenance of weight loss are lacking, the National Institutes of Health state that an effective approach may be to focus on weight gain prevention. There is a limited body of literature describing how adults maintain a stable weight as they age. It is hypothesized that weight stability is the result of a balance between energy consumption and energy expenditure as influenced by diet, lifestyle, behavior, genetics and environment. The purpose of this research was to examine the dietary intake and behaviors, lifestyle habits, and risk factors for weight change that predict weight stability in a cohort of 2101 men and 389 women aged 20 to 8 7 years in the Aerobic Center Longitudinal Study regardless of body weight at baseline. At baseline, participants completed a maximal exercise treadmill test to determine cardiorespiratory fitness, a medical history questionnaire, which included self-reported measures of weight, dietary behaviors, lifestyle habits, and risk factors for weight change, a three-day diet record, and a mail-back version of the medical history questionnaire in 1990 or 1995. All analyses were performed separately for men and women. Results from multivariate regression analyses indicated that the strongest predictor of follow-up weight for men and women was previous weight, accounting for 87.0% and 81.9% of the variance, respectively. Age, length of follow-up and eating habits were also significant predictors of follow-up weight in men, though these variables only explained 3% of the variance. For women, length of follow-up and currently being on a diet were significantly associated with follow-up weight but these variables explained only an additional 2% of the variance. Understanding the factors that influence weight change has tremendous public health importance for developing effective methods to prevent weight gain. Since current weight was the strongest predictor of previous weight, preventing initial weight gain by maintaining a stable weight may be the most effective method to combat the increasing prevalence of overweight and obesity. ^

Changes in serum lipids with change and fluctuation in body mass index and body fat distribution in Mexican Americans with type 2 diabetes

This dissertation was written in the format of three journal articles. Paper 1 examined the influence of change and fluctuation in body mass index (BMI) over an eleven-year period, on changes in serum lipid levels (total, HDL, and LDL cholesterol, triglyceride) in a population of Mexican Americans with type 2 diabetes. Linear regression models containing initial lipid value, BMI and age, BMI change (slope of BMI), and BMI fluctuation (root mean square error) were used to investigate associations of these variables with change in lipids over time. Increasing BMI over time was associated with gains in total and LDL cholesterol and triglyceride levels in women. Fluctuation of BMI was not associated with detrimental lipid profiles. These effects were independent of age and were not statistically significant in men. In Mexican-American women with type 2 diabetes, weight reduction is likely to result in more favorable levels of total and LDL cholesterol and triglyceride, without concern for possible detrimental effects of weight fluctuation. Weight reduction may not be as effective in men, but does not appear to be harmful either. ^ Paper 2 examined the associations of upper and total body fat with total cholesterol, HDL and LDL cholesterol, and triglyceride levels in the same population. Multilevel analysis was used to predict serum lipid levels from total body fat (BMI and triceps skinfold) and upper body fat (subscapular skinfold), while controlling for the effects of sex, age and self-correlations across time. Body fat was not strikingly associated with trends in serum lipid levels. However, upper body fat was strongly associated with triglyceride levels. This suggests that loss of upper body fat may be more important than weight loss in management of the hypertriglyceridemia commonly seen in type 2 diabetes. ^ Paper 3 was a review of the literature reporting associations between weight fluctuation and lipid levels. Few studies have reported associations between weight fluctuation and total, LDL, and HDL cholesterol and triglyceride levels. The body of evidence to date suggests that weight fluctuation does not strongly influence levels of total, LDL and HDL cholesterol and triglyceride. ^

Selection of body fat distribution indices in adults and associations with plasma lipid metabolism variables

