Risk of all-cause mortality in abdominal obesity phenotypes: Tehran Lipid and Glucose Study

The effect of obesity phenotype changes on cardiovascular outcomes in adults older than 40 years in the prospective cohort of the Tehran lipids and glucose study (TLGS): joint model of longitudinal and time-to-event data

BACKGROUND

Obesity is a worldwide health concern with serious clinical effects, including myocardial infarction (MI), stroke, cardiovascular diseases (CVDs), and all-cause mortality. The present study aimed to assess the association of obesity phenotypes and different CVDs and mortality in males and females by simultaneously considering the longitudinal and survival time data.

METHODS

In the Tehran Lipid and Glucose Study (TLGS), participants older than three years were selected by a multi-stage random cluster sampling method and followed for about 19 years. In the current study, individuals aged over 40 years without a medical history of CVD, stroke, MI, and coronary heart disease were included. Exclusions comprised those undergoing treatment for CVD and those with more than 30% missing information or incomplete data. Joint modeling of longitudinal binary outcome and survival time data was applied to assess the dependency and the association between the changes in obesity phenotypes and time to occurrence of CVD, MI, stroke, and CVD mortality. To account for any potential sex-related confounding effect on the association between the obesity phenotypes and CVD outcomes, sex-specific analysis was carried out. The analysis was performed using packages (JMbayes2) of R software (version 4.2.1).

RESULTS

Overall, 6350 adults above 40 years were included. In the joint modeling of CVD outcome among males, literates and participants with a family history of diabetes were at lower risk of CVD compared to illiterates and those with no family history of diabetes in the Bayesian Cox model. Current smokers were at higher risk of CVD compared to non-smokers. In a logistic mixed effects model, odds of obesity phenotype was higher among participants with low physical activity, family history of diabetes and older age compared to males with high physical activity, no family history of diabetes and younger age. In females, based on the results of the Bayesian Cox model, participants with family history of diabetes, family history of CVD, abnormal obesity phenotype and past smokers had a higher risk of CVD compared to those with no history of diabetes, CVD and nonsmokers. In the obesity varying model, odds of obesity phenotype was higher among females with history of diabetes and older age compared to those with no history of diabetes and who were younger. There was no significant variable associated with MI among males in the Bayesian Cox model. Odds of obesity phenotype was higher in males with low physical activity compared to those with high physical activity in the obesity varying model, whereas current smokers were at lower odds of obesity phenotype than nonsmokers. In females, risk of MI was higher among those with family history of diabetes compared to those with no history of diabetes in the Bayesian Cox model. In the logistic mixed effects model, a direct and significant association was found between age and obesity phenotype. In males, participants with history of diabetes, abnormal obesity phenotype and older age were at higher risk of stroke in the Bayesian Cox model compared to males with no history of diabetes, normal obesity phenotype and younger persons. In the obesity varying model, odds of obesity phenotype was higher in males with low physical activity, family history of diabetes and older age compared to those with high physical activity, no family history of diabetes and who were younger. Smokers had a lower odds of obesity phenotype than nonsmokers. In females, past smokers and those with family history of diabetes were at higher risk of stroke compared to nonsmokers and females with no history of diabetes in the Bayesian Cox model. In the obesity varying model, females with family history of diabetes and older ages had a higher odds of obesity phenotype compared to those with no family history of diabetes and who were younger. Among males, risk of CVD mortality was lower in past smokers compared to nonsmokers in the survival model. A direct and significant association was found between age and CVD mortality. Odds of obesity phenotype was higher in males with a history of diabetes than in those with no family history of diabetes in the logistic mixed effects model.

CONCLUSIONS

It seems that modifications to metabolic disorders may have an impact on the heightened incidence of CVDs. Based on this, males with obesity and any type of metabolic disorder had a higher risk of CVD, stroke and CVD mortality (excluding MI) compared to those with a normal body mass index (BMI) and no metabolic disorders. Females with obesity and any type of metabolic disorder were at higher risk of CVD(, MI and stroke compared to those with a normal BMI and no metabolic disorders suggesting that obesity and metabolic disorders are related. Due to its synergistic effect on high blood pressure, metabolic disorders raise the risk of CVD.

