Comparison of overall obesity and body fat distribution in predicting risk of mortality

The relationship between body size and mortality in the linked Scottish Health Surveys: cross-sectional surveys with follow-up

OBJECTIVE

To investigate the relationship between body mass index (BMI), waist circumference (WC) or waist-hip ratio (WHR) and all-cause mortality or cause-specific mortality.

DESIGN

Cross-sectional surveys linked to hospital admissions and death records.

SUBJECTS

In total, 20,117 adults (aged 18-86 years) from a nationally representative sample of the Scottish population.

MEASUREMENTS

Cox proportional hazards models were used to estimate hazard ratios (HRs) for all-cause, or cause-specific, mortality. The three anthropometric measurements BMI, WC and WHR were the main variables of interest. The following were adjustment variables: age, gender, smoking status, alcohol consumption, survey year, social class and area of deprivation.

RESULTS

BMI-defined obesity (≥ 30 kg m(-2)) was not associated with increased risk of mortality (HR = 0.93; 95% confidence interval = 0.80-1.08), whereas the overweight category (25-<30 kg m(-2)) was associated with a decreased risk (0.80; 0.70-0.91). In contrast, the HR for a high WC (men ≥ 102 cm, women ≥ 88 cm) was 1.17 (1.02-1.34) and a high WHR (men ≥ 1, women ≥ 0.85) was 1.34 (1.16-1.55). There was an increased risk of cardiovascular disease (CVD) mortality associated with BMI-defined obesity, a high WC and a high WHR categories; the HR estimates for these were 1.36 (1.05-1.77), 1.41 (1.11-1.79) and 1.44 (1.12-1.85), respectively. A low BMI (<18.5 kg m(-2)) was associated with elevated HR for all-cause mortality (2.66; 1.97-3.60), for chronic respiratory disease mortality (3.17; 1.39-7.21) and for acute respiratory disease mortality (11.68; 5.01-27.21). This pattern was repeated for WC but not for WHR.

CONCLUSIONS

It might be prudent not to use BMI as the sole measure to summarize body size. The alternatives WC and WHR may more clearly define the health risks associated with excess body fat accumulation. The lack of association between elevated BMI and mortality may reflect the secular decline in CVD mortality.

Independent effects of age-related changes in waist circumference and BMI z scores in predicting cardiovascular disease risk factors in a prospective cohort of adolescent females

BACKGROUND

Cross-sectional data indicate that central adiposity is associated with cardiovascular disease risk, independent of total adiposity. The use of longitudinal data to investigate the relation between changes in fat distribution and the emergence of risk factors is limited.

OBJECTIVE

We tested the hypothesis that age-related change in waist circumference (to reflect central adiposity) during adolescence is a significant predictor of longitudinal change in cardiovascular disease risk, after adjustment for change in body mass index (BMI) z score (to reflect total adiposity) in a cohort of postmenarcheal adolescent females. We also tested whether race modified this relation.

DESIGN

We analyzed publicly available data from the National Heart, Lung, and Blood Institute Growth and Health Study. Longitudinal regression models were fitted to investigate the independent effects of changes in waist circumference on cardiovascular disease risk factors.

RESULTS

Steeper age-related increases in waist circumference over time were associated with a greater increase in LDL-cholesterol concentrations, systolic blood pressure, diastolic blood pressure, and homeostasis model assessment of insulin resistance, after adjustment for BMI z score, in white but not in black females. Change in waist circumference was not a statistically significant predictor of age-related changes in HDL-cholesterol, triglyceride, insulin, and glucose concentrations, after adjustment for changes in BMI z score, in either white or black females.

CONCLUSIONS

Our research suggests that monitoring waist circumference in addition to BMI z score has the potential to identify adolescents at risk of the emergence of cardiovascular disease risk factors, at least in white females. The data also suggest that race may modify the relation between fat distribution pattern and cardiovascular disease risk factors.

Intra-individual changes in body weight in population-based cohorts during four decades: the Finnish FINRISK study

BACKGROUND

The aim of the study was to evaluate trends in intra-individual weight changes over the last four decades in Finland.

METHODS

Within the eight FINRISK surveys conducted during the years 1972-2007, we identified individuals who had participated, by chance in at least two surveys. First, individuals aged 25-54 years who had undergone a health examination within 10 years of the first examination (n = 2033) were categorized into five cohorts covering different time periods, and the annual weight change was calculated at follow-up. Second, for each individual aged 25-69 years the longest possible follow-up time (5-35 years) was identified (n = 3443), and the corresponding annual weight change was evaluated.

