Adiposity, adipose tissue distribution and mortality rates in the Canada Fitness Survey follow-up study

Mortality risk relationship using standard categorized BMI or knee-height based BMI - does the overweight/lower mortality paradox hold true?

BACKGROUND

The body mass index (BMI) is prone to misclassification of obesity due to age-related height loss and resulting measurement errors. Knee-height based BMI (KH-BMI) has not been previously studied in relation to mortality risk in older adults.

AIM

To evaluate the age- and sex-specific mortality risk relationship using classic BMI and knee height predicted BMI (KH-BMI) overweight and obesity in a 15-year follow-up study including older Swedish adults aged 60-93 years.

METHODS

A 15-year follow-up study among 2,786 individuals aged ≥ 60 years. Height, weight and KH were measured. KH-predicted height was estimated using formulated gender-specific equations. Classic BMI and KH-BMI (kg/m2) were calculated. Mortality data was obtained from the Swedish death registry. Questionnaires were used to collect data on obesity-related lifestyle factors and comorbidities.

RESULTS

Cox regression revealed that using the classic BMI, when comparing with the normal/underweight reference group, there was a mortality risk among overweight men (HR = 0.67, 0.52-0.87), overweight women (HR = 0.79, 0.65-0.97), and obese men (HR = 0.60, 0.41-0.89) aged ≥ 80 years old. Using the KH-BMI, only overweight men and overweight women aged ≥ 80 years had a lower mortality risk, men (HR = 0.71, 0.55-0.92); women (HR = 0.77, 0.62-0.95) after adjusting for obesity-related lifestyle factors and comorbidities.

DISCUSSION

There is evidence that obesity is overestimated by the BMI, in comparison with the KH-BMI classification. In terms of mortality risk and after adjusting for height, there remains a paradoxical protective association between overweight and mortality.

CONCLUSION

Regardless of classic BMI or KH-BMI estimation, overweight men and women aged ≥ 80 years had a lower mortality risk compared to normal/underweight men and women ≥ 80 years.

Prevalence of central obesity and associated factors in Ethiopia: A systematic review and meta-analysis

INTRODUCTION

Obesity is a global public health concern that is now on the rise, especially in low- and middle-income nations. Despite the fact that there are several studies reporting the prevalence of central obesity among adults in Ethiopia, there is a lack of a systematic review and meta-analysis synthesizing the existing observational studies. Therefore, this systematic review and meta-analysis aimed to determine the prevalence of central obesity and its associated factors in Ethiopia.

METHODS

Online libraries such as PubMed, Google Scholar, Scopus, Science Direct, and Addis Ababa University were searched. Data were extracted using Microsoft Excel and analyzed using STATA statistical software (v. 16). Forest plots, Begg's rank test, and Egger's regression test were all used to check for publication bias. To look for heterogeneity, I² was computed, and an overall estimated analysis was carried out. Subgroup analysis was done by region and study setting. In addition, the pooled odds ratio for related covariates was calculated.

RESULTS

Out of 685 studies assessed, 20 met our criteria and were included in the study. A total of 12,603 people were included in the study. The prevalence of central obesity was estimated to be 37.31% [95% confidence interval (CI): 29.55-45.07]. According to subgroup analysis by study region and setting, the highest prevalence was observed in the Dire Dawa region (61.27%) and community-based studies (41.83%), respectively. Being a woman (AOR = 6.93; 95% CI: 3.02-10.85), having better socioeconomic class (AOR = 5.45; 95% CI: 0.56-10.34), being of age 55 and above (AOR = 5.23; 95% CI: 2.37-8.09), being physically inactive (AOR = 1.80; 95% CI: 1.37-2.24), being overweight (AOR = 4.00; 95% CI: 2.58-5.41), being obese (AOR = 6.82; 95% CI: 2.21-11.43), and having hypertension (AOR = 3.84; 95% CI: 1.29-6.40) were the factors associated with central obesity.

CONCLUSION

The prevalence of central obesity was high in Ethiopia. Being a woman, having a higher socioeconomic class, being older, being physically inactive, being overweight or obese, and having hypertension were all associated. Therefore, it is vital for the government and health organizations to design and implement preventive measures like early detection, close monitoring, and positive reversal of central obesity in all patients and the general population. High-quality investigations on the prevalence of central obesity in the Ethiopian people are required to better understand the status of central obesity in Ethiopia.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO, identifier: CRD42022329234.

