Sex and Race Differences in Obesity-Related Genetic Susceptibility and Risk of Cardiometabolic Disease in Older US Adults

Importance

The fat mass and obesity-associated gene (FTO) is associated with obesity phenotypes, but the association is inconsistent across populations. Within-population differences may explain some of the variability observed.

Objective

To investigate sex differences in the association between FTO single-nucleotide variants (SNVs) and obesity traits among self-identified non-Hispanic Black and non-Hispanic White US adults, to examine whether the SNVs were associated with cardiometabolic diseases, and to evaluate whether obesity mediated the association between FTO SNVs and cardiometabolic diseases.

Design, Setting, and Participants

This cross-sectional study used data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a US population-based cohort study with available genetic data (assayed in 2018) and phenotypic data at baseline (enrolled 2003-2007). Participants were aged 45 to 98 years at baseline. Data were analyzed from October 2021 to October 2022.

Exposures

Eleven SNVs in the FTO gene present among both Black and White participants.

Main Outcomes and Measures

Objectively measured obesity indicators (body mass index and waist-to-height ratio), objectively measured and/or self-reported cardiometabolic diseases (hypertension, stroke history, heart disease, and diabetes), and self-reported social-economic and psychosocial status.

Results

A total of 10 447 participants (mean [SD] age, 64.4 [9.7] years; 5276 [55.8%] women; 8743 [83.7%] Black and 1704 [16.3%] White) were included. In the White group, 11 FTO SNVs were significantly associated with obesity, hypertension, and diabetes using linear models (eg, body mass index: β = 0.536; 95% CI, 0.197-0.875), but none of the FTO SNVs were associated with obesity traits in the Black group. White males had a higher risk of obesity while White females had a higher risk of hypertension and diabetes. However, 1 FTO SNV (rs1121980) was associated with a direct increase in the risk of heart disease in Black participants not mediated by obesity (c' = 0.145 [SE, 0.0517]; P = .01).

Conclusions and Relevance

In this cross-sectional study of obesity phenotypes and their association with cardiometabolic diseases, the tested FTO SNVs reflected sex differences in White participants. Different patterns of associations were observed among self-identified Black participants. Therefore, these results could inform future work discovering risk alleles or risk scores unique to Black individuals or further investigating genetic risk in all US residents.

Design, analysis, and interpretation of treatment response heterogeneity in personalized nutrition and obesity treatment research

It is increasingly assumed that there is no one-size-fits-all approach to dietary recommendations for the management and treatment of chronic diseases such as obesity. This phenomenon that not all individuals respond uniformly to a given treatment has become an area of research interest given the rise of personalized and precision medicine. To conduct, interpret, and disseminate this research rigorously and with scientific accuracy, however, requires an understanding of treatment response heterogeneity. Here, we define treatment response heterogeneity as it relates to clinical trials, provide statistical guidance for measuring treatment response heterogeneity, and highlight study designs that can quantify treatment response heterogeneity in nutrition and obesity research. Our goal is to educate nutrition and obesity researchers in how to correctly identify and consider treatment response heterogeneity when analyzing data and interpreting results, leading to rigorous and accurate advancements in the field of personalized medicine.

Relationship Between Food Security Status in a Caregiver's Family of Origin and Current Feeding Practices Among Low-Income, Single, Female Primary Caregivers

A child's familial environment is paramount to the formation and maintenance of their health behaviors. Factors that influence a child's health behaviors include parental modeling, types of available food, timing of food availability, and characteristics of the home environment. Previous research has demonstrated an association between a caregiver's current food security status and feeding practices, but no studies have explored the association between food security in the caregiver's childhood and their current feeding practices. This study investigates the relationship between parental food insecurity (both current and childhood) and child feeding practices. The US Household Food Security Survey and the Child Feeding Questionnaire were completed by 103 low-income, single, female primary caregivers. Results indicated that caregivers who reported current food insecurity expressed greater tendency to pressure their children to eat. Caregivers who reported food insecurity during their childhood also expressed greater tendency to pressure their children to eat and a greater concern about their child's weight. These findings can serve in both research and clinical efforts as an early screening tool to indicate families most in need of accessible resources. Findings also help to highlight the transgenerational nature of food insecurity, including its residual effects on health behaviors.

Determining an Appropriate Statistical Model when Assessing the Association between Obesity and Mortality

Objectives

To determine a statistical model appropriate to assess the association between Obesity and mortality using epidemiological data. We hypothesized that the model with the lowest AIC, BIC, and lowest Sobol's Indices is the appropriate model, compared to the others, to assess the association between obesity and mortality.

