Impact of overweight and obesity on medical care costs, all-cause mortality, and the risk of cancer in Japan

Estimating Burden of Mortality due to Excess Body Mass Index in the US Adult Population by Combining Evidence from a Mendelian Randomization Study and National Health Surveys

Importance

Assessment of the burden of mortality due to excess body weight in a population and its subgroups is important for designing health policies for interventions. Mendelian randomization (MR) studies can provide an opportunity to correct for unmeasured confounding bias present in observational studies, but such evidence has not been used to assess population burden of mortality due to excess BMI.

Objective

Combine results from a recent Mendelian randomization (MR) study and data from the National Health Surveys to estimate preventable fraction (PF) of 10-year all-cause and cause-specific mortality by different degrees of BMI reduction in the US adult population and underlying risk strata.

Designs

We use cross-sectional data on the distribution of BMI and other risk factors of mortality from the National Health and Nutritional Examination Surveys (NHANES) across two-time spans (1999-2006 and 2017-2018). We use linked data from National Death Index to characterize the observed risk of 10-year mortality associated with BMI and other risk factors based on the NHANES 1999-2006 cohort. We further import results from an external MR study on linear and non-linear effects of BMI and use novel methods to estimate preventable fraction (PF) for deaths under different counterfactual scenarios of BMI reduction in the NHANES population.

Settings

Primary analysis is restricted to the NHANES non-Hispanic white population (age range 40-69 years) due to the unavailability of MR studies in other groups, but projections are provided for the African American population under the assumption of homogeneity of causal effects.

Outcome

Preventable fraction for 10-year all-cause mortality and cause-specific mortality due to 50% and 100% reduction of excess BMI (BMI>25.6 kg/m2) for the US adult population in the age range of 40-69 years.

Results

Nearly 33% and 43% of the NHANES 2017-2018 target population are overweight (25.6 kg/m2≤BMI<30.7 kg/m2) and obese (BMI>30.7 kg/m2), respectively, according to WHO definitions. Estimates of relative risks for different BMI categories (relative to normal BMI) from the external MR study range from 1.05 (25.6 kg/m2 ≤ BMI < 27.8 kg/m2) to 5.95 (BMI> 42.4 kg/m2). We estimate PF for 10-year all-cause mortality due to 50% and 100% reduction of excess BMI for the population to be 24% (95% CI: 14 - 34) and 35% (95% CI: 22-48), respectively. The estimate of PF of death due to heart disease and cancer for this population reaches up to 48% (95% CI: 25-71) and 18% (95% CI: -2-38), respectively. Partitioning of PF shows that 60% of all BMI-attributable deaths arise from only 12% of the population who are at the highest risk due to obesity and a combination of other risk factors.

Conclusions

Nearly one in three deaths in a contemporary US adult population can be attributed to overweight and obesity. A substantial fraction of these deaths are likely to be preventable through pragmatic and targeted BMI interventions.

Increased Body Fat and Organic Acid Anions Production Are Associated with Larger Kidney Size in ADPKD

Background and Objectives: A high body mass index (BMI) is associated with the progression of autosomal dominant polycystic kidney disease (ADPKD). However, body fat (BF), which is another adiposity marker, has not yet been studied. Excessive weight may promote elevation in the endogenous synthesis of organic acid (OA) anions. Accordingly, we aimed to investigate the possible association of the aforementioned markers with kidney volume and renal function in patients with ADPKD. Materials and Methods: We conducted a retrospective cohort study of adult ADPKD outpatients involving clinical, serum, and urinary laboratorial data and body composition assessments retrieved from their medical records. BF was estimated by skinfold thickness (mm) on the non-dominant arm and was considered as normal or high for each sex. Total kidney volume (TKV) and height-adjusted volume (htTKV) were measured by magnetic resonance imaging. The annual estimated glomerular filtration rate (eGFR) slope was analyzed during a median follow-up time of 6 (5.0-7.0) years to calculate rapid progression (decline in renal function ≥2.5 mL/min/year over 5 years). Results: A total of 104 patients were included (41.9 ± 11.9 years old, 38.5% men), with 62.5% of the patients classified as high BF. The High BF group presented higher levels of OA, glycosylated hemoglobin (HbA1c), C-reactive protein (CRP), 24 h urinary sodium (UNa), and htTKV, and lower eGFR than those with a normal BF. In the multivariate linear regression, the associated variables with TKV were high BF, OA and BMI (std. β 0.47, p < 0.05; std. β 0.36, p = 0.001; std. β 0.25, p = 0.01, respectively). In the binary logistic regression, when adjusted for potential confounders, UNa was the only parameter associated with an increased risk of eGFR decline ≥2.5 mL/min/year (OR 1.02, 95% CI 1.01-1.03, p = 0.02). Conclusions: Increased body fat and endogenous production of organic acid anions are associated with larger kidney size in ADPKD but not with a decline in renal function.