Associations of Skeletal Muscle Mass and Fat Mass With Incident Cardiovascular Disease and All-Cause Mortality: A Prospective Cohort Study of UK Biobank Participants

Background There is debate whether body mass index is a good predictor of health outcomes because different tissues, namely skeletal muscle mass (SMM) and fat mass (FM), may be differentially associated with risk. We investigated the association of appendicular SMM (aSMM) and FM with fatal and nonfatal cardiovascular disease (CVD) and all-cause mortality. We compared their prognostic value to that of body mass index. Methods and Results We studied 356 590 UK Biobank participants aged 40 to 69 years with bioimpedance analysis data for whole-body FM and predicted limb muscle mass (to calculate aSMM). Associations between aSMM and FM with CVD and all-cause mortality were examined using multivariable Cox proportional hazards models. Over 3 749 501 person-years of follow-up, there were 27 784 CVD events and 15 844 all-cause deaths. In men, aSMM was positively associated with CVD incidence (hazard ratio [HR] per 1 SD 1.07; 95% CI, 1.06-1.09) and there was a curvilinear association in women. There were stronger positive associations between FM and CVD with HRs per SD of 1.20 (95% CI, 1.19-1.22) and 1.25 (95% CI, 1.23-1.27) in men and women respectively. Within FM tertiles, the associations between aSMM and CVD risk largely persisted. There were J-shaped associations between aSMM and FM with all-cause mortality in both sexes. Body mass index was modestly better at discriminating CVD risk. Conclusions FM showed a strong positive association with CVD risk. The relationship of aSMM with CVD risk differed between sexes, and potential mechanisms need further investigation. Body fat and SMM bioimpedance measurements were not superior to body mass index in predicting population-level CVD incidence or all-cause mortality.

Global, regional and time-trend prevalence of central obesity: a systematic review and meta-analysis of 13.2 million subjects

We aimed to examine the global prevalences of central obesity according to age, sex, race, place of residence, geographical region, national income level, and the definitions of central obesity. MEDLINE and Embase were searched. Studies with sample size of ≥ 500 and investigated individuals aged ≥ 15 years were included. Metaprop (a Stata command) was adopted to conduct a meta-analysis of prevalence, and the Freeman-Tukey Double Arcsine Transformation was used to stabilize the variances. A random-effects model was used to evaluate the prevalence and 95% confidence intervals (CI) of central obesity. There were 288 studies involving 13,233,675 individuals in this analysis. The overall prevalence of central obesity was 41.5% (95% CI 39.9–43.2%). A higher prevalence was found in older individuals, female subjects, urban residents, Caucasians, and populations of higher income level countries. Regarding regional variations, the highest prevalence was found in Sothern America (55.1%, 95% CI 45.8–64.3%) and Central American (52.9%, 95% CI 32.7–72.7%). Its prevalence was rapidly rising from 1985 to 2014. From 1985–1999 to 2010–2014, younger subjects aged 15–40 years showed a more drastic rise in prevalence (16.3 to 33.9%) than subjects aged > 40 years (43.6 to 57.9%). Male individuals have a more drastic rise (25.3 to 41.6%) than females (38.6 to 49.7%). Major increasing in prevalence of the condition in the past three decades, particularly in certain subgroups. These findings could act as a useful reference to inform public health strategies to minimize the impact of central obesity on population health.

Depression among Chinese Left-Behind Children: A systematic review and meta-analysis

BACKGROUND

In China, there are approximately 70 million children, nearly 25% of the child population, who are left behind in the care of other family members when their parents migrate to urban areas, for increased economic opportunities. This paper presents a systematic review and a meta-analysis of studies that have examined the phenomenon of depression among these left-behind children (LBC).

METHODS

Six hundred three papers published between 2000 and 2017 were retrieved from five databases (China National Knowledge Infrastructure, Wanfang, Weipu, PubMed, and Web of Science).

RESULTS

Twenty-one studies (18 in Chinese and 3 in English) met the criteria for inclusion in this meta-analysis. The pooled estimate of depression among LBC was 26.4%. A significant heterogeneity has been found in reported findings, and this heterogeneity was associated with three types of study characteristics, including using an unclear definition of LBC and using invalidated depression instruments, and the geographic location.