All-cause mortality risk with different metabolic abdominal obesity phenotypes: the Rural Chinese Cohort Study

We aimed to investigate the association of metabolic obesity phenotypes with all-cause mortality risk in a rural Chinese population. This prospective cohort study enrolled 15 704 Chinese adults (38·86 % men) with a median age of 51·00 (interquartile range: 41·00-60·00) at baseline (2007-2008) and followed up during 2013-2014. Obesity was defined by waist circumference (WC: ≥ 90 cm for men and ≥ 80 cm for women) or waist-to-height ratio (WHtR: ≥ 0·5). The hazard ratio (HR) and 95 % CI for the risk of all-cause mortality related to metabolic obesity phenotypes were calculated using the Cox hazards regression model. During a median follow-up of 6·01 years, 864 deaths were identified. When obesity was defined by WC, the prevalence of participants with metabolically healthy non-obesity (MHNO), metabolically healthy obesity (MHO), metabolically unhealthy non-obesity (MUNO) and metabolically unhealthy obesity (MUO) at baseline was 12·12 %, 2·80 %, 41·93 % and 43·15 %, respectively. After adjusting for age, sex, alcohol drinking, smoking, physical activity and education, the risk of all-cause mortality was higher with both MUNO (HR = 1·20, 95 % CI 1·14, 1·26) and MUO (HR = 1·20, 95 % CI 1·13, 1·27) v. MHNO, but the risk was not statistically significant with MHO (HR = 0·99, 95 % CI 0·89, 1·10). This result remained consistent when stratified by sex. Defining obesity by WHtR gave similar results. MHO does not suggest a greater risk of all-cause mortality compared to MHNO, but participants with metabolic abnormality, with or without obesity, have a higher risk of all-cause mortality. These results should be cautiously interpreted as the representation of MHO is small.

Associations between metabolic score for visceral fat and the risk of cardiovascular disease and all-cause mortality among populations with different glucose tolerance statuses

AIMS

To investigate the associations between metabolic score for visceral fat (METS-VF) and clinical outcomes among populations with different glucose tolerance statuses.

METHODS

We analysed 6827 participants aged ≥ 40 years with different glucose tolerance statuses from a cohort study. The associations between METS-VF and cardiovascular disease (CVD) events and all-cause mortality were assessed using Cox regression, restricted cubic spline and receiver operating characteristic curves.

RESULTS

During a follow-up of 5.00 years, there were 338 CVD events and 307 subjects experienced all-cause death. The METS-VF quartile (Quartile 4 versus 1) was significantly related to CVD events [adjusted HRs and 95% CIs: 5.75 (2.67-12.42), 2.80 (1.76-4.48), and 3.31 (1.28-8.54) for subjects with normal glucose tolerance, prediabetes and diabetes, respectively] and all-cause mortality [adjusted HRs and 95% CIs: 2.80 (1.43-5.49), 4.15 (2.45-7.01), and 4.03 (1.72-9.42), respectively]. Restricted cubic spline suggested a dose-response association of METS-VF with the risk of CVD events and all-cause mortality. The area under curve for CVD events and all-cause mortality was higher for METS-VF than for the other obesity and IR indexes in subjects with different glucose tolerance statuses.

CONCLUSIONS

The METS-VF was associated with an increased risk of CVD events and all-cause mortality and could be used as a predictive index of the risk of CVD events and all-cause mortality among populations with different glucose tolerance statuses.

Prevalence of overweight and obesity among Iranian population: a systematic review and meta-analysis

BACKGROUND

Obesity is a major risk factor for chronic diseases. Politicians and practitioners should be aware of the dramatic increase in obesity and its subsequent complications to prevent associated health risks. This systematic review aimed to provide better insight into the prevalence of overweight and obesity in the Iranian population.