Does the body mass index influence the long-term survival of unicompartmental knee prostheses? A retrospective multi-centre study

PURPOSE

The effect of being obese on the long-term survival of total joint arthroplasty is persistently discussed. Considering only studies with large cohort of patients and meta-analysis, a high body mass index has been correlated with a higher incidence of complication but not univocally with a lower survival rate. In this study, we analyzed, retrospectively, the data of patients that received unicompartmental knee prostheses in order to examine if obesity has an effect on clinical outcomes.

METHODS

A retrospective multi-centre study was carried out on 4964 unicompartmental knee replacements between July 2000 and December 2016, the patients involved were 3976, with 988 bilateral cases. The patients were categorized into three groups: non-obese with a body mass index (BMI) < 30 kg/m², obese with BMI ranged between 30 and 39 kg/m², and morbidly obese (BMI ≥ 40 kg/m²). The outcome was measured using the Cox proportional hazards model with end point UKA revision for any reasons. Results were stratified for sex, age, weight, and bi-laterality.

RESULTS

The morbidly obese group was significantly younger and required a significantly longer operating time. No statistical significant differences were observed considering the BMI groups in terms of type of insert, type of tibial component, prosthetic condyle, and prosthesis fixation (p > 0.05; chi-square test).

CONCLUSIONS

Obese and morbidly obese patients have as much to gain from total knee replacement as non-obese patients.

Discrepancies between subjective perception and waist-to-height ratio measurement of obesity, and their policy implications

In social sciences, researchers rely on subjective perceptions of obesity measures to examine the determinants of obesity and the likely effects of obesity on health outcomes. However, subjective perception tends to produce estimation biases. In this study, we investigated the misreporting behavior of individuals regarding obesity using waist-to-height ratio as an objective measurement of obesity. Using the Korean National Health and Nutrition Examination Survey for 2008-2011, we showed that false-reporting behavior was significantly associated with socio-economic status. Furthermore, we presented that subjective perception of obesity yielded misleading estimates in both the determinants and the consequences of obesity.

Estimating population attributable fractions to quantify the health burden of obesity

PURPOSE

Obesity is a highly prevalent condition in the United States and elsewhere and is associated with increased mortality and morbidity. Here, we discuss some issues involved in quantifying the health burden of obesity using population attributable fraction (PAF) estimates and provide examples.

METHODS

We searched PubMed for articles reporting attributable fraction estimates for obesity. We reviewed eligible articles to identify methodological concerns and tabulated illustrative examples of PAF estimates for obesity relative to cancer, diabetes, cardiovascular disease, and all-cause mortality.

RESULTS

There is considerable variability among studies regarding the methods used for PAF calculation and the selection of appropriate counterfactuals. The reported estimates ranged from 5% to 15% for all-cause mortality, -0.2% to 8% for all-cancer incidence, 7% to 44% for cardiovascular disease incidence, and 3% to 83% for diabetes incidence.

CONCLUSIONS

To evaluate a given estimate, it is important to consider whether the exposure and outcome were defined similarly for the PAF and for the relative risks, whether the relative risks were suitable for the population at hand, and whether PAF was calculated using correct methods. Strong causal assumptions are not necessarily warranted. In general, PAFs for obesity may be best considered as indicators of association.

Economic impact of adult obesity on health systems: a systematic review

BACKGROUND

Obesity represents an important public health issue. An assessment of its costs would be useful to provide recommendations for policy and decision-making strategies. The aims of our study were to carry out a systematic review to assess the economic burden of adult obesity in terms of direct and indirect costs and to perform a quality appraisal of the analysed studies.

METHODS

A literature search was carried out on PubMed, Scopus and Cochrane Library to retrieve cost-of-illness (COI) analyses focused on adult (aged 18 years or more) overweight or obese people and published up to 2013. COI analyses that considered direct and indirect costs were included. Each included manuscript was independently appraised by three groups of researchers on the basis of the British Medical Journal Drummond's checklist.