CONCLUSIONS

The risk of mental health problems among this large number of LBC suggests the need to quantify the extent and distribution of their mental health state. Implications for methodological improvements for future research have been discussed.

Waist Circumference and All-Cause Mortality Independent of Body Mass Index in Korean Population from the National Health Insurance Health Checkup 2009⁻2015

BACKGROUND

Waist circumference (WC) is an index of abdominal obesity and associated with co-morbidities and mortality. Higher WC is positively associated with increased mortality; therefore, we examined the relationship between WC and mortality in Korean populations with the interaction of body mass index (BMI) and WC for mortality.

METHODS

A total of 23,263,878 subjects (men = 11,813,850 and women = 11,450,028) who were older than 20 years and underwent the National Health Insurance Service health checkup were included. WC was divided into six categories by 5 cm increments and level 3 (85⁻90 cm in men and 80⁻85 cm in women) was referenced. Multivariable Cox proportional hazard models were used to obtain the hazard ratios (HRs) and 95% confidence intervals for all-cause mortality according to the six levels of WC.

RESULTS

WC in 5 cm increments showed a positively increased all-cause mortality after adjusting for all covariates including BMI. Men showed higher HRs for mortality than women as WC increased, and the HRs were higher in the lower WC levels, but lower in the higher WC levels among the subjects aged 65⁻85 years than subjects aged 40⁻65 years. Even in subjects with normal weight and overweight, increased WC (levels 4, 5, and 6) showed increased HRs for mortality (HRs = 1.156, 1.412, and 1.614 in normal BMI and 1.145, 1.401, and 1.909 in overweight, respectively).

CONCLUSION

There was a linear association between WC and all-cause mortality across all BMI categories even in the subjects with normal or overweight BMI. Physicians should check WC routinely even in the subjects with normal weight or overweight.

Body Mass Index, Waist Circumference, and Mortality in a Large Multiethnic Postmenopausal Cohort-Results from the Women's Health Initiative

OBJECTIVES

To determine whether the relationship between anthropometric measurements of obesity and mortality varies according to age, race, and ethnicity in older women.

DESIGN

Prospective cohort study of multiethnic postmenopausal women.

SETTING

Women's Health Initiative (WHI) observational study and clinical trials in 40 clinics.

PARTICIPANTS

Postmenopausal women aged 50-79 participating in WHI (N = 161,808).

MEASUREMENTS

Baseline height, weight, and waist circumference (WC) were measured, and body mass index (BMI) was calculated based on height and weight. Demographic, health, and lifestyle data from a baseline questionnaire were used as covariates. The outcome was adjudicated death (n = 18,320) during a mean follow-up of 11.4 ± 3.2 years.

RESULTS

Hazard ratios (HRs) and 95% confidence intervals (95% CIs) indicated that ethnicity and age modified (P < .01) the relationship between obesity and mortality. Underweight was associated with higher mortality, but overweight or slight obesity was not a risk factor for mortality in most ethnic groups except for Hispanic women in the obesity I category (HR = 1.42, 95% CI = 1.04-1.95). BMI was not or was only weakly associated with mortality in individuals aged 70-79 (HR = 0.90, 95% CI = 0.85-0.95 for overweight; HR = 0.98, 95 CI = 0.92-1.06 for obese I; HR = 1.11, 95% CI = 1.00-1.23 for obese II; HR = 1.08, 95% CI = 0.92-1.26 for obese III). In contrast, higher central obesity measured using WC was consistently associated with higher mortality in all groups.

CONCLUSION

Underweight is a significant risk factor for mortality in older women, and healthy BMI ranges may need to be specific for age, race, and ethnicity. The findings support a consistent relationship between central obesity and mortality.