RESULTS

Comparing the five cohorts from different time periods, the annual increase in body weight among men between 25- and 54-year old remained stable in the range of 0.27-0.47 kg per year over the decades, whereas women belonging to the most recent cohorts (the 1990s) gained weight at 0.53-0.63 kg per year, which is more than double the oldest cohort's weight gain of 0.24 kg. Overall, the annual increase in weight was around 0.3 kg in both sexes. The younger participants had a stronger tendency to gain weight than the older, and those with BMI < 25 kg/m(2) gained more than overweight or obese individuals.

CONCLUSION

The amount of intra-individual annual increase in body weight among men remained stable over the decades, while it increased among women. The tendency to gain weight was most pronounced among the youngest and among those initially leanest.

How is the risk of undernutrition associated with cardiovascular disease among individuals of advanced age?

BACKGROUND

The oldest old (85+) are the fastest growing population segment in New Zealand. Cardiovascular disease (CVD) is the main cause of death and is associated with various risk factors including risk of undernutrition.

OBJECTIVES

To determine if there is an association between CVD and nutrition risk in advanced age.

SETTING

Three North Island locations (rural and urban areas) in New Zealand.

PARTICIPANTS

108 participants aged 85 years (75-79 for Maori).

MEASUREMENTS

Comprehensive health assessments were undertaken. Clinically manifest CVD was pre-defined and ascertained from interviews and hospitalisation records. Nutrition risk was assessed using a validated questionnaire-Seniors in the Community: Risk evaluation for eating and nutrition, Version II (SCREEN II).

RESULTS

72 participants (67%) had CVD (49% men); 52% of participants had a SCREEN II score < 50. Those with CVD had lower HDL level [median(IQR)] [1.4(0.7) vs. 1.6(0.6)] (p=0.041), and higher waist circumference [97.5(19.1) vs. 89.3(20.6)] (p=0.043) compared to those without CVD. Those with CVD were at no greater nutrition risk than those without CVD (SCREEN II score: [49(7) vs. 51(10)] (p=0.365). Using logistic regression controlling for confounders, SCREEN II scores trended towards an inverse association with CVD (p=0.10).

CONCLUSION

Two thirds of the study participants had CVD and half were at risk of undernutrition. Nutrition risk was mildly associated with CVD. This study provides further evidence that those in advanced age are at risk of undernutrition. Further research is needed to establish how the causes and consequences of CVD are related to nutrition risk.

Inflammation and biochemical features of bariatric candidates: does gender matter?

BACKGROUND

Accumulated fat is an accepted trigger of inflammation and metabolic syndrome but specific biochemical associations in males and females are still debated. In a prospective study, multiple variables were analyzed to search for gender-related correlations.

METHODS

Bariatric candidates (n = 94) were consecutively investigated. Age was 34.9 ± 10.4 years (68.1% females) and body mass index (BMI) was 40.8 ± 4.6 kg/m(2). Methods included anthropometrics, inflammatory indices (C-reactive protein (CRP), white blood cell count (WBC), ferritin) and general biochemical profile.

RESULTS

Ferritin, but not CRP or WBC, was substantially more elevated in males. Serum albumin, uric acid, creatinine, and liver enzymes AST and ALT were also higher in men. Even after BMI was adjusted, all differences remained significant, and several, notably ferritin, withstood waist circumference control. Ferritin and CRP correlated with anthropometrics, glucose-related measurements, and liver enzymes, whereas WBC was only associated with triglycerides in females.

CONCLUSIONS

(1) Males displayed more severe inflammation according to ferritin profile, and also more signs of liver derangement; (2) all differences continued after BMI discrepancies were adjusted for, and ferritin was significant also after control of waist girth; (3) in both genders inflammatory markers often correlated with different anthropometrics, liver enzymes, and markers of glucose homeostasis; and (4) inflammatory and biochemical gender-related dissimilarities might have prognostic implications for cardiovascular risk and other comorbidities, and deserve additional studies.

Childhood anxiety associated with low BMI in women with anorexia nervosa

OBJECTIVE

Extremely low body mass index (BMI) values are associated with increased risk for death and poor long-term prognosis in individuals with anorexia nervosa (AN). The present study explores childhood personality characteristics that could be associated with the ability to attain an extremely low BMI.

METHODS

Participants were 326 women from the Genetics of Anorexia Nervosa (GAN) Study who completed the Structured Interview for Anorexia Nervosa and Bulimic Syndromes and whose mother completed the Child Behavioral Checklist and/or Revised Dimensions of Temperament Survey.

