Obesity and 10-year mortality in very old African Americans and Yoruba-Nigerians: exploring the obesity paradox

The Obesity Paradox and Mortality in Older Adults: A Systematic Review

“Obesity paradox” describes the counterintuitive finding that aged overweight and obese people with a particular disease may have better outcomes than their normal weight or underweight counterparts. This systematic review was performed to summarize the publications related to the obesity paradox in older adults, to gain an in-depth understanding of this phenomenon. PubMed©, Embase©, and Scopus© were used to perform literature search for all publications up to 20 March 2022. Studies were included if they reported data from older adults on the relation between BMI and mortality. The following article types were excluded from the study: reviews, editorials, correspondence, and case reports and case series. Publication year, study setting, medical condition, study design, sample size, age, and outcome(s) were extracted. This review has been registered with PROSPERO (no. CRD42021289015). Overall, 2226 studies were identified, of which 58 were included in this systematic review. In all, 20 of the 58 studies included in this review did not find any evidence of an obesity paradox. Of these 20 studies, 16 involved patients with no specific medical condition, 1 involved patients with chronic diseases, and 2 involved patients with type 2 diabetes mellitus. Seven out of the nine studies that looked at short-term mortality found evidence of the obesity paradox. Of the 28 studies that examined longer-term mortality, 15 found evidence of the obesity paradox. In the studies that were conducted in people with a particular medical condition (n = 24), the obesity paradox appeared in 18 cases. Our work supports the existence of an obesity paradox, especially when comorbidities or acute medical problems are present. These findings should help guide strategies for nutritional counselling in older populations.

Nutritional status and associated factors among community-dwelling elderly

BACKGROUND AND AIMS

Although the ageing of the Cameroonian population is a public health issue in the coming years, the nutritional status of the elderly is unknown. The aim of the study was to assess the nutritional status, health status and associated socio-demographic factors among elderly in Cameroon.

METHODS

A cross-sectional study of 599 elderly (aged ≥ 60) was conducted in urban and rural areas. Several socio-demographic, sanitary, and anthropometric (weight, height, body mass index (BMI), Waist Circumference (WC), Mid-Upper Arm Circumference (MUAC)) data were collected. Nutritional status was defined according to WHO. Multinomial analysis was performed to identify factors associated with nutritional status. The threshold of statistical significance was 5%.

RESULTS

The population, representative of the elderly, was aged 68.9 ± 7.2 years, with sex ratio M/F = 0.93, weight 68.5 ± 14.7 kg, BMI 24.7 ± 5.3, WC 90.1 ± 12.8 cm and MUAC 28.2 ± 5.0 cm. According to BMI, undernutrition was 19.7%, normal status 37.9%, overweight 24.9%, obesity 17.5%. The concordance for undernutrition between BMI and MUAC was weak (kappa = 0.3). In multinomial analysis, only no medication was negatively associated with undernutrition (OR = 0.3). Obesity was positively associated with the urban environment (OR = 4.8) and inactivity (OR = 2.9) and negatively associated with male gender (OR = 0.4), widowed (OR = 0.2), head of household (OR = 0.4), no income (OR = 0.3), one pathology (OR = 0.4), no medication (OR = 0.2), having normal diastolic pressure (OR = 0.2).

CONCLUSIONS

Undernutrition and obesity (more frequent in women, and in urban area) affect 37.2% of the elderly. These nutritional disorders are a public health problem that cannot be ignored.

Recent Consanguinity and Outbred Autozygosity Are Associated With Increased Risk of Late-Onset Alzheimer's Disease