The association between A Body Shape Index and mortality: Results from an Australian cohort

It is well recognised that obesity increases the risk of premature death. A Body Shape Index (ABSI) is a formula that uses waist circumference (WC), body mass index (BMI) and height to predict risk of premature mortality, where a high score (Quartile 4) indicates that a person's WC is more than expected given their height and weight. Our study examines the association between ABSI quartiles and all-cause-, cardiovascular- and cancer-related mortality, and primary cause of death. Self-reported demographic and biomedically measured health-related risk factor and weight data was from the baseline stage of the North West Adelaide Health Study (1999-2003, n = 4056), a longitudinal cohort of Australian adults. Death-related information was obtained from the National Death Index. Primary cause of death across ABSI quartiles was examined. The association between mortality and ABSI (quartile and continuous scores) was investigated using a Cox proportional hazards survival model and adjusting for socioeconomic, and self-reported and biomedical risk factors. The proportion of all three types of mortality steadily increased from ABSI Quartile 1 through to Quartile 4. After adjusting for demographic and health-related risk factors, the risk of all-cause mortality was higher for people in ABSI Quartile 4 (HR 2.64, 95% CI 01.56-4.47), and ABSI Quartile 3 (HR 1.95, 95% CI 1.15-3.33), with a moderate association for the continuous ABSI score (HR 1.32, 95% CI 1.18-1.48). ABSI is therefore positively associated with mortality in Australian adults. Different combined measures of obesity such as the ABSI are useful in examining mortality risk.

Cardiovascular and all-cause mortality in relation to various anthropometric measures of obesity in Europeans

BACKGROUND AND AIMS

Cardiovascular and all-cause mortality in relation to various anthropometric measures of obesity is still controversial.

METHODS AND RESULTS

Body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), waist-to-hip ratio (WHR), A Body Shape Index (ABSI) and waist-to-hip-to-height ratio (WHHR) were measured at baseline in a cohort of 46,651 European men and women aged 24-99 years. The relationship between anthropometric measures of obesity and mortality was evaluated by the Cox proportional hazards model with age as a time-scale and with threshold detected by a piecewise regression model. Over a median follow-up of 7.9 years, 2381 men and 1055 women died, 1071 men (45.0%) and 339 women (32.1%) from cardiovascular disease (CVD). BMI had a J-shaped relationship with CVD mortality, whereas anthropometric measures of abdominal obesity had positive linear relationships. BMI, WC and WHtR showed J-shaped associations with all-cause mortality, whereas WHR, ABSI and WHHR demonstrated positive linear relationships. Accordingly, a threshold value was detected at 29.29 and 30.98 kg/m(2) for BMI, 96.4 and 93.3 cm for WC, 0.57 and 0.60 for WHtR, 0.0848 and 0.0813 m(11/6) kg(-2/3) for ABSI with CVD mortality in men and women, respectively; 29.88 and 29.50 kg/m(2) for BMI, 104.3 and 105.6 for WC, 0.61 and 0.67 for WHtR, 0.95 and 0.86 for WHR, 0.0807 and 0.0765 for ABSI in men and women, respectively, and 0.52 for WHHR in women with all-cause mortality.

CONCLUSION

All anthropometric measures of abdominal obesity had positive linear associations with CVD mortality, whereas some showed linear and the others J-shaped relationships with all-cause mortality. BMI had a J-shaped relationship with either CVD or all-cause mortality. Thresholds detected based on mortality may help with clinical definition of obesity in relation to mortality.

Ethnic-specific BMI and waist circumference thresholds

BMI and waist circumference (WC) are used to identify individuals with elevated obesity-related health risks. The current thresholds were derived largely in populations of European origin. This study determined optimal BMI and WC thresholds for the identification of cardiometabolic risk among white and African-American (AA) adults. The sample included 2096 white women, 1789 AA women, 1948 white men, and 643 AA men aged 18-64 years. Elevated cardiometabolic risk was defined as ≥2 risk factors (blood pressure ≥ 130/85 mm Hg; glucose ≥100 mg/dl; triglycerides ≥150 mg/dl; high-density lipoprotein-cholesterol <40 mg/dl (men) or <50 mg/dl (women)). Receiver Operating Characteristic (ROC) curves were used to identify optimal BMI and WC thresholds in each sex-by-ethnicity group. The optimal BMI thresholds were 30 kg/m2 in white women, 32.9 kg/m2 in AA women, 29.1 kg/m2 white men, and 30.4 kg/m2 in AA men, whereas optimal WC thresholds were 91.9 cm in white women, 96.8 cm in AA women, 99.4 in white men, and 99.1 cm in AA men. The sensitivities at the optimal thresholds ranged from 63.5 to 68.5% for BMI and 68.4 to 71.0% for WC and the specificities ranged from 64.2 to 68.8% for BMI and from 68.5 to 71.0% for WC, respectively. In general, the optimal BMI and WC thresholds approximated currently used thresholds in men and in white women. There are no apparent ethnic differences in men; however, in AA women the optimal BMI and WC values are ~3 kg/m2 and 5 cm higher than in white women.

