Body mass index and mortality in non-Hispanic black adults in the NIH-AARP Diet and Health Study

Body mass index and all-cause mortality in a 21st century U.S. population: A National Health Interview Survey analysis

INTRODUCTION

Much of the data on BMI-mortality associations stem from 20th century U.S. cohorts. The purpose of this study was to determine the association between BMI and mortality in a contemporary, nationally representative, 21st century, U.S. adult population.

METHODS

This was a retrospective cohort study of U.S. adults from the 1999-2018 National Health Interview Study (NHIS), linked to the National Death Index (NDI) through December 31st, 2019. BMI was calculated using self-reported height & weight and categorized into 9 groups. We estimated risk of all-cause mortality using multivariable Cox proportional hazards regression, adjusting for covariates, accounting for the survey design, and performing subgroup analyses to reduce analytic bias.

RESULTS

The study sample included 554,332 adults (mean age 46 years [SD 15], 50% female, 69% non-Hispanic White). Over a median follow-up of 9 years (IQR 5-14) and maximum follow-up of 20 years, there were 75,807 deaths. The risk of all-cause mortality was similar across a wide range of BMI categories: compared to BMI of 22.5-24.9 kg/m2, the adjusted HR was 0.95 [95% CI 0.92, 0.98] for BMI of 25.0-27.4 and 0.93 [0.90, 0.96] for BMI of 27.5-29.9. These results persisted after restriction to healthy never-smokers and exclusion of subjects who died within the first two years of follow-up. A 21-108% increased mortality risk was seen for BMI ≥30. Older adults showed no significant increase in mortality between BMI of 22.5 and 34.9, while in younger adults this lack of increase was limited to the BMI range of 22.5 to 27.4.

CONCLUSION

The risk of all-cause mortality was elevated by 21-108% among participants with BMI ≥30. BMI may not necessarily increase mortality independently of other risk factors in adults, especially older adults, with overweight BMI. Further studies incorporating weight history, body composition, and morbidity outcomes are needed to fully characterize BMI-mortality associations.

A multivariate joint model to adjust for random measurement error while handling skewness and correlation in dietary data in an epidemiologic study of mortality

PURPOSE

A substantial proportion of global deaths is attributed to unhealthy diets, which can be assessed at baseline or longitudinally. We demonstrated how to simultaneously correct for random measurement error, correlations, and skewness in the estimation of associations between dietary intake and all-cause mortality.

METHODS

We applied a multivariate joint model (MJM) that simultaneously corrected for random measurement error, skewness, and correlation among longitudinally measured intake levels of cholesterol, total fat, dietary fiber, and energy with all-cause mortality using US National Health and Nutrition Examination Survey linked to the National Death Index mortality data. We compared MJM with the mean method that assessed intake levels as the mean of a person's intake.

RESULTS

The estimates from MJM were larger than those from the mean method. For instance, the logarithm of hazard ratio for dietary fiber intake increased by 14 times (from -0.04 to -0.60) with the MJM method. This translated into a relative hazard of death of 0.55 (95% credible interval: 0.45, 0.65) with the MJM and 0.96 (95% credible interval: 0.95, 0.97) with the mean method.

CONCLUSIONS

MJM adjusts for random measurement error and flexibly addresses correlations and skewness among longitudinal measures of dietary intake when estimating their associations with death.

The 2018 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) Score and All-Cause, Cancer, and Cardiovascular Disease Mortality Risk: A Longitudinal Analysis in the NIH-AARP Diet and Health Study

Background

The World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) published Cancer Prevention Recommendations in 2018 focused on modifiable lifestyle factors.

Objectives

The aim was to examine how adherence to WCRF/AICR recommendations via the 2018 WCRF/AICR score is associated with risk for all-cause, cancer, and cardiovascular disease (CVD) mortality outcomes among older US adults.

Methods

Baseline and follow-up questionnaire data (n = 177,410) were used to calculate weight, physical activity, and diet components of the 2018 WCRF/AICR score (0-7 total points). Adjusted HRs and 95% CIs were estimated, stratified by sex and smoking status.