METHOD

An evaluation was conducted on all published observational studies from both national (SID, Irandoc, Iranmedex) and international (Web of Knowledge, PubMed, Scopus) sources, which reported the prevalence of overweight/obesity among normal population samples, between January 2012 and December 2021.

RESULT

A total of 152 eligible studies were included in this meta-analysis. Of the 152 selected studies, 74 reported the prevalence of overweight/obesity in patients aged ≤ 18 years, and 61 studies in adults. In the rest of the articles (17 studies), the results were reported for a combination of these age groups. The prevalence of overweight and obesity in Iran was estimated at 20.1 (95% CI 17.92-22.30) and 13.44 (95% CI 11.76-15.22), respectively. This percentage (95% CI) was 11.71 (10.98-12.46) for overweight and 8.08 (7.02-9.22) for obesity in those aged ≤ 18 years, and 35.26 (32.61-37.99) for overweight and 21.38 (19.61-23.20) for obesity in those aged > 18 years. The overall prevalence of overweight and obesity in the entire population was 35.09% (95% CI 31.31-38.98).

CONCLUSION

As obesity is on the rise in Iran, we should seek both weight loss strategies and ways to control comorbidities associated with high BMI.

Association of Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet and metabolically unhealthy overweight/obesity phenotypes among Iranian women: a cross sectional study

PURPOSE

Paradoxes have been found in obesity, including individuals with metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUHO), and diet may be one of the reasons for the creation of these metabolic phenotypes. Hence, the purpose of the present study was to investigate the association of the Mediterranean-DASH intervention for neurodegenerative delay (MIND) diet with metabolically unhealthy overweight/obesity (MUHOW/O) phenotypes.

METHODS

In this cross-sectional study, 229 overweight and obese women (body mass index (BMI) ≥ 25 kg/m2) aged 18-48 years were examined. Anthropometric measures and biochemical parameters were collected from all participants. The body composition of each participant was assessed using a bioelectrical impedance analyzer (BIA). The MIND diet score was determined based on 15 components using a valid and reliable food frequency questionnaire (FFQ) containing 147 items. Karelis criteria was used to determine metabolically healthy/unhealthy phenotype (MH/MUH).

RESULTS

Among the participants, 72.5% of individuals were identified as MUH and 27.5% as MH, with a mean ± standard deviation (SD) age of 36.16 (8.33) years. The results of our analysis showed that after controlling for age, energy intake, BMI, and physical activity, there was no significant association observed between overweight/obesity phenotypes with tertile 2 (T2) (OR: 2.01, 95% CI: 0.86-4.17, P-value = 0.10), T3 (OR: 1.89, 95% CI: 0.86-4.17, P-value = 0.11) of MIND score, and only the odds of MUH relative to MH with a marginal significant decreasing trend was observed from the second to the third tertile (1.89 vs. 2.01) (P - trend = 0.06). Also, after additional adjustment for marital status, the nonsignificant association between overweight/obesity phenotypes with tertile 2 (T2) (OR: 2.13, 95% CI: 0.89-5.10, P-value = 0.08), T3 (OR: 1.87, 95% CI: 0.83-4.23, P-value = 0.12) of MIND score remained, and the odds of MUH relative to MH with a significant decreasing trend was observed with increasing tertiles (P-trend = 0.04).

CONCLUSIONS

In conclusion, no significant associations were found between adherence to MIND diet with MUH, and only a significant downward trend in the odds of MUH was observed with increasing tertiles. We suggest further studies in this field.