BMI, waist circumference, and mortality according to health status in the older adult population of Spain

Among the explanations proposed for the weak and inconsistent association between BMI and mortality in the elderly are the lack of adjustment for waist circumference (WC) and that the association varies with health status. This work examines the independent association of BMI and WC with mortality in older adults, and the influence of health status on this association. A cohort of 3,536 persons representative of the Spanish population aged >or=60 years was selected in 2000 and 2001, and followed prospectively until 2007. The analyses were performed with Cox models and adjusted for the main confounders. During follow-up, 659 persons died (18.6% of the cohort). Before adjusting for WC, mortality in the upper quartile of BMI was 15% lower than in the lower quartile (hazard ratio (HR): 0.85; 95% confidence interval (CI): 0.66-1.08; P for linear trend = 0.076). After adjusting for WC, the association was even stronger, so that mortality in the upper quartile of BMI was 37% lower than in the lower quartile (HR: 0.63; 95% CI: 0.45-0.88; P for linear trend < 0.003). Before adjusting for BMI, no association was observed between WC and mortality. After adjusting for BMI, WC was positively associated with mortality (HR for upper vs. lower quartile of WC: 1.48; 95% CI: 1.07-2.05; P for linear trend = 0.008). These associations were mainly observed in those with limitations in mobility and agility. BMI has an inverse, and WC has a direct, independent association with mortality in older adults, particularly in those with worse health status.

Waist circumference and waist/hip ratio in relation to all-cause mortality, cancer and sleep apnea

Abdominal obesity assessed by waist or waist/hip ratio are both related to increased risk of all-cause mortality throughout the range of body mass index (BMI). The relative risks (RRs) seem to be relatively stronger in younger than in older adults and in those with relatively low BMI compared with those with high BMI. Absolute risks and risk differences are preferable measures of risk in a public health context but these are rarely presented. There is a great lack of studies in ethnic groups (groups of African and Asian descent particularly). Current cut-points as recommended by the World Health Organization seem appropriate, although it may be that BMI-specific and ethnic-specific waist cut-points may be warranted. Waist alone could replace both waist-hip ratio and BMI as a single risk factor for all-cause mortality. There is much less evidence for waist to replace BMI for cancer risk mainly because of the relative lack of prospective cohort studies on waist and cancer risk. Obesity is also a risk factor for sleep apnoea where neck circumference seems to give the strongest association, and waist-hip ratio is a risk factor especially in severe obstructive sleep apnoea syndrome. The waist circumference and waist-hip ratio seem to be better indicators of all-cause mortality than BMI.

Adiposity and mortality in type 1 diabetes

BACKGROUND

In the general population, adiposity exhibits a J- or U-shaped relationship with mortality; however, in catabolic states this relationship is often inversely linear. We have recently documented an age-independent increase in overweight/obesity in the Pittsburgh Epidemiology of Diabetes Complications Study (EDC) of type 1 diabetes (T1D). As intensified insulin therapy (IIT) may promote weight gain, the impact of weight gain in T1D is of importance. We therefore assessed the association of adiposity with mortality in 655 EDC participants during 20 years of follow-up.

METHODS

Individuals were categorized as underweight (body mass index (BMI)<20), normal (20< or = BMI <25), overweight (25< or = BMI <30), or obese (BMI > or =30). Cox models were constructed using BMI and covariates at baseline, updated means during follow-up, time variation (reflecting most recent status), and change during adulthood as predictors of mortality.

RESULTS

The prevalence of IIT (3+ insulin shots daily and/or pump) increased from 7 to 82%. Overweight increased by 47% and obesity increased sevenfold. There were 146 deaths. In unadjusted models, BMI (modeled continuously) showed a quadratic relationship with mortality (P=0.002, <0.0001 <0.0001 for baseline, updated mean and time-varying models, respectively). However, only in the time-varying model were the obese significantly different from the normal weight, whereas the baseline model showed no differences by BMI category. In both the updated mean and time-varying models, the underweight were at greater risk than were the normal weight (P<0.0001 both models). The nonlinear relationship of adiposity with mortality remained after adjustment for diabetes complications and for biological or socioeconomic/lifestyle risk factors, with the exception of baseline socioeconomic/lifestyle risk factors, in which a linear association emerged. Adjustment for waist circumference eliminated risk in the obese. Finally, weight gain during follow-up was protective.