Body fat distribution is a cardiovascular health risk factor in adults. Body fat distribution can be measured through various methods including anthropometry. It is not clear which anthropometric index is suitable for epidemiologic studies of fat distribution and cardiovascular disease. The purpose of the present study was to select a measure of body fat distribution from among a series of indices (those traditionally used in the literature and others constructed from the analysis) that is most highly correlated with lipid-related variables and is independent of overall fatness. Subjects were Mexican-American men and women (N = 1004) from a study of gallbladder disease in Starr County, Texas. Multivariate associations were sought between lipid profile measures (lipids, lipoproteins, and apolipoproteins) and two sets of anthropometric variables (4 circumferences and 6 skinfolds). This was done to assess the association between lipid-related measures and the two sets of anthropometric variables and guide the construction of indices.^ Two indices emerged from the analysis that seemed to be highly correlated with lipid profile measures independent of obesity. These indices are: 2*arm circumference-thigh skinfold in pre- and post-menopausal women and arm/thigh circumference ratio in men. Next, using the sum of all skinfolds to represent obesity and the selected body fat distribution indices, the following hypotheses were tested: (1) state of obesity and centrally/upper distributed body fat are equally predictive of lipids, lipoproteins and apolipoproteins, and (2) the correlation among the lipid-related measures is not altered by obesity and body fat distribution.^ With respect to the first hypothesis, the present study found that most lipids, lipoproteins and apolipoproteins were significantly associated with both overall fatness and anatomical location of body fat in both sex and menopausal groups. However, within men and post-menopausal women, certain lipid profile measures (triglyceride and HDLT among post-menopausal women and apos C-II, CIII, and E among men) had substantially higher correlation with body fat distribution as compared with overall fatness.^ With respect to the second hypothesis, both obesity and body fat distribution were found to alter the association among plasma lipid variables in men and women. There was a suggestion from the data that the pattern of correlations among men and post-menopausal women are more comparable. Among men correlations involving apo A-I, HDLT, and HDL$\sb2$ seemed greatly influenced by obesity, and A-II by fat distribution; among post-menopausal women correlations involving apos A-I and A-II were highly affected by the location of body fat.^ Thus, these data point out that not only can obesity and fat distribution affect levels of single measures, they also can markedly influence the pattern of relationship among measures. The fact that such changes are seen for both obesity and fat distribution is significant, since the indices employed were chosen because they were independent of one another. ^

Maximal exercise hemodynamics and risk of mortality in apparently healthy men and women

The use of exercise electrocardiography (ECG) to detect latent coronary heart disease (CHD) is discouraged in apparently healthy populations because of low sensitivity. These recommendations however, are based on the efficacy of evaluation of ischemia (ST segment changes) with little regard for other measures of cardiac function that are available during exertion. The purpose of this investigation was to determine the association of maximal exercise hemodynamic responses with risk of mortality due to all-causes, cardiovascular disease (CVD), and coronary heart disease (CHD) in apparently healthy individuals. Study participants were 20,387 men (mean age = 42.2 years) and 6,234 women (mean age = 41.9 years) patients of a preventive medicine center in Dallas, TX examined between 1971 and 1989. During an average of 8.1 years of follow-up, there were 348 deaths in men and 66 deaths in women. In men, age-adjusted all-cause death rates (per 10,000 person years) across quartiles of maximal systolic blood pressure (SBP) (low to high) were: 18.2, 16.2, 23.8, and 24.6 (p for trend $<$0.001). Corresponding rates for maximal heart rate were: 28.9, 15.9, 18.4, and 15.1 (p trend $<$0.001). After adjustment for confounding variables including age, resting systolic pressure, serum cholesterol and glucose, body mass index, smoking status, physical fitness and family history of CVD, risks (and 95% confidence interval (CI)) of all-cause mortality for quartiles of maximal SBP, relative to the lowest quartile, were: 0.96 (0.70-1.33), 1.36 (1.01-1.85), and 1.37 (0.98-1.92) for quartiles 2-4 respectively. Similar risks for maximal heart rate were: 0.61 (0.44-0.85), 0.69 (0.51-0.93), and 0.60 (0.41-0.87). No associations were noted between maximal exercise rate-pressure product mortality. Similar results were seen for risk of CVD and CHD death. In women, similar trends in age-adjusted all-cause and CVD death rates across maximal SBP and heart rate categories were observed. Sensitivity of the exercise test in predicting mortality was enhanced when ECG results were evaluated together with maximal exercise SBP or heart rate with a concomitant decrease in specificity. Positive predictive values were not improved. The efficacy of the exercise test in predicting mortality in apparently healthy men and women was not enhanced by using maximal exercise hemodynamic responses. These results suggest that an exaggerated systolic blood pressure or an attenuated heart rate response to maximal exercise are risk factors for mortality in apparently healthy individuals. ^