The association between metabolic equivalent and visceral adiposity index among children and adolescents: Ten-cycle cross-sectional study on NHANES (1999-2018)

Metabolic disorder is globally prevalent in children and adolescents, and physical activity may have a protective role against metabolic disorder. However, the association between metabolic equivalent (MET) and visceral adiposity index (VAI) among children and adolescents remains unclear. This study aimed to address this concern. Data were retrieved from the National Health and Nutrition Examination Survey (NHANES), which used the Global Physical Activity Questionnaire to assess the physical activity levels. VAI was calculated according to body mass index (BMI), waist circumference (WC), triglyceride (TG), and high-density lipoprotein (HDL). Linear regression was adopted to assess the association between MET and VAI. Restricted cubic spline regression was used to further explore the nonlinear relationship, Interaction effect analysis was conducted to identify whether the sample characteristic could modify the effect of MET on VAI. After data cleansing, a total of 3402 participants aged <18 years were enrolled. In the fully adjusted linear regression model, the β for VAI was 0.01 (95% confidence interval [CI]: -0.08, 0.09) for the second tertile and -0.11 (95% CI: -0.20, -0.03) for the third tertile. A linear downward trend was found in the restricted cubic spline regression (overall P < .05). Interaction effect analysis revealed no significant effects of age, gender, race, income poverty ratio, and insurance (all P for interaction >0.05). High physical activity intensity is associated with decreased VAI scores in children and adolescents.

Effects of potential risk factors on the development of cardiometabolic multimorbidity and mortality among the elders in China

Objectives

To examine the impact of demographic, socioeconomic, and behavioral factors on the development of cardiometabolic multimorbidity and mortality in Chinese elders.

Methods

Data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) 2002–2018 was used in the study. Cardiometabolic multimorbidity was defined as the presence of two or more cardiometabolic disorders, such as hypertension, diabetes, cardiovascular disease (CVD), heart disease, or stroke. Cox regression model and multi-state Markov model were developed to evaluate the association of the study factors with the progression of cardiometabolic conditions and mortality. The outcomes included three states (first cardiometabolic disease, cardiometabolic multimorbidity, and all-cause mortality) and five possible transitions among the three states.

Results

Of the 13,933 eligible individuals, 7,917 (56.8%) were female, and 9,540 (68.50%) were over 80 years old. 2,766 (19.9%) participants had their first cardiometabolic disease, 975 (7.0%) participants suffered from cardiometabolic multimorbidity, and 9,365 (67.2%) participants died. The progression to cardiometabolic multimorbidity was positively associated with being female (HR = 1.42; 95%CI, 1.10 − 1.85), living in the city (HR = 1.41; 95%CI, 1.04 − 1.93), overweight (HR = 1.43; 95%CI, 1.08 − 1.90), and obesity (HR = 1.75; 95% CI, 1.03 − 2.98). A higher risk for the first cardiometabolic disease was associated with being female (HR = 1.26; 95% CI, 1.15 − 1.39), higher socioeconomic status (SES, HR = 1.17; 95%CI, 1.07 − 1.28), lack of regular physical activity (HR = 1.13; 95%CI, 1.04 − 1.23), smoking (HR = 1.20; 95%CI, 1.08 − 1.33), ≤ 5 h sleep time (HR = 1.15; 95%CI, 1.02 − 1.30), overweight (HR = 1.48; 95% CI, 1.32 − 1.66), and obesity (HR = 1.34; 95%CI, 1.06 − 1.69). It also should be noted that not in marriage, lower SES and unhealthy behavioral patterns were risk factors for mortality.

Conclusion

This study emphasized the importance of lifestyle and SES in tackling the development of cardiometabolic conditions among Chinese elders and provided a reference for policy-makers to develop a tailored stage-specific intervention strategy.

Are abdominal obese metabolically healthy phenotype a benign condition? Protocol for a systematic review

Background:

The prevalence of obesity is increasing worldwide. Obesity is associated with severe health effects. Abdominal obesity has a strong association with metabolic dysfunction. A subgroup of people with central obesity has been identified without typical metabolic disorders associated with obesity that has been known metabolically healthy abdominal obese (MHAO). The purpose of this review is to evaluate the MHAO phenotype in the context of type 2 DM incidence, risk of cardiovascular diseases, and all-cause of mortality.