RESULTS

Approximately 2044 articles were initially retrieved, and 17 were included in the current review. The included studies showed a medium-high-quality level. The available studies seemed to be heterogeneous both in terms of methodology and results reporting. However, as many studies have been conducted from the payer perspective, just direct medical costs can be considered exhaustive. As only three studies included considered also indirect costs, there is no strong evidence to give a comprehensive picture of this phenomenon also from the societal perspective.

CONCLUSION

The review confirmed that obesity absorbs a huge amount of health-care resources. Further research is therefore needed to better understand the economic impact and to identify and promote public health strategies to tackle obesity.

Body mass index and all-cause mortality in a large prospective cohort of white and black U.S. Adults

Remaining controversies on the association between body mass index (BMI) and mortality include the effects of smoking and prevalent disease on the association, whether overweight is associated with higher mortality rates, differences in associations by race and the optimal age at which BMI predicts mortality. To assess the relative risk (RR) of mortality by BMI in Whites and Blacks among subgroups defined by smoking, prevalent disease, and age, 891,572 White and 38,119 Black men and women provided height, weight and other information when enrolled in the Cancer Prevention Study II in 1982. Over 28 years of follow-up, there were 434,400 deaths in Whites and 18,702 deaths in Blacks. Cox proportional-hazards regression was used to estimate multivariable-adjusted relative risks (RR) and 95% confidence intervals (CI). Smoking and prevalent disease status significantly modified the BMI-mortality relationship in Whites and Blacks; higher BMI was most strongly associated with higher risk of mortality among never smokers without prevalent disease. All levels of overweight and obesity were associated with a statistically significantly higher risk of mortality compared to the reference category (BMI 22.5-24.9 kg/m2), except among Black women where risk was elevated but not statistically significant in the lower end of overweight. Although absolute mortality rates were higher in Blacks than Whites within each BMI category, relative risks (RRs) were similar between race groups for both men and women (p-heterogeneity by race  = 0.20 for men and 0.23 for women). BMI was most strongly associated with mortality when reported before age 70 years. Results from this study demonstrate for the first time that the BMI-mortality relationship differs for men and women who smoke or have prevalent disease compared to healthy never-smokers. These findings further support recommendations for maintaining a BMI between 20-25 kg/m2 for optimal health and longevity.

Overweight patients achieve ideal body weight following curative gastrectomy resulting in better long-term prognosis

BACKGROUND

The relationship between body mass index (BMI) and long-term outcome in gastric cancer patients following radical gastrectomy continues to be debated. We investigated the association between BMI, clinicopathological features, and prognosis in Chinese gastric carcinoma patients.

METHODS

A retrospective consecutive cohort study was performed on 1,296 patients who underwent gastrectomy with curative intent at the Tianjin Cancer Institute Hospital between 1999 and 2004. The clinicopathological characteristics, overall 5-year survival rate (OS), and preoperative and six-month postoperative BMIs of both overweight (BMI ≥ 25 kg/m(2); H-BMI; n = 364) and non-overweight (BMI <25 kg/m(2); N-BMI; n = 932) patients were compared.

RESULTS

Among these patients, 364 (28.1 %) were overweight. The OS was significantly higher in the H-BMI than N-BMI group (33.2 vs. 24.1 %, respectively; p < 0.001). Preoperative and six-month postoperative BMIs were 27.1 ± 2.0 and 24.8 ± 2.0 kg/m(2), respectively, in the H-BMI group (p < 0.001), whereas they were 21.7 ± 2.2 and 20.7 ± 2.2 kg/m(2), respectively, in the N-BMI group (p = 0.007). There was significantly better differentiation (p = 0.034), less distant metastases (p = 0.006), and a lower metastatic lymph node ratio (p = 0.014) observed in the H-BMI groups. Multivariate analyses indicated age, BMI, pathological tumor depth, distant metastases, metastatic lymph node ratio, and tumor size as independent prognostic factors.

CONCLUSIONS

Our findings suggest that overweight patients were less likely to have tumors with aggressive features and can achieve ideal body weight following curative gastrectomy, possibly resulting in better long-term prognosis.

Overweight, obesity and thyroid cancer risk: a meta-analysis of cohort studies

OBJECTIVE

This meta-analysis examined the relationship between excess body weight or body mass index (BMI) and risk of thyroid cancer.

METHODS

PubMed(®), MEDLINE(®), EMBASE™ and Academic Search™ Premier databases were searched to identify cohort studies examining the effect of being overweight or obese on the risk of thyroid cancer.