Methods

The datasets used were the National Child Development Study, the Health Retirement Study, the National Health Interview Survey, and the National Health and Nutrition Examination Survey. The statistical models compared were the Cox PH Model and the AFT Model. For the AFT Model, we used the Weibull Distribution, Lognormal Distribution, and Exponential Distribution. Body mass index (BMI) was used as a proxy for obesity, the exposure of interest. Mortality, the event of interest, was calculated using age and a death indicator of the participants. Covariates were sex, socioeconomic status (SES), education, smoking status, drinking status. The interactions were between BMI and SES, BMI and Sex, BMI and Smoking Status.

Results

The results of the NCDS dataset indicated that the Cox PH Model has an AIC of 11528.81, BIC of 11611.81 without interactions, an AIC of 11502.04, and BIC of 11640.36 with interaction. The Cox PH model has the highest AIC and BIC regardless of the inclusion of interactions compared to the AFT Models. The AFT model with a Weibull distribution had the lowest AIC and BIC (without interaction: 8367.61 and 8521.30, respectively and with interaction: 8346.29 and 8592.19, respectively). The Sobol's Indices for the models, without interaction, were close to zero for all covariates except education, where all models were close to one. However, with interactions, the Sobol's Indices of the education covariate decreases for all AFT Models though the Cox PH Model remains the highest and without change.

Conclusions

Given our sample and specified model, the AFT model with a Weibull distribution appeared to fit the data better relative to the Cox PH Model or the other AFT Models. The Cox PH model is more sensitive to interactions than the AFT Models.

Funding Sources

National Institute of Aging (NIA): 3R01AG057703-02S1

Re-Validation of the COmprehensive Score for Financial Toxicity (COST): Assessing the Scale's Utility in Chronic Disease Populations

Objective:

To report the psychometric properties of the COmprehensive Score for financial Toxicity (COST) patient-reported outcome measure (PROM), an 11-item scale previously validated among patients diagnosed with cancer and receiving chemotherapy.

Methods:

Data come from a cross-sectional survey (n = 2755 response rate of 87%) of participants in a remote digital health coaching intervention collected between January 2017 and February 2019.

Results:

COST demonstrated very good internal consistency (Cronbach’s alpha = .89) and good convergent validity. Lower financial toxicity was associated with improved physical and mental well-being HRQOL measures after controlling for covariates (b = 0.13, P < .0001; b = 0.28, P < .0001, respectively). Supplemental analyses indicated that the COST instrument loaded on 2 factors.

Conclusions:

The COST measure of financial toxicity has good internal consistency and predictive validity in a sample of patients with chronic conditions. However, contrary to previous research examining the psychometric properties of COST in a sample of individuals with cancer, which found COST to be unidimensional, our analyses indicated that the COST measure of financial toxicity is multidimensional in a sample of individuals with chronic conditions. In particular, the items that asked about “general financial wellbeing” loaded on the second factor while “illness-related financial wellbeing” loaded on the first.

Experimentally Manipulated Low Social Status and Food Insecurity Alter Eating Behavior Among Adolescents: A Randomized Controlled Trial

OBJECTIVE

This randomized trial experimentally manipulated social status to assess effects on acute eating behavior and 24-hour energy balance.

METHODS

Participants (n = 133 Hispanics; age 15-21 years; 60.2% females) were randomized to low social status ("LOW") or high social status ("HIGH") conditions in a rigged game of Monopoly (Hasbro, Inc.). Acute energy intake in a lunchtime meal was measured by food scales. Twenty-four-hour energy balance was assessed via summation of resting metabolic rate (metabolic cart), physical activity energy expenditure (accelerometer), thermic effect of food, and subtraction of twenty-four-hour energy intake (food diary).

RESULTS

In the total sample, no significant differences were observed by study condition at lunchtime. LOW females consumed a greater percent of lunchtime daily energy needs (37.5%) relative to HIGH females (34.3%); however, this difference was not statistically significant (P = 0.291). In males, however, LOW consumed significantly less (36.5%) of their daily energy needs relative to HIGH males (45.8%; P = 0.001). For 24-hour energy balance, sex differences were nearly significant (P = 0.057; LOW females: surplus +200 kcal; HIGH males: surplus +445 kcal). Food-insecure individuals consumed a nearly significant greater lunchtime percent daily energy than those with food security (40.7% vs. 36.3%; P = 0.0797).