CONCLUSION

The relationship of adiposity with mortality in T1D now seems to resemble that of the general population, albeit with a marked increased risk in those who are underweight.

Multidisciplinary approach to obesity

Obesity, associated with morbidity and mortality, is a complex disorder, characterised by an increase in fat mass (FM). Most authors agree in considering essential an integrated treatment made up of nutritional intervention, physical reconditioning programme and cognitive-behavioural psychotherapy. However, the feasibility is problematic and data in literature confirming the validity of this approach are poor.

AIM

To verify the efficacy of a multidimensional approach (Nutritional Psycho-Physical Reconditioning - NPPR) in obesity treatment.

METHODS

All patients admitted from June 2002 to June 2004 (464 subjects) ranged from 18 to 65 years old, with a body mass index (BMI) >30 kg/m2 were included in the programme. After the nutritional status evaluation a standard dietetic treatment (group N) or an integrated and multidisciplinary obesity treatment (group NPPR) was proposed.

RESULTS

In group NPPR treatment duration was significantly higher (142.6+/-26 vs 48.6+/-55 days - p=0.000), while the drop-out amount was definitely lower (5.5 vs 54.4%; p=0.000). Weight loss compared to the initial weight and the difference between initial and final FM resulted significantly higher in group NNPR. Subjects in NPPR obtained a higher increase in the distance covered in a 6-minute walk test (59.9+/-19 vs 40.5+/-17 m; p=0.04) and in muscular strength. State and trait anxiety, mood and quality of life scores improved in NPPR subjects while remained substantially stable in group N.

CONCLUSIONS

An integrated approach to obesity is the way to be pursued in order to obtain important and at least short-term results.

General and abdominal adiposity and risk of death in Europe

BACKGROUND

Previous studies have relied predominantly on the body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) to assess the association of adiposity with the risk of death, but few have examined whether the distribution of body fat contributes to the prediction of death.

METHODS

We examined the association of BMI, waist circumference, and waist-to-hip ratio with the risk of death among 359,387 participants from nine countries in the European Prospective Investigation into Cancer and Nutrition (EPIC). We used a Cox regression analysis, with age as the time variable, and stratified the models according to study center and age at recruitment, with further adjustment for educational level, smoking status, alcohol consumption, physical activity, and height.

RESULTS

During a mean follow-up of 9.7 years, 14,723 participants died. The lowest risks of death related to BMI were observed at a BMI of 25.3 for men and 24.3 for women. After adjustment for BMI, waist circumference and waist-to-hip ratio were strongly associated with the risk of death. Relative risks among men and women in the highest quintile of waist circumference were 2.05 (95% confidence interval [CI], 1.80 to 2.33) and 1.78 (95% CI, 1.56 to 2.04), respectively, and in the highest quintile of waist-to-hip ratio, the relative risks were 1.68 (95% CI, 1.53 to 1.84) and 1.51 (95% CI, 1.37 to 1.66), respectively. BMI remained significantly associated with the risk of death in models that included waist circumference or waist-to-hip ratio (P<0.001).

CONCLUSIONS

These data suggest that both general adiposity and abdominal adiposity are associated with the risk of death and support the use of waist circumference or waist-to-hip ratio in addition to BMI in assessing the risk of death.

Does the relationship between waist circumference, morbidity and mortality depend on measurement protocol for waist circumference?

There is currently no consensus regarding the optimal protocol for measurement of waist circumference (WC), and no scientific rationale is provided for any of the WC protocols recommended by leading health authorities. A panel of experts conducted a systematic review of 120 studies (236 samples) to determine whether measurement protocol influenced the relationship of WC with morbidity of cardiovascular disease (CVD) and diabetes and with mortality from all causes and from CVD. Statistically significant associations with WC were reported for 65% (152) of the samples across all outcomes combined. Common WC protocols performed measurement at the minimal waist (33%), midpoint (26%) and umbilicus (27%). Non-significant associations were reported for 27% (64) of the samples. Most of these protocols measured WC at the midpoint (36%), umbilicus (28%) or minimal waist (25%). Significant associations were observed for 17 of the remaining 20 samples, but these were not significant when adjustment was made for covariates. For these samples, the most common WC protocols were the midpoint (35%) and umbilicus (30%). Similar patterns of association between the outcomes and all WC protocols were observed across sample size, sex, age, race and ethnicity. Our findings suggest that WC measurement protocol has no substantial influence on the association between WC, all-cause and CVD mortality, CVD and diabetes.