RESULTS

The inclusion criteria were met by seven cohort studies (total number of thyroid cancer cases, 5154). The pooled relative risk (RR) of thyroid cancer was 1.13 (95% confidence interval [CI] 1.04, 1.22) for overweight. Obesity was also linked with increased thyroid cancer risk in males and females, the strength of the association increasing with increasing BMI. The combined RR of thyroid cancer was 1.18 (95% CI 1.11, 1.25) for excess body weight (overweight and obesity combined). Being overweight was associated with a significant increase in thyroid cancer risk among non-Asians, but not among Asians. Overweight, obesity and excess body weight were all associated with papillary thyroid carcinoma risk.

CONCLUSIONS

The association between overweight/obesity/excess body weight and thyroid cancer risk was confirmed.

Central obesity and albuminuria: both cross-sectional and longitudinal studies in Chinese

Background

Albuminuria is recognized as a marker of vascular dysfunction. Central obesity increases the risk of cardiovascular disease. Little is known about the association between albuminuria and central obesity in Chinese. We aimed to assess the association between central obesity and prevalence and incidence of albuminuria in a middle-aged population-based cohort study.

Methods

This is a cross-sectional and longitudinal cohort study. A total of 2350 subjects aged ≥40 years were recruited in 2004 in Taiwan for cross-sectional analysis. Longitudinal analysis included 1432 baseline normoalbuminuria subjects with a mean 2.8 years follow-up, 67 of whom exhibited incident albuminuria. Albuminuria was defined as urinary albumin-to-creatinine ratio ≥30 mg/g creatinine. Multiple logistic regression analyses were used to evaluate the relationship between central obesity and prevalence and incidence of albuminuria after adjustment for age, gender, body mass index, blood pressure, renal function, glucose, high sensitivity c-reactive protein, smoking, betel nut chewing, alcohol drinking, and physical activity.

Results

At baseline, albuminuria is significantly associated with central obesity. The adjusted odds ratio of having albuminuria among subjects with central obesity was 1.73(95% confidence interval (CI): 1.04–2.85), compared to the subjects without central obesity. In multivariable models, participants with central obesity at baseline had a 112% increase in risk of incident albuminuria (adjusted incidence rate ratio (95% CI): 2.12(1.01–4.44)) compared with participants with non-central obesity.

Conclusions

Abdominal adiposity was independently associated with increased prevalence and incidence of albuminuria in Chinese. The mechanisms linking adiposity and albuminuria need to be addressed.

WITHDRAWN: Effect of obesity at the pathologic response to neoadjuvant chemotherapy among premenopausal Tunisian women with breast cancer

In this article, we evaluated BMI and response to neoadjuvant chemotherapy (NC) in premenopausal Tunisian women with operable breast cancer. From May 2006 to July 2009, 800 patients were diagnosed and received NC from CHU Farhat Hached (Sousse, Tunisia). Patients were categorized as obese (BMI >/=30 kg/m(2)), overweight (25 </= BMI < 30 kg/m(2)), or normal/underweight (BMI <25 kg/m(2)). Logistic regression was used to examine associations between BMI and pathologic complete response (pCR). Breast cancer-specific, progression-free, and overall survival times were examined using the Kaplan-Meier method and Cox proportional hazards regression analysis. Median age was 42 years; 27% of patients were obese, 25% were overweight, and 48% were normal or underweight. In the univariate model, there was a significant difference in pCR to NC for obese compared with normal/underweight patients. In multivariate analysis, there was no significant difference in pCR for obese compared to normal weight patients. Overweight and the combination of overweight and obese patients were significantly less likely to have a pCR (odds ratio (OR) = 0.59; 95% confidence interval (CI), 0.37-0.95; and OR = 0.67; 95% CI, 0.45-0.99, respectively). Higher BMI was associated with worse pCR to NC. So, its association with worse overall survival suggests that greater attention should be focused on this risk factor to optimize the care of breast cancer patients.

Impact of obesity on bowel preparation for colonoscopy

BACKGROUND & AIMS

An inadequately cleansed colon can lead to missed lesions, repeat procedures, increased cost, and complications from colonoscopy. Because obesity, with its known link to colorectal neoplasia, might be associated with inadequate bowel cleansing, we investigated the impact of increased body mass index (BMI) on quality of bowel preparation at colonoscopy.

METHODS

All colonoscopy procedures performed at a tertiary referral center during a 4-month period were evaluated. Bowel preparation was assigned a unique composite outcome score that took into account a subjective bowel preparation score, earlier recommendation for follow-up colonoscopy as a result of inadequate bowel preparation, and the endoscopist's confidence in adequate evaluation of the colon. Univariate and multivariate logistic regression analyses were performed to identify the role of BMI in predicting an inadequate bowel preparation.