CONCLUSIONS

The data demonstrate differential acute and 24-hour eating behavior responses between Hispanic male and female adolescents in experimentally manipulated conditions of low social status.

GDM Acts as a Moderator Between Pregnancy BMI and Metabolic Syndrome Severity Score

Objectives

Overweight or obesity is a risk factor for Metabolic Syndrome (MetS), as is a history of gestational diabetes (GDM). Many women with GDM are overweight in pregnancy, and so it is difficult to disentangle the effects of pregnancy BMI (pregBMI) from GDM. The purpose of this study was to examine whether GDM moderates the association between pregBMI and MetS severity Z-scores 4–10 years following pregnancy. We hypothesized that the positive association between pregBMI and MetS Z-scores would be stronger in women with GDM compared to women without GDM.

Methods

Data for this analysis were drawn from N = 179 women enrolled in a cross-sectional study examining obesity and cardiometabolic disease risk in mother-child dyads. Women with GDM were oversampled relative to the prevalence in the general population. Women were eligible for inclusion if they delivered a healthy term infant 4–10 years prior to enrolling in this study, and were aged 20–36 years at delivery. PregBMI was calculated using measured body weight recorded in the medical record from their first prenatal visit. GDM status was retrieved from medical records. Waist circumference and blood pressure were measured using standard clinical procedures, and a fasting blood draw was obtained to measure glucose, triglycerides, and HDL-cholesterol. MetS Z-scores were measured using the method of Gurka and DeBoer (Metabolism, 63(2), 218–225; Clinical and Translational Science – Informatics and Technology group).

Results

The association between pregBMI and MetS was significantly modified by GDM status (P &lt; 0.001) such that pregBMI was more strongly associated with MetS in women with GDM. Among women with a pregBMI of 30.9 (the sample mean), the mean difference in MetS Z-scores between conditions (those with or without GDM) is 0.65 SD units, a difference that grows larger at higher levels of pregBMI.

Conclusions

These results suggest greater MetS severity in women with GDM and a high pregBMI compared to women with a high pregBMI but without GDM. Future research should prospectively examine whether MetS is present in early pregnancy for women who develop GDM, and whether there are other modifiable factors that could reduce the risk for MetS among women with overweight or obesity in pregnancy.

Funding Sources

American Heart Association, NHLBI T32 training grant.

Youth Subjective Social Status (SSS) is Associated with Parent SSS, Income, and Food Insecurity but not Weight Loss Among Low-Income Hispanic Youth

OBJECTIVE

Subjective social status (SSS), perceived rank in the social ladder, is associated with weight, but determinants of SSS in youth remain unknown. Relationships between youth SSS and income, food insecurity, parent SSS, and BMI change were investigated during an obesity intervention.

METHODS

Data came from a family-centered, community-based obesity intervention for low-income families. Parent and youth SSS were assessed using a validated, age-appropriate SSS scale. Food insecurity and socioeconomic factors were assessed in parents; child and parent weight-related data were measured at baseline and post intervention.

RESULTS

Participants included 110 primarily Hispanic (97%) low-income youth and their parents. Food insecurity was reported in 66.4% of families. Youth SSS was positively associated with parent SSS (P = 0.0014). In both parents and children, the association between income and SSS was moderated by food insecurity such that lower income was more strongly associated with lower SSS among food-insecure households (P = 0.0286 and P = 0.0327, respectively). Youth SSS was not associated with youth BMI reduction.

CONCLUSIONS

Youth SSS was not predictive of weight loss in this intervention. Intriguingly, the association between income and SSS was modified by food insecurity, suggesting that food insecurity shapes the contribution of socioeconomic factors to one's perceived social status.

Social status and energy intake: a randomized controlled experiment

While the inverse association between socioeconomic status (SES) and obesity in high gross domestic product countries is well established using observational data, the extent to which the association is due to a true causal effect of SES and, if so, the mechanisms of this effect remain incompletely known. To assess the influence of social status on obesity via energy intake, we randomized individuals to a higher or lower social status and observed subsequent energy intake. College students between the ages of 18 and 25 were randomized to social status and were operationalized as being a leader or follower in a partner activity as purportedly determined by a (bogus) test of leadership ability. Investigators were blinded to treatment assignment. Immediately after being told their leadership assignment, paired participants were provided with platters of food. Energy intake was objectively measured in kilocalories (kcal) consumed, and paired t-tests were used to test for significant differences in intake between leaders and followers. A total of 60 participants were included in the final analysis (males = 28, females = 32). Overall, no difference in energy intake was observed between leaders and followers, consuming an average of 575.3 and 579.8 kcal, respectively (diff = 4.5 kcal, P = 0.94). The null hypothesis of no effect of social status, operationalized as assignment to a leadership position in a small-group activity, on energy intake was not rejected.