RESULTS

Children who were described as having greater fear or anxiety by their mothers attained lower BMIs during AN (p < 0.02). Path analysis in the GAN and a validation sample, Price Foundation Anorexia Nervosa Trios Study, confirmed the relation between early childhood anxiety, caloric restriction, qualitative food item restriction, excessive exercise, and low BMI. Path analysis also confirmed a relation between childhood anxiety and caloric restriction, which mediated the relation between childhood anxiety and low BMI in the GAN sample only.

CONCLUSION

Fearful or anxious behavior as a child was associated with the attainment of low BMI in AN and childhood anxiety was associated with caloric restriction. Measures of anxiety and factors associated with anxiety-proneness in childhood may index children at risk for restrictive behaviors and extremely low BMIs in AN.

Obesity: focus on all-cause mortality and cancer

Excess body weight is a strong determinant as well as modifiable risk factor for all-cause and cancer mortality, and as such carries the potential for primary prevention. Recently published studies greatly enhance our knowledge about the impact of body fat distribution on relative risks specific to cancer type, and among women, there is further evidence for the role of menopausal status in modifying relative risks. However, the magnitude of all-cause as well as cancer mortality related to excess body weight varies between prospective cohort studies and the strength of the association, in particular in the overweight range, is still a matter of debate. The distribution of total body fat, how we measure it, and the ratio of body fat to fat-free mass explains to some degree the inconsistencies in associated disease risks in the literature. Physical activity, a potential confounder, has been shown to lower the risk of many chronic diseases, independently of the degree of adiposity. A review of the literature provides much support for public health messages that advocate the benefit of change to a more active lifestyle regardless of age and level of excess body fat.

Waist-hip-ratio as a predictor of all-cause mortality in high-functioning older adults

PURPOSE

The relationship between obesity and mortality in older adults is debated, with concern that body mass index (BMI) may be an imperfect measure of obesity in this age group. We assessed the relationship between three measures of obesity and all-cause mortality in a group of healthy older adults.

METHODS

We analyzed data from the MacArthur Successful Aging Study, a longitudinal study of high-functioning men and women, ages 70-79 years at baseline. We examined 12-year, all-cause mortality risk by BMI, waist circumference, and waist-to-hip circumference ratio (WHR). Proportional hazards regression was used to adjust for gender, race, baseline age, and smoking status. We tested for obesity interactions with gender, race, and smoking status and conducted stratified analyses based on the results of interaction testing.

RESULTS

There was no association between all-cause mortality and BMI or waist circumference in either unadjusted or adjusted analyses. In contrast, all-cause mortality increased with WHR. There was an interaction with sex, so that there was a graded relationship between WHR and mortality in women (relative hazard, 1.28 per 0.1 increase in WHR; 95% confidence interval, 1.05-1.55) and a threshold relationship in men (relative hazard 1.75 for WHR>1.0 compared to WHR< or =1.0; 95% confidence interval, 1.06-2.91).

CONCLUSION

WHR rather than BMI appears to be the more appropriate yardstick for risk stratification of high-functioning older adults.

Raised adolescent body mass index predicts the development of adiposity and a central distribution of body fat in adulthood: a longitudinal study

OBJECTIVE

To test the hypothesis that adolescent body mass index (BMI) tracks into adulthood and can be used as a predictor of obesity and/or central adiposity in adulthood.

METHOD

A prospective cohort study following up 111 female and 84 male subjects who participated in dietary and anthropometric surveys when aged 12 years (in 1979-1981) and 33 years (in 2000-2001). At both time points, height and weight were measured and BMI calculated. At 33 years, waist circumference (WC) and hip circumference were also measured and waist-to-hip ratio (WHR) calculated.

RESULTS

In the male and female participants, BMI at 12 years was associated significantly with BMI at 33 years (R = 0.58 and 0.53, respectively, both p < 0.01) and WC at 33 years (R = 0.58 and 0.53, both p < 0.01). The probability of being an obese adult increased with rising adolescent BMI: normal weight male (BMI < 20.89 kg/m(2)) and female subjects (BMI < 21.20 kg/m(2)) at 12 years had a 20% and a 7% chance of being obese at 33 years, respectively; the probabilities for obese male (BMI > or =25.58 kg/m(2)) and female subjects (BMI > or =26.05 kg/m(2)) were 83 and 64%. The corresponding probability of becoming centrally obese (measured by WC) increased from 17 and 16% in male and female subjects of a normal weight to 58 and 59% in those being obese.

CONCLUSIONS

Adolescent BMI is a good predictor of adult BMI and WC and the likelihood of becoming obese and/or centrally obese in adulthood.