Results

There were 16,055 deaths during a mean of 14.2 person-years. Each 1-point score increase was associated with a 9-26% reduced mortality risk for all outcomes, except for current male smokers' cancer mortality risk. When the score was categorized comparing highest (5-7 points) with lowest (0-2 points) scores, associations with reduced all-cause mortality risk were strongest in former smokers (HRmales: 0.51; 95% CI: 0.43, 0.61; HRfemales: 0.38; 95% CI: 0.31, 0.46), followed by current smokers (HRmales: 0.55; 95% CI: 0.34, 0.89; HRfemales: 0.44; 95% CI: 0.32, 0.59) and never smokers (HRmales: 0.57; 95% CI: 0.47, 0.70; HRfemales: 0.50; 95% CI: 0.41, 0.60). An association with cancer mortality risk was also seen in former smokers (HRmales: 0.59; 95% CI: 0.43, 0.81; HRfemales: 0.52; 95% CI: 0.37, 0.73) and female current (HRfemales: 0.55; 95% CI: 0.32, 0.96) and never (HRfemales: 0.57; 95% CI: 0.40, 0.80) smokers; findings were not statistically significant in other strata. For CVD mortality, highest compared with lowest scores were associated with a 49-73% risk reduction, except in male never and current smokers. In exploratory analysis, physical activity, body weight, alcohol, and plant-based foods were found to be predominant components in the score.

Conclusions

Greater 2018 WCRF/AICR scores were associated with lower mortality risk among older adults. Future research can explore how smoking modifies these relations, and further examine different populations and other cancer-relevant outcomes.

Anthropometric Risk Factors for Cancers of the Biliary Tract in the Biliary Tract Cancers Pooling Project

Biliary tract cancers are rare but highly fatal with poorly understood etiology. Identifying potentially modifiable risk factors for these cancers is essential for prevention. Here we estimated the relationship between adiposity and cancer across the biliary tract, including cancers of the gallbladder (GBC), intrahepatic bile ducts (IHBDC), extrahepatic bile ducts (EHBDC), and the ampulla of Vater (AVC). We pooled data from 27 prospective cohorts with over 2.7 million adults. Adiposity was measured using baseline body mass index (BMI), waist circumference, hip circumference, waist-to-hip, and waist-to-height ratios. HRs and 95% confidence intervals (95% CI) were estimated using Cox proportional hazards models adjusted for sex, education, race, smoking, and alcohol consumption with age as the time metric and the baseline hazard stratified by study. During 37,883,648 person-years of follow-up, 1,343 GBC cases, 1,194 EHBDC cases, 784 IHBDC cases, and 623 AVC cases occurred. For each 5 kg/m2 increase in BMI, there were risk increases for GBC (HR = 1.27; 95% CI, 1.19-1.36), IHBDC (HR = 1.32; 95% CI, 1.21-1.45), and EHBDC (HR = 1.13; 95% CI, 1.03-1.23), but not AVC (HR = 0.99; 95% CI, 0.88-1.11). Increasing waist circumference, hip circumference, waist-to-hip ratio, and waist-to-height ratio were associated with GBC and IHBDC but not EHBDC or AVC. These results indicate that adult adiposity is associated with an increased risk of biliary tract cancer, particularly GBC and IHBDC. Moreover, they provide evidence for recommending weight maintenance programs to reduce the risk of developing these cancers. SIGNIFICANCE: These findings identify a correlation between adiposity and biliary tract cancers, indicating that weight management programs may help minimize the risk of these diseases.

Comparative effects of the restriction method in two large observational studies of body mass index and mortality among adults

BACKGROUND

A method applied in some large studies of weight and mortality is to begin with a well-defined analytic cohort and use successive restrictions to control for methodologic bias and arrive at final analytic results.

MATERIALS AND METHODS

Two observational studies of body mass index and mortality allow a comparative assessment of these restrictions in very large data sets. One was a meta-analysis of individual participant data with a sample size of 8 million. The second was a study of a South Korean cohort with a sample size of 12 million. Both presented results for participants without pre-existing disease before and after restricting the sample to never-smokers and deleting the first 5 years of follow-up.

RESULTS

Initial results from both studies were generally similar, with hazard ratios (HRs) below 1 for overweight and above 1 for underweight and obesity. The meta-analysis showed higher HRs for overweight and obesity after the restrictions, including a change in the direction of the HR for overweight from 0·99 (95% CI: 0·98-1·01) to 1·11 (95% CI: 1·10, 1·11). The South Korean data showed little effect of the restrictions and the HR for overweight changed from 0·85 (95% CI: 0·84-0·86) to 0·91 (95% CI: 0·90, 0·91). The summary effect size for overweight was 0·90 (95% CI: 0·89-0·91) before restrictions and 1·02 (95% CI: 1·02, 1·03) after restrictions.

CONCLUSIONS

The effect of the restrictions is not consistent across studies, weakening the argument that analyses without such restrictions lack validity.