Concurrent and separate effects of body mass index and waist-to-hip ratio on 24-year mortality in the Population Study of Women in Gothenburg: Evidence of age-dependency

Obesity is generally assumed to be an important risk factor for death and morbidity. However, the association between excess body weight and all-cause mortality among younger and older women and the impact of body mass index (BMI) and waist-to-hip ratio (WHR) concurrently is not fully understood. In 1968-1969 we initiated a prospective study comprising a population sample of 1,462 women from Gothenburg, Sweden. During a 24 year period, until 1992-1993, 265 women had died. A multivariable Cox Proportional Hazards Regression model was used to estimate the relative risk of death in relation to BMI and WHR, with age and other covariates of age-specific interest as smoking, physical activity at work and leisure time and serum triglyceride concentration, at start of the study. BMI and WHR were analyzed as independent variables. Younger women (38 and 46 years at baseline) presented a statistically significant non-linear (U-shaped) relation between BMI and mortality. Among older women (50, 54 and 60 years at baseline), a significant negative linear relationship with decreasing mortality in relation to increasing BMI values was seen. For all women a higher WHR was related to an increased risk of death. The lowest risk of death among younger women corresponded to a low WHR and a BMI within the middle range. For older women the highest survival was observed for those with lowest WHR and highest BMI. Thus, in older women a high BMI seems not to be an increased risk as long as adiposity is not centrally located.

Body mass index is inversely related to mortality in older people after adjustment for waist circumference

OBJECTIVES

To examine the individual and combined influence of body mass index (BMI) and waist circumference (WC) on mortality risk in older people.

DESIGN

Longitudinal cohort study.

SETTING

Cardiovascular Health Study, a longitudinal study of cardiovascular disease and its risk factors in older people.

PARTICIPANTS

Five thousand two hundred men and women aged 65 and older.

MEASUREMENTS

BMI and WC were measured at baseline. The risks of all-cause mortality associated with BMI and WC were examined using Cox proportional hazards models over 9 years of follow-up.

RESULTS

When examined individually, BMI and WC were both negative predictors of mortality, but when BMI and WC were examined simultaneously, BMI was a negative predictor of mortality, whereas WC was a positive predictor of mortality. After controlling for WC, mortality risk decreased 21% for every standard deviation increase in BMI. After controlling for BMI, mortality risk increased 13% for every standard deviation increase in WC. The patterns of associations were consistent by sex, age, and disease status.

CONCLUSION

Higher BMI values indicated a lower mortality risk once the risk attributable to WC was accounted for, whereas higher WC values indicate a higher mortality risk once the risk attributable to BMI was accounted for. Both BMI and WC should be measured in the clinical setting, but in older adults higher BMI is associated with lower mortality rates.

Weight change in adult life and health outcomes

OBJECTIVE

To investigate the relationship between weight change in adult life and subsequent mortality and cancer incidence in women.

RESEARCH METHODS AND PROCEDURES

In 1994 to 1995, all women (age range, 42 to 81) still under general practitioner observation in the United Kingdom's Royal College of General Practitioners Oral Contraception Study (n = 12,303) were sent a health survey asking about health and lifestyle issues, including current weight and weight at age 30. The main outcome measures were 6-year all-cause mortality and cancer incidence among different weight change deciles. Cox regression was used to calculate hazard ratios that were adjusted for: social class at recruitment, BMI at age 30, and age group, parity, smoking status, and hormone replacement therapy status in 1995.

RESULTS

Women who had been obese at age 30 were more likely to die and significantly more likely to develop cancer in the 6 years after the health survey than non-obese respondents. Women reporting weight gains between age 30 and 1995 were significantly less likely to die during the 6 years after the health survey than those with a stable weight, whereas those with weight loss did not fare any better than those in the stable-weight group.

DISCUSSION

Although obesity at young age was associated with subsequent mortality and cancer incidence, weight gain over a time period of 12 to 51 years appeared to be beneficial when compared with women with stable weight over the same time period. Further research is needed to confirm or refute our findings and to allow detailed examination of potential explanations for them.