Randomization to randomization probability: Estimating treatment effects under actual conditions of use

Blinded randomized controlled trials (RCT) require participants to be uncertain if they are receiving a treatment or placebo. Although uncertainty is ideal for isolating the treatment effect from all other potential effects, it is poorly suited for estimating the treatment effect under actual conditions of intended use-when individuals are certain that they are receiving a treatment. We propose an experimental design, randomization to randomization probabilities (R2R), which significantly improves estimates of treatment effects under actual conditions of use by manipulating participant expectations about receiving treatment. In the R2R design, participants are first randomized to a value, π, denoting their probability of receiving treatment (vs. placebo). Subjects are then told their value of π and randomized to either treatment or placebo with probabilities π and 1-π, respectively. Analysis of the treatment effect includes statistical controls for π (necessary for causal inference) and typically a π-by-treatment interaction. Random assignment of subjects to π and disclosure of its value to subjects manipulates subject expectations about receiving the treatment without deception. This method offers a better treatment effect estimate under actual conditions of use than does a conventional RCT. Design properties, guidelines for power analyses, and limitations of the approach are discussed. We illustrate the design by implementing an RCT of caffeine effects on mood and vigilance and show that some of the actual effects of caffeine differ by the expectation that one is receiving the active drug. (PsycINFO Database Record

Social Relationships, Gender, and Recovery From Mobility Limitation Among Older Americans

OBJECTIVES

Evidence suggests social relationships may be important facilitators for recovery from functional impairment, but the extant literature is limited in its measurement of social relationships including an over emphasis on filial social support and a paucity of nationally representative data.

METHODS

Using data from Waves 4-9 (1998-2008) of the Health and Retirement Study (HRS), this research examines the association between social relationships and recovery from severe mobility limitation (i.e., difficulty walking one block or across the room) among older Americans. Using a more nuanced measure of recovery that includes complete and partial recovery, a series of discrete-time event history models with multiple competing recovery outcomes were estimated using multinomial logistic regression.

RESULTS

Providing instrumental support to peers increased the odds of complete and partial recovery from severe mobility limitation, net of numerous social, and health factors. Having relatives living nearby decreased the odds of complete recovery, while being engaged in one's neighborhood increased the odds of partial recovery. The influence of partner status on partial and complete recovery varied by gender, whereby partnered men were more likely to experience recovery relative to partnered women. The effect of neighborhood engagement on partial recovery also varied by gender. Disengaged women were the least likely to experience partial recovery compared with any other group.

DISCUSSION

The rehabilitative potential of social relationships has important policy implications. Interventions aimed at encouraging older adults with mobility limitation to be engaged in their neighborhoods and/or provide instrumental support to peers may improve functional health outcomes.

Packet randomized experiments for eliminating classes of confounders

BACKGROUND

Although randomization is considered essential for causal inference, it is often not possible to randomize in nutrition and obesity research. To address this, we develop a framework for an experimental design-packet randomized experiments (PREs), which improves causal inferences when randomization on a single treatment variable is not possible. This situation arises when subjects are randomly assigned to a condition (such as a new roommate) which varies in one characteristic of interest (such as weight), but also varies across many others. There has been no general discussion of this experimental design, including its strengths, limitations, and statistical properties. As such, researchers are left to develop and apply PREs on an ad hoc basis, limiting its potential to improve causal inferences among nutrition and obesity researchers.

METHODS

We introduce PREs as an intermediary design between randomized controlled trials and observational studies. We review previous research that used the PRE design and describe its application in obesity-related research, including random roommate assignments, heterochronic parabiosis, and the quasi-random assignment of subjects to geographic areas. We then provide a statistical framework to control for potential packet-level confounders not accounted for by randomization.

RESULTS

Packet randomized experiments have successfully been used to improve causal estimates of the effect of roommates, altitude, and breastfeeding on weight outcomes. When certain assumptions are met, PREs can asymptotically control for packet-level characteristics. This has the potential to statistically estimate the effect of a single treatment even when randomization to a single treatment did not occur.

CONCLUSIONS

Applying PREs to obesity-related research will improve decisions about clinical, public health, and policy actions insofar as it offers researchers new insight into cause and effect relationships among variables.