The Contribution of Weight Status to Black-White Differences in Mortality

This article examines the contribution of weight status to black-white (B-W) differences in mortality at ages 40-79 using data from the National Health and Nutrition Examination Survey. We measured body mass index (BMI) based on the highest BMI attained and contrasted the contribution of BMI to that of smoking and educational attainment. We estimated both additive and multiplicative models. In addition to estimating regression coefficients we asked what would happen to B-W differences in mortality if blacks had the BMI distribution of whites, the smoking prevalence of whites, or the educational distribution of whites. B-W differences in BMI account for close to 30 percent of the B-W difference in female mortality but only about 1 percent of the B-W difference in male mortality at ages 40-79. In contrast, smoking makes a much larger contribution to the B-W difference in male (17 percent) than female (6 percent) mortality. Differences in educational attainment in turn explain 19 to 25 percent of the B-W mortality difference among men and women, respectively. Our results underscore the importance of two key risk factors as well as educational attainment in generating B-W differences in mortality.

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.

Mediating Effect of Perceived Overweight on the Association between Actual Obesity and Intention for Weight Control; Role of Race, Ethnicity, and Gender

Background:

Although obesity is expected to be associated with intention to reduce weight, this effect may be through perceived overweight. This study tested if perceived overweight mediates the association between actual obesity and intention to control weight in groups based on the intersection of race and gender. For this purpose, we compared Non-Hispanic White men, Non-Hispanic White women, African American men, African American women, Caribbean Black men, and Caribbean Black women.

Methods:

National Survey of American Life, 2001–2003 included 5,810 American adults (3516 African Americans, 1415 Caribbean Blacks, and 879 Non-Hispanic Whites). Weight control intention was entered as the main outcome. In the first step, we fitted race/gender specific logistic regression models with the intention for weight control as outcome, body mass index as predictor and sociodemographics as covariates. In the next step, to test mediation, we added perceived weight to the model.

Results:

Obesity was positively associated with intention for weight control among all race × gender groups. Perceived overweight fully mediated the association between actual obesity and intention for weight control among Non-Hispanic White women, African American men, and Caribbean Black men. The mediation was only partial for Non-Hispanic White men, African American women, and Caribbean Black women.

Conclusions:

The complex relation between actual weight, perceived weight, and weight control intentions depends on the intersection of race and gender. Perceived overweight plays a more salient role for Non-Hispanic White women and Black men than White men and Black women. Weight loss programs may benefit from being tailored based on race and gender. This finding also sheds more light to the disproportionately high rate of obesity among Black women in US.

Sex and ethnic-origin specific BMI cut points improve prediction of 40-year mortality: the Israel GOH study

BACKGROUND

Although obesity has been associated with a higher risk for premature death, the sex and ethnic-origin specific body mass index (BMI) levels that are associated with increased mortality are controversial. We investigated the 40-year cumulative all-cause mortality, in relation to the BMI in adult life, among men and women originating from Yemen, Europe/America, Middle East and North Africa, using sex and ethnic-origin specific BMI cut points.

METHODS

A random stratified cohort (n = 5710) was sampled from the central population registry and followed since 1969 for vital status. Weight, height and blood pressure were measured, and smoking status was recorded at baseline. BMI was analysed according to conventional categories and according to sex and ethnic-origin specific quintiles.

RESULTS

Elevated and significant mortality hazard ratios (HRs) of 1.21 [95% confidence interval (CI) 1.00-1.45] for women and 1.22 (95%CI 1.03-1.44) for men were found for the highest origin-specific BMI quintile. In men, the lowest ethnic-origin specific quintile was also significantly associated with increased mortality (HR of 1.22 95% CI 1.03-1.45), adjusting for age, smoking and blood pressure. Obesity was associated with mortality in non-smokers (HR = 1.29, 95% CI 1.04-1.61 in men and HR = 1.46, 95% CI 1.19-1.79 in women), whereas leanness was associated with mortality only among smoking men (HR = 1.39, 95% CI 1.09-1.77).

CONCLUSION

Refinement of BMI categories using country of origin specific quintiles demonstrated significantly increased mortality in the upper quintile in both sexes, while according to the conventional values this association did not prevail in men. We propose the establishment of sex and origin-specific BMI categories when setting goals for disease prevention.

Racial Differences in Weight Loss Among Adults in a Behavioral Weight Loss Intervention: Role of Diet and Physical Activity

BACKGROUND

African-Americans lose less weight during a behavioral intervention compared with Whites, which may be from differences in dietary intake or physical activity.

METHODS

Subjects (30% African American, 70% White; n = 346; 42.4 ± 9.0 yrs.; BMI = 33.0 ± 3.7 kg/m2) in an 18-month weight loss intervention were randomized to a standard behavioral (SBWI) or a stepped-care (STEP) intervention. Weight, dietary intake, self-report and objective physical activity, and fitness were assessed at 0, 6, 12, and 18 months.