Prior work in late-onset Alzheimer's disease (LOAD) has resulted in discrepant findings as to whether recent consanguinity and outbred autozygosity are associated with LOAD risk. In the current study, we tested the association between consanguinity and outbred autozygosity with LOAD in the largest such analysis to date, in which 20 LOAD GWAS datasets were retrieved through public databases. Our analyses were restricted to eight distinct ethnic groups: African-Caribbean, Ashkenazi-Jewish European, European-Caribbean, French-Canadian, Finnish European, North-Western European, South-Eastern European, and Yoruba African for a total of 21,492 unrelated subjects (11,196 LOAD and 10,296 controls). Recent consanguinity determination was performed using FSuite v1.0.3, according to subjects' ancestral background. The level of autozygosity in the outbred population was assessed by calculating inbreeding estimates based on the proportion (FROH) and the number (NROH) of runs of homozygosity (ROHs). We analyzed all eight ethnic groups using a fixed-effect meta-analysis, which showed a significant association of recent consanguinity with LOAD (N = 21,481; OR = 1.262, P = 3.6 × 10-4), independently of APOE ∗4 (N = 21,468, OR = 1.237, P = 0.002), and years of education (N = 9,257; OR = 1.274, P = 0.020). Autozygosity in the outbred population was also associated with an increased risk of LOAD, both for F ROH (N = 20,237; OR = 1.204, P = 0.030) and N ROH metrics (N = 20,237; OR = 1.019, P = 0.006), independently of APOE ∗4 [(F ROH, N = 20,225; OR = 1.222, P = 0.029) (N ROH, N = 20,225; OR = 1.019, P = 0.007)]. By leveraging the Alzheimer's Disease Sequencing Project (ADSP) whole-exome sequencing (WES) data, we determined that LOAD subjects do not show an enrichment of rare, risk-enhancing minor homozygote variants compared to the control population. A two-stage recessive GWAS using ADSP data from 201 consanguineous subjects in the discovery phase followed by validation in 10,469 subjects led to the identification of RPH3AL p.A303V (rs117190076) as a rare minor homozygote variant increasing the risk of LOAD [discovery: Genotype Relative Risk (GRR) = 46, P = 2.16 × 10-6; validation: GRR = 1.9, P = 8.0 × 10-4]. These results confirm that recent consanguinity and autozygosity in the outbred population increase risk for LOAD. Subsequent work, with increased samples sizes of consanguineous subjects, should accelerate the discovery of non-additive genetic effects in LOAD.

Adherence to a healthy lifestyle counteracts the negative effects of risk factors on all-cause mortality in the oldest-old

In the study, we examined the extent to which the harmful effects of risk factors on all-cause mortality can be counteracted by healthy lifestyle practices in the oldest-old (80 years of age and older). A total of 17,660 oldest-old from China were followed up for up to 10 years. The data were analyzed using the Cox proportional hazard model with adjustment for potential confounders. We found that having a rural residence, not being married, having lower economic status, physical disability, impaired cognitive function, or comorbidity were all associated with an elevated risk of mortality. Using these factors, we computed a weighted "risk score." Because never smoking, never drinking, doing physical exercise, having an ideal diet, and a normal weight were independently associated with lower mortality, we also combined them to compute a weighted "protection score." Both scores were divided into lowest, middle, and highest groups using their tertiles. In joint effect analyses, participants with the combined highest-risk score and lowest-protection score profile had a nearly threefold higher joint death risk. These analyses show that adherence to a healthy lifestyle counteracts the negative effect of risk factors on all-cause mortality in the oldest-old by more than 20%.

Obesity Paradox in Aging: From Prevalence to Pathophysiology

Recent advances in medical technology and health care have greatly improved the management for chronic diseases and prolonged human lifespan. Unfortunately, increased lifespan and the aging population impose a major challenge on the ever-rising prevalence of chronic diseases, in particular cardiometabolic stress associated with the pandemic obesity in our modern society. Although overweight and obesity are associated with incident cardiovascular diseases (CVD), including heart failure (HF), it paradoxically leads to a more favorable prognosis in patients with chronic HF, a phenomenon commonly defined as "obesity paradox". Numerous population-based and clinical studies have suggested possible explanations such as better metabolic reserve, smoking and disease-associated weight loss for obesity paradox. Recent evidence noticed a shift in obesity paradox with aging. While some studies have reported a more pronounced "obesity paradox" in the older patients, others have seen diminished cardiac benefits with overweight and obesity in the elderly patients with CVD. These findings suggested that a complex relationship among aging, metabolism, and HF severity/chronicity, which may explain the shift in obesity paradox in the elderly. Aging negatively affects body metabolism and cardiac function although its precise impact on obesity paradox remains elusive. To develop new strategies for cardiovascular health in the elderly, it is imperative to understand the precise role for aging on obesity-related CVD.

BMI, Waist Circumference and All-Cause Mortality in a Middle-Aged and Elderly Chinese Population

OBJECTIVE

To investigate the association of obesity and all-cause mortality in a sample of middle-aged and elderly population.

DESIGN AND SETTING

Information of participants was collected in the Dongfeng-Tongji study, a perspective cohort study of Chinese occupational population. The main outcome was risk of death after 8.5 years of follow-up.