Methods:

This is a protocol of systematic review. We will search PubMed/MEDLINE, EMBASE, Web of Science, Cochrane Library, and ProQuest. Additional studies will be identified through manual searching of reference lists. Quantitative studies evaluating abdominal obesity phenotype outcomes in adults will be included. Primary results will be assaying abdominal obesity phenotype results, including DM2 incidence, cardiovascular disease risk, and all-cause mortality. Two reviewers will independently screen full-text articles and abstract data.

Statistical Analysis Used:

Potential conflicts will be resolved through discussion.

Results:

The study methodological quality (or bias) will be appraised using appropriate tools. If feasible, we will conduct a random-effects meta-analysis. The researchers will also assess the quality of the articles independently based on Newcastle-Ottawa scale.

Conclusions:

The results of this review will provide a useful reference for the effect of abdominal obesity on metabolic dysfunction and cardiovascular or all-cause mortality

The Association between Metabolically Healthy Obesity, Cardiovascular Disease, and All-Cause Mortality Risk in Asia: A Systematic Review and Meta-Analysis

We investigated the association among metabolically healthy obesity (MHO), cardiovascular disease (CVD)risk, and all-cause mortality in the Asian population. We searched databases from inception to 16 November, 2019 and pooled data using a random-effects model. Subgroup analysis was conducted according to the following comparison groups: MHNW (without overweight or underweight participants) and MHNO (non-obese, including overweight and underweight participants). Nineteen studies were included. The mean Newcastle-Ottawa Scale score was 7.8. Participants with MHO had a significantly higher CVD risk (odds ratio (OR) = 1.36, 95% confidence interval (CI) = 1.13-1.63) and significantly lower risk of all-cause mortality (OR = 0.88, 95% CI = 0.78-1.00) than the comparison group. Subgroup analyses revealed participants with MHO had a significantly higher CVD risk than MHNW participants (OR = 1.61; 95% CI = 1.24-2.08; I² = 73%), but there was no significant difference compared with MHNO participants (OR, 1.04; 95% CI, 0.80-1.36; I² = 68%). Participants with MHO had a significantly lower risk of all-cause mortality (OR = 0.83; 95% CI = 0.78-0.88; I² = 9%) than MHNO participants, but a borderline significantly higher risk of all-cause mortality than MHNW participants (OR = 1.30; 95% CI = 0.99-1.72; I² = 0%). The CVD risk and all-cause mortality of the MHO group changed depending on the control group. Thus, future studies should select control groups carefully.

The association of Dietary Approach to Stop Hypertension (DASH) diet with metabolic healthy and metabolic unhealthy obesity phenotypes

The current study aimed at investigating the association between Dietary Approach to Stop Hypertension (DASH) diet and odds of obesity phenotypes, is a cross sectional study conducted on 3218 Iranian overweight or obese participants (BMI >25 kg/m²), aged ≥20 years, who participated in the fourth phase (2009–2011) of the Tehran Lipid and Glucose Study. Using a valid and reliable food-frequency questionnaire, DASH diet scores between 8 and 40 points were determined. Obesity phenotypes including metabolic unhealthy obesity (MUHO) and metabolic healthy obesity (MHO) were defined using criteria of the Joint International statement(JIS) for metabolic syndrome. Multivariable logistic regression was used to determine the odds ratio (OR) for obesity phenotypes according to the tertiles of the DASH diet. Mean ± SD age of participants (43.5% male) was 39.2 ± 9.5 years and median (25–75 interquartile range) DASH diet score was 24 (21–27); percentages of MHO and MUHO subjects were 33.4 and 66.6%, respectively. In the multivariable adjusted model, after controlling for age, sex, BMI, physical activity, smoking status, socioeconomic status, and energy intake, participants in the highest tertile of DASH diet had lower odds of MUHO (OR:0.79;95%CI:0.64–0.98), in comparison to those in the lowest one (P for trend = 0.040). Our findings indicate that adherence to DASH diet may be favourable in prevention of metabolic abnormalities in overweight and obese individuals.