RESULTS

During the study period, 1588 patients (59.1% female; mean age, 57.4 +/- 0.34 years) fulfilled inclusion criteria. An abnormal BMI (> or =25) was associated with an inadequate composite outcome score (P = .002). In multivariate logistic regression analyses, both BMI > or =25 (P = .04) and > or =30 (P = .006) were retained as independent predictors of inadequate bowel preparation. Each unit increase in BMI increased the likelihood of an inadequate composite outcome score by 2.1%. Additional independent predictors of inadequate preparation exponentially increased the likelihood of an inadequate composite outcome score; 7 additional risk factors identified 97.5% of overweight patients with an inadequate composite outcome score.

CONCLUSIONS

Obesity is an independent predictor of inadequate bowel preparation at colonoscopy. The presence of additional risk factors further increases the likelihood of a poorly cleansed colon.

Obesity and Risk of Cancer in Postmenopausal Korean Women

Purpose

To evaluate an association between obesity, measured by body mass index (BMI; kg/m2), and risk of cancer at individual and all sites in postmenopausal women.

Methods

A cohort of 170,481 postmenopausal Korean women who were age 40 to 64 years at baseline measurement of BMI was observed prospectively from 1994 to 2003 for cancer incidence. Multivariable adjusted proportional hazard models were used for evaluating the association.

Results

Women with a BMI of 30 kg/m2 or higher had a 23% higher risk of cancer than women with a BMI between 21.0 and 22.9 kg/m2 (hazard ratio = 1.23; 95% CI, 1.08 to 1.41). According to the increase in BMI level, significant positive trends existed in cancers of colon, breast, corpus uteri, and kidney with hazard ratios of 1.05 (95% CI, 1.02 to 1.08), 1.07 (95% CI, 1.05 to 1.10), 1.13 (95% CI, 1.07 to 1.20), and 1.08 (95% CI, 1.02 to 1.15), respectively, for the increase of BMI by 1 kg/m2. When the analysis was limited to never-smokers, women with a BMI of 25 kg/m2 or higher showed a significantly increased risk of cancers of the colon, breast, corpus uteri, and kidney and leukemia compared with the normal BMI (18.5 to 22.9 kg/m2) group.

Conclusion

Although variations exist between the individual cancer sites, obesity was associated with an overall increased risk of cancer in postmenopausal Korean women. To reduce the risk of cancer, active strategies to prevent obesity should be implemented in postmenopausal women.

Muscularity and adiposity in addition to net acid excretion as predictors of 24-h urinary pH in young adults and elderly

OBJECTIVE

In patients with nephrolithiasis, an inverse relationship between 24-h urinary pH (24h-UpH) and body weight has been reported. Whether body composition indices and 24h-UpH are similarly associated in healthy subjects needs investigation.

DESIGN

Cross-sectional, retrospective analysis.

SETTING

Dortmund, Germany and Gothenburg, Sweden.

SUBJECTS

Healthy young adults (18-23 years; n=117) and elderly (55-75 years; n=85) having a mean body mass index (BMI) of 22.80+/-3.4 and 25.3+/-3.9 kg/m2, respectively.

METHODS

Anthropometric data, 24h-UpH, and 24-h urinary excretion rates of net acid (NAE), creatinine, and urea were determined. After adjusting for urea (reflecting protein intake), renal creatinine output was used as a biochemical marker for muscularity. The BMI served as a marker of adiposity.

RESULTS

NAE, body weight, and BMI were significantly (P<0.05) higher, and height and creatinine significantly lower in the elderly, whereas body-surface area (BSA) was not different. Step-wise multiple regression analysis using BSA-corrected urinary variables revealed NAE as the primary predictor of 24h-UpH (with R2 values of 0.64 and 0.68 in young adults and elderly, respectively, P<0.0001), followed by urea (P<0.0001), creatinine (P<0.05), and BMI (P<0.05 for the young adults and P=0.12 for the elderly). These associations were negative for NAE and BMI, and positive for urea and creatinine.

CONCLUSIONS

Muscularity (i.e. creatinine adjusted for urea) and particularly in the group of young adults, adiposity (i.e. BMI) proved to be modest, but significant predictors of 24h-UpH. Future research should focus on more obese subjects in whom insulin resistance and particular kidney functions should also be examined to further substantiate the role of obesity in low-urine pH-associated conditions, for example, nephrolithiasis.