PARTICIPANTS AND MEASUREMENTS

We examined the association of BMI, waist circumference (WC, and waist-height ratio (WHtR) with all-cause mortality in the Dongfeng-Tongji cohort study (n=26,143). Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CI) for all-cause mortality. Area under the receiver operating characteristic curves and net reclassification improvement (NRI) were used to calculate the power of prediction models.

RESULTS

During a mean of 8.5 years of follow-up, 2,246 deaths were identified. There is a U-shaped association of BMI with all-cause mortality in the middle-aged and elderly Chinese population. Compared with individuals with normal BMI, underweight was positively (HR=2.16, 95% CI: 1.73, 2.69) while overweight (HR=0.75, 95% CI: 0.67, 0.84) and obesity (HR=0.67, 95% CI: 0.56, 0.79) were negatively associated with all-cause mortality after adjustment for potential confounders including WC. In contrast, WC (Q5 vs. Q1, HR=1.55, 95% CI: 1.29, 1.86) and WHtR (Q5 vs.Q1, HR=1.69, 95% CI: 1.40, 2.04) were positively associated with mortality after further adjustment for BMI (P trend < 0.001). Addition of both BMI and WC into the all-cause mortality predictive model significantly increased AUC (P =0.0002) and NRI (NRI = 2.57%, P = 0.0007).

CONCLUSIONS

BMI and WC/WHtR were independently associated with all-cause mortality after mutual adjustment. Combination of BMI and WC/WHtR improved the predictive ability of all-cause mortality risk in the middle-aged and elderly population.

Undernutrition and obesity among elderly people living in two cities of developing countries: Prevalence and associated factors in the EDAC study

BACKGROUND

Nutritional status among elderly people living in Sub-Saharan Africa is poorly studied, even though undernutrition and obesity are known to cause many complications and are risk factors for progression and death in several diseases. The aims of this study were to assess the nutritional status of the elderly in Central Africa and to study the factors associated with nutritional disorders (undernutrition and obesity).

METHODS

Two cross-sectional population-based studies were carried out in the capitals of Central African Republic (CAR) and Republic of Congo (ROC) between 2008 and 2009. Participants were aged ≥65 years old and underwent nutritional assessment including the following measurements: weight, height, body mass index (BMI), waist circumference (WC). Diet was also investigated. Nutritional status was defined according to the WHO BMI classification (<18.5 = undernutrition; ≥30 = obesity). Multinomial regression analysis was performed in order to identify factors associated with nutritional status.

RESULTS

990 elderly people underwent nutritional assessment (482 in CAR and 508 in ROC). Mean BMI was 22.7 ± 4.8 kg/m². The prevalence of undernutrition was 19.2% and was lower in ROC than in CAR (9.5% vs. 29.5%; p < 0.0001). The prevalence of obesity was 8.8% and was higher in ROC than in CAR (14.6% vs. 2.7%; p < 0.0001). The mean WC was 85.3 ± 28.4 cm. Adjusted on study site, increasing age (OR = 1.6 [95% CI: 1.1-2.3] for 75-84 years, OR = 2.6 [95% CI: 1.4-4.8] for 85+ years), occupation as farmer/breeder (OR = 2.2 [95% CI: 1.1-4.2]), smoking (OR = 1.71 [95% CI: 1.14-2.56]) and low sugar consumption (OR = 1.7 [95% CI: 1.1-2.7]) were positively associated with undernutrition whereas only female sex was positively associated with obesity (OR = 5.0 [95% CI: 2.2-11.0]).

CONCLUSIONS

The prevalence of undernutrition is high in the elderly population of these countries, in contrast to obesity. Undernutrition and obesity are associated with different socio-economic factors and food consumption. Simple nutritional advice could contribute to improving the nutritional status of elderly people in Central Africa.

Interethnic Differences in Serum Lipids and Implications for Cardiometabolic Disease Risk in African Ancestry Populations

African Americans generally have a healthier lipid profile (lower triglycerides and higher high-density lipoprotein cholesterol concentration) compared with those of other ethnicities. Paradoxically, African Americans do not experience a decreased risk of the cardiometabolic diseases that serum lipids are expected to predict. This review explores this mismatch between biomarker and disease among African ancestry individuals by investigating the presence of interethnic differences in the biological relationships underlying the serum lipids-disease association. This review also discusses the physiologic and genomic factors underlying these interethnic differences. Additionally, because of the importance of serum lipids in assessing disease risk, interethnic differences in serum lipids have implications for identifying African ancestry individuals at risk of cardiometabolic disease. Where possible, data from Africa is included, to further elucidate these ancestral differences in the context of a different environmental background.