Abdominal obesity phenotypes and incident diabetes over 12 years of follow-up: The Tehran Lipid and glucose study

AIMS

To investigate future diabetes in different abdominal obesity phenotypes during 12 years of follow-up.

METHODS

For this population-based cohort, 7982 adults without diabetes including 3533 men and 4449 women, aged ≥20 years were selected from the Tehran Lipid and Glucose Study. Abdominal obesity was defined according to the national cutoffs for waist circumference (WC). Metabolic health was defined as having ≤1 metabolic abnormality based on Joint Interim Statement (JIS) criteria other than WC. Participants were classified into 4 groups of abdominal obesity phenotypes: Metabolically healthy non-abdominal obese (MHNAO), metabolically healthy abdominal obese (MHAO), metabolically unhealthy non-abdominal Obese (MUNAO), and metabolically unhealthy abdominal obese (MUAO).

RESULTS

In total, 1018 cases of incident diabetes occurred. Compared to the MHNAO phenotype, based on multivariate Cox regression models, diabetes risk was increased in all unhealthy phenotypes except the MUNAO phenotype in men. Regarding the association of the MHAO phenotype with incident diabetes, borderline statistical significance in men [HR 1.5 (95% CI: 1.0-2.36), p-value: 0.07] and statistical significance in women [HR 1.68 (95% CI: 1.08-2.6)] were detected.

CONCLUSIONS

In addition to unhealthy phenotypes except the MUNAO phenotype in men, the MHAO phenotype is also associated with incident diabetes, highlighting the importance of preventive strategies in this subgroup of abdominally obese subjects.

Overweight and Obesity: Findings from 20 Years of the Tehran Lipid and Glucose Study

CONTEXT

The prevalence of overweight and obesity are increasing worldwide and have frequently been associated with health risks. This review highlighted several studies regarding obesity, outlining contributions of over a span of almost two decades in the Tehran Lipid and Glucose Study (TLGS).

EVIDENCE ACQUISITION

A systematic review was undertaken to retrieve articles related to all aspects of obesity from the earliest available date up to January 30, 2017.

RESULTS

Prevalence of excess weight, including overweight and obesity were 20.8 and 63.6% among those aged below and above 20 years, respectively. TLGS found a high incidence of obesity with higher incidence in women among Tehranian adults; the cumulative incidence of obesity was 31.3, 38.1 and 23.4% for the whole population, women, and men, respectively. In children and adolescents, younger non-obese 7 - 9 years old, compared to 10 - 11 year olds are at greater risk of obesity. Prevalences of abdominal obesity in men and women were 52.8% and 44.4% respectively. Similar to generalized obesity, a high incidence of abdominal obesity was observed; the total cumulative incidence of abdominal obesity was 76.0% (83.6% for men and 70.9% for women). Metabolically healthy obese (MHO) and metabolically healthy abdominal obese (MHAO) are two important obesity phenotypes. People with these phenotypes have different risks for cardiovascular disease (CVD), type 2 diabetes (T2DM), and mortality. In the TLGS participants, MHO was found in 2% and 7.7% of the whole and obese population, respectively, whereas MHAO phenotype was reported in 12.4% and 23.5% of the whole and abdominal obese population. In these unstable conditions, during the long term follow up the metabolic risks developed in nearly half of the individuals. During a 12-year follow-up, incident CVD did not increase in the MHO phenotype compared to metabolically healthy normal weight (MHNW) individuals, but the risk of CVD events had increased in all metabolically unhealthy phenotypes. However in another report, over a 10-year follow-up, MHAO phenotype had an increased risk for CVD in comparison to the reference group, metabolically healthy non-abdominal obese (MHNAO) individuals.

CONCLUSIONS

The TLGS studies bridged the significant gap in knowledge regarding prevalence, incidence, trends, morbidities and mortalities for obesity among Iranian population.