RESULTS

Weight loss at 18 months was greater in Whites (-8.74 kg with 95% CI [-10.10, -7.35]) compared with African Americans (-5.62 kg with 95% CI [-7.86, -3.37]) (P = .03) in the SBWI group and the STEP group (White: -7.48 kg with 95% CI [-8.80, -6.17] vs. African American: -4.41kg with 95% CI [-6.41, -2.42]) (P = .01). Patterns of change in dietary intake were not different between groups. Objective physical activity (PA) changed over time (P < .0001) and was higher in Whites when compared with African Americans (P = .01).

CONCLUSIONS

Whites lost more weight (3.10 kg) than African American adults. Although there were no differences in dietary intake, Whites had higher levels of objective PA and fitness. Thus, the discrepancy in weight loss may be due to differences in PA rather than dietary intake. However, the precise role of these factors warrants further investigation.

Cognitive function, body mass index and mortality in a rural elderly Chinese cohort

BACKGROUND

Previous studies have shown that poor cognition and low body mass index were associated with increased mortality. But few studies have investigated the association between cognition and mortality across the entire cognitive spectrum while adjusting for BMI. The objective of this study is to examine the associations between cognitive function, BMI and 7-year mortality in a rural elderly Chinese cohort.

METHODS

A prospective cohort of 2,000 Chinese age 65 and over from four rural counties in China were followed for 7-years. Cognitive function, BMI and other covariate information were obtained at baseline. Cox's proportional hazard models were used to determine the effects of cognitive function and BMI on mortality risk.

RESULTS

Of participants enrolled, 473 (23.7%) died during follow-up. Both lower cognitive function (HR = 1.48, p = 0.0049) and lower BMI (HR = 1.6, p < 0.0001) were independently associated with increased mortality risk compared to individuals with average cognitive function and normal weight. Higher cognitive function was associated with lower mortality risk (HR = 0.69, p = 0.0312). We found no significant difference in mortality risk between overweight/obese participants and those with normal weight.

CONCLUSIONS

Cognitive function and BMI were independent predictors of mortality risk. Intervention strategies for increasing cognitive function and maintaining adequate BMI may be important in reducing morality risk in the elderly population.

Therapy duration and long-term outcomes in extra-pulmonary tuberculosis

BACKGROUND

Tuberculosis is classified as either pulmonary or extra-pulmonary (EPTB). While much focus has been paid to pulmonary tuberculosis, EPTB has received scant attention. Moreover, EPTB is viewed as one wastebasket diagnosis, as "the other" which is not pulmonary.

METHODS

This is a retrospective cohort study of all patients treated for EPTB in the state of Texas between January 2000 and December 2005, who had no pulmonary disease. Clinical and epidemiological factors were abstracted from electronic records of the Report of Verified Case of Tuberculosis. The long-term outcome, which is death by December 2011, was established using the Social Security Administration Death Master File database. Survival in EPTB patients was compared to those with latent tuberculosis, as well as between different types of EPTB, using Cox proportional hazard models. A hybrid of the machine learning method of classification and regression tree analyses and standard regression models was used to identify high-order interactions and clinical factors predictive of long-term all-cause mortality.

RESULTS

Four hundred and thirty eight patients met study criteria; the median study follow-up period for the cohort was 7.8 (inter-quartile range 6.0-10.1) years. The overall all-cause mortality rate was 0.025 (95% confidence interval [CI]: 0.021-0.030) per 100 person-year of follow-up. The significant predictors of poor long-term outcome were age (hazard ratio [HR] for each year of age-at-diagnosis was 1.05 [CI: 1.04-1.06], treatment duration, type of EPTB and HIV-infection (HR = 2.16; CI: 1.22, 3.83). Mortality in genitourinary tuberculosis was no different from latent tuberculosis, while meningitis had the poorest long-term outcome of 46.2%. Compared to meningitis the HR for death was 0.50 (CI: 0.27-0.91) for lymphatic disease, 0.42 (CI: 0.21-0.81) for bone/joint disease, and 0.59 (CI: 0.27-1.31) for peritonitis. The relationship between mortality and therapy duration for each type of EPTB was a unique "V" shaped curve, with the lowest mortality observed at different therapy durations for each, beyond which mortality increased.

CONCLUSIONS

EPTB is comprised of several different diseases with different outcomes and durations of therapy. The "V" shaped relationship between therapy duration and outcome leads to the hypothesis that longer duration of therapy may lead to higher patient mortality.