Does Body Mass Index Modify Memory, Reasoning, and Speed of Processing Training Effects in Older Adults

OBJECTIVE

To describe 10-year trajectories of cognitive performance by body mass index (BMI) class and to investigate BMI differences in response to memory, reasoning, and speed of processing training in older adults.

METHODS

This is a secondary analysis of the multisite, randomized trial Advanced Cognitive Training for Independent and Vital Elderly. There were 701 older adults with normal weight, 1,081 with overweight, and 902 with obesity (mean age 73.6) randomized to memory training, reasoning training, speed of processing training, or no-training control group. Participants completed memory, reasoning, and speed of processing tests. Baseline sociodemographic, health, and chronic disease measures were included as covariates in analyses.

RESULTS

The 10-year trajectories of memory, reasoning, or speed of processing performance did not differ by BMI status among the participants randomized to the untrained control arm. The training effect on the reasoning and speed of processing outcomes did not differ by BMI status. The training effect on the memory outcome in participants with a BMI indicating obesity, however, was just 38% of that observed in participants with normal-weight BMI.

CONCLUSIONS

These analyses of data from the largest trial of cognitive training ever conducted suggest that older adults with obesity may be less responsive to memory training.

BMI and all cause mortality: systematic review and non-linear dose-response meta-analysis of 230 cohort studies with 3.74 million deaths among 30.3 million participants

OBJECTIVE

To conduct a systematic review and meta-analysis of cohort studies of body mass index (BMI) and the risk of all cause mortality, and to clarify the shape and the nadir of the dose-response curve, and the influence on the results of confounding from smoking, weight loss associated with disease, and preclinical disease.

DATA SOURCES

PubMed and Embase databases searched up to 23 September 2015.

STUDY SELECTION

Cohort studies that reported adjusted risk estimates for at least three categories of BMI in relation to all cause mortality.

DATA SYNTHESIS

Summary relative risks were calculated with random effects models. Non-linear associations were explored with fractional polynomial models.

RESULTS

230 cohort studies (207 publications) were included. The analysis of never smokers included 53 cohort studies (44 risk estimates) with >738 144 deaths and >9 976 077 participants. The analysis of all participants included 228 cohort studies (198 risk estimates) with >3 744 722 deaths among 30 233 329 participants. The summary relative risk for a 5 unit increment in BMI was 1.18 (95% confidence interval 1.15 to 1.21; I(2)=95%, n=44) among never smokers, 1.21 (1.18 to 1.25; I(2)=93%, n=25) among healthy never smokers, 1.27 (1.21 to 1.33; I(2)=89%, n=11) among healthy never smokers with exclusion of early follow-up, and 1.05 (1.04 to 1.07; I(2)=97%, n=198) among all participants. There was a J shaped dose-response relation in never smokers (Pnon-linearity <0.001), and the lowest risk was observed at BMI 23-24 in never smokers, 22-23 in healthy never smokers, and 20-22 in studies of never smokers with ≥20 years' follow-up. In contrast there was a U shaped association between BMI and mortality in analyses with a greater potential for bias including all participants, current, former, or ever smokers, and in studies with a short duration of follow-up (<5 years or <10 years), or with moderate study quality scores.

CONCLUSION

Overweight and obesity is associated with increased risk of all cause mortality and the nadir of the curve was observed at BMI 23-24 among never smokers, 22-23 among healthy never smokers, and 20-22 with longer durations of follow-up. The increased risk of mortality observed in underweight people could at least partly be caused by residual confounding from prediagnostic disease. Lack of exclusion of ever smokers, people with prevalent and preclinical disease, and early follow-up could bias the results towards a more U shaped association.

Sex and Race Differences in the Relationship between Obesity and C-Reactive Protein

C-reactive protein (CRP) is a risk factor for cardiovascular disease and mortality; it is known to be positively associated with obesity but there is some evidence that this association differs by race or sex. We used nationally representative data of adults aged >50 years to investigate sex and race modifiers of the associations between obesity and CRP in non-Hispanic White males (n=3,517) and females (n=4,658), and non-Hispanic Black males (n=464) and females (n=826). Using multiple linear regression models with the natural logarithm of CRP as the dependent variable, we sequentially included body mass index (BMI), a body shape index (ABSI), and socioeconomic, health and health behavior covariates in the model. The association between BMI and CRP was significantly stronger in females than males. Obese White females had mean CRP values slightly above 3 mg/liter (vs 2 for White males) and Black females had mean CRP values >4 mg/liter (vs 3 for Black males). More than 50% of Black females in the United States have obesity. Continued research into racial and sex differences in the relationship between obesity, inflammation, and health risks may ultimately lead to more personalized weight loss recommendations.