Fitness alters the associations of BMI and waist circumference with total and abdominal fat

OBJECTIVE

We tested the following hypotheses in black and white men and women: 1) for a given BMI or waist circumference (WC), individuals with moderate cardiorespiratory fitness (CRF) have lower amounts of total fat mass and abdominal subcutaneous and visceral fat compared with individuals with low CRF; and 2) exercise training is associated with significant reductions in total adiposity and abdominal fat independent of changes in BMI or WC.

RESEARCH METHODS AND PROCEDURES

The sample included 366 sedentary male (111 blacks and 255 whites) and 462 sedentary female (203 blacks and 259 whites) participants in the HERITAGE Family Study. The relationships between BMI and WC with total fat mass (determined by underwater weighing) and abdominal subcutaneous and visceral fat (determined by computed tomography) were compared in subjects with low (lower 50%) and moderate (upper 50%) CRF. The effects of a 20-week aerobic exercise training program on changes in these adiposity variables were examined in 86% of the subjects.

RESULTS

Individuals with moderate CRF had lower levels of total fat mass and abdominal subcutaneous and visceral fat than individuals with low CRF for a given BMI or WC value. The 20-week aerobic exercise program was associated with significant reductions in total adiposity and abdominal fat, even after controlling for reductions in BMI and WC. With few exceptions, these observations were true for both men and women and blacks and whites.

DISCUSSION

These findings suggest that a reduction in total adiposity and abdominal fat may be a means by which CRF attenuates the health risk attributable to obesity as determined by BMI and WC.

Physical inactivity, excess adiposity and premature mortality

The purpose of this report is to review the evidence that physical inactivity and excess adiposity are related to an increased risk of all-cause mortality, and to better identify the independent contributions of each to all-cause mortality rates. A variance-based method of meta-analysis was used to summarize the relationships from available studies. The summary relative risk of all-cause mortality for physical activity from the 55 analyses (31 studies) that included an index of adiposity as a covariate was 0.80 [95% confidence interval (CI) 0.78-0.821, whereas it was 0.82 [95% CI 0.80-0.84] for the 44 analyses (26 studies) that did not include an index of adiposity. Thus, physically active individuals have a lower risk of mortality by comparison to physically inactive peers, independent of level of adiposity. The summary relative risk of all-cause mortality for an elevated body mass index (BMI) from the 25 analyses (13 studies) that included physical activity as a covariate was 1.23 [95% CI 1.18-1.29], and it was 1.24 [95% CI 1.21-1.28] for the 81 analyses (36 studies) that did not include physical activity as a covariate. Studies that used a measure of adiposity other than the BMI show similar relationships with mortality, and stratified analyses indicate that both physical inactivity and adiposity are important determinants of mortality risk.

Waist circumference, BMI, smoking, and mortality in middle-aged men and women

OBJECTIVE

Measurement of waist circumference alone as a proxy of abdominal fat mass has been suggested as a simple clinical alternative to BMI for detecting adults with possible health risks due to obesity.

RESEARCH METHODS AND PROCEDURES

From 1993 to 1997, 27,178 men and 29,875 women, born in Denmark, 50 to 64 years of age, were recruited in the Danish prospective study Diet, Cancer and Health. By the end of the year 2000, 1465 deaths had occurred. We evaluated the relationship between waist circumference and BMI (simultaneously included in the model) and all-cause mortality. We used Cox regression models to estimate the mortality-rate ratios and to consider possible confounding from smoking.

RESULTS

Waist circumference among both men and women showed a strong dose-response type of relationship with mortality when adjusted for BMI, whereas the low range of BMI was inversely associated with mortality when adjusted for waist circumference. A 10% larger waist circumference corresponded to a 1.48 (95% confidence interval: 1.36 to 1.61) times higher mortality over the whole range of waist circumference. The associations were independent of age and time since baseline examination. Restriction to never smokers showed a similar pattern, but a weakening of the associations.

DISCUSSION

Despite the high correlation between waist circumference and BMI, the combination may be very relevant in clinical practice because waist circumference for given BMI was a strong predictor of all-cause mortality. The inverse association between BMI and mortality for given waist circumference was diminished in never smokers, particularly for high values of BMI.