Body composition phenotypes and obesity paradox

PURPOSE OF REVIEW

The obesity paradox is a highly controversial concept that may be attributed to methodological limitations related to its identification. One of the primary concerns is the use of BMI to define obesity. This index does not differentiate lean versus adipose tissue compartments (i.e. body composition) confounding health consequences for morbidity and mortality, especially in clinical populations. This review will describe the past year's evidence on the obesity paradox phenomenon, primarily focusing on the role of abnormal body composition phenotypes in explaining the controversies observed in the literature.

RECENT FINDINGS

In spite of the substantial number of articles investigating the obesity paradox phenomenon, less than 10% used a direct measure of body composition and when included, it was not fully explored (only adipose tissue compartment evaluated). When lean tissue or muscle mass is taken into account, the general finding is that a high BMI has no protective effect in the presence of low muscle mass and that it is the latter that associates with poor prognosis.

SUMMARY

In view of the body composition variability of patients with identical BMI, it is unreasonable to rely solely on this index to identify obesity. The consequences of a potential insubstantial obesity paradox are mixed messages related to patient-related prognostication.

Age Differences in the Association Between Body Mass Index Class and Annualized Medicare Expenditures

OBJECTIVE

The aim of the study is to assess the relationship between body mass index (BMI) class and Medicare claims among young-old (65-69), old (70-74), and old-old (75+) adults over a 10-year period.

METHOD

We assessed costs by BMI class and age group among 9,300 respondents to the 1998 Health and Retirement Study (HRS) with linked 1998-2008 Medicare claims data. BMI was classified as normal (18.5-24.9), overweight (25-29.9), mild obesity (30-34.9), or severe obesity (35 or above).

RESULTS

Annualized total Medicare claims adjusted for age, gender, ethnicity, education, and smoking history were 109% greater for severely obese young-old adults in comparison with normal weight young-old adults (US$9,751 vs. US$4,663). Total annualized claim differences between the normal weight and severely obese in the old and old-old groups were not statistically significant.

DISCUSSION

Excess Medicare expenditures related to obesity may be concentrated among severely obese young-old adults. Preventing severe obesity among middle and older aged adults may have large cost implications for society.

Effects of body mass index, abdominal obesity, and type 2 diabetes on mortality in community-dwelling elderly in Sao Paulo, Brazil: analysis of prospective data from the SABE study

BACKGROUND

The majority of studies on the effects of adiposity on mortality in the elderly have been conducted in developed countries with mixed results. We investigated the association between adiposity and mortality in a cohort of community-dwelling elderly in Sao Paulo, Brazil.

METHODS

Body mass index (BMI), waist circumference, waist-to-hip ratio, and type 2 diabetes were evaluated in 1,882 participants (mean age 71.0 ± 8.3 years old, 61% female). Mortality was confirmed by national vital statistics records during a maximum of 10 years of follow-up. Proportional hazards models were used to estimate hazard ratios (HRs) for mortality after adjusting for sociodemographics and comorbidities. In a subsample of 897 participants, the effects of changes in measures of adiposity on mortality were investigated during a median follow-up of 4.6 years.

RESULTS

Having type-2 diabetes at baseline was associated with increased mortality (HR = 1.44, 95% CI: 1.17-1.77), with a higher HR among men. When compared with normal weight participants (BMI = 20-<25kg/m(2)), overweight and obesity were not associated with mortality (overweight: HR = 0.84 [0.70, 1.02]; obesity: HR = 0.82 [0.64, 1.06]), whereas participants with low-normal weight (BMI = 18.5<20 kg/m(2)) had increased risk of death (HR = 1.51 [1.08-2.10]). Higher waist circumference and waist-to-hip ratio were not associated with increased mortality. Weight gain was protective against mortality in all BMI categories, except in obese participants, and weight loss increased the risk of death in all BMI categories by 42-63%.

CONCLUSIONS

In community-dwelling elderly in Sao Paulo, overweight and obesity were not associated with a higher risk of death, and weight gain seemed to reduce mortality, except in the obese.