Role of Physical Activity and Fitness in the Characterization and Prognosis of the Metabolically Healthy Obesity Phenotype: A Systematic Review and Meta-analysis

The aims of the present article are to systematically review and meta-analyze the existing evidence on: 1) differences in physical activity (PA), sedentary behavior (SB), cardiorespiratory fitness (CRF) and muscular strength (MST) between metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO); and 2) the prognosis of all-cause mortality and cardiovascular disease (CVD) mortality/morbidity in MHO individuals, compared with the best scenario possible, i.e., metabolically healthy normal-weight (MHNW), after adjusting for PA, SB, CRF or MST. Our systematic review identified 67 cross-sectional studies to address aim 1, and 11 longitudinal studies to address aim 2. The major findings and conclusions from the current meta-analysis are: 1) MHO individuals are more active, spend less time in SB, and have a higher level of CRF (yet no differences in MST) than MUO individuals, suggesting that their healthier metabolic profile could be at least partially due to these healthier lifestyle factors and attributes. 2) The meta-analysis of cohort studies which accounted for PA (N = 10 unique cohorts, 100% scored as high-quality) support the notion that MHO individuals have a 24-33% higher risk of all-cause mortality and CVD mortality/morbidity compared to MHNW individuals. This risk was borderline significant/non-significant, independent of the length of the follow-up and lower than that reported in previous meta-analyses in this topic including all type of studies, which could be indicating a modest reduction in the risk estimates as a consequence of accounting for PA. 3) Only one study has examined the role of CRF in the prognosis of MHO individuals. This study suggests that the differences in the risk of all-cause mortality and CVD mortality/morbidity between MHO and MHNW are largely explained by differences in CRF between these two phenotypes.

Metabolically healthy obesity, vitamin D, and all-cause and cardiometabolic mortality risk in NHANES III

BACKGROUND & AIMS

Previous studies assessing the prognosis of metabolically healthy obesity (MHO) have been limited by a lack of a harmonized definition of MHO phenotype. Furthermore, obesity is a risk factor for vitamin D deficiency and low vitamin D status has been associated with a higher risk of mortality; however, few studies have evaluated the joint association between vitamin D, metabolic health phenotype, and mortality risk. Using a harmonized definition, we investigated whether MHO is associated with subsequent all-cause and cardiometabolic mortality, and whether serum 25-hydroxyvitamin D [25(OH)D] modifies these associations.

METHODS

This study included participants aged ≥20 years from the Third National Health and Nutrition Examination Survey (NHANES III). MHO phenotype was defined as a combination of obesity (≥30 kg/m²) and zero component of metabolic syndrome. Multivariable Cox regression was used to assess the risk of mortality across metabolic phenotypes, and the joint association between metabolic phenotype and 25(OH)D. Fine and Gray regression was performed to account for competing risk events.

RESULTS

Among 11,333 participants, a total of 2980 deaths (937 cardiometabolic death outcomes) occurred during a median follow-up of 19.1 years. In the absence of any metabolic abnormality, obesity (MHO) was not associated with a higher risk of all-cause (hazard ratio [HR], 0.89 [95% CI, 0.52-1.51]) or cardiometabolic mortality (cause-specific HR, 1.21 [95% CI 0.33-4.46]). Similar results were obtained from competing risk analysis. No significant differences in average 25(OH)D levels were observed between MHO and non-MHO participants; however, there was a significant interaction between metabolic health phenotype and serum 25(OH)D in relation to cardiometabolic mortality such that levels of serum 25(OH)D < 50 nmol/L were associated with increased risk of cardiometabolic mortality, particularly in participants within the normal-weight and obese BMI ranges.

CONCLUSIONS

Our results support the hypothesis that MHO phenotype is a benign health condition. Vitamin D deficiency may exacerbate the risk of cardiometabolic death outcomes associated with metabolic dysfunction in normal weight and obese individuals. Further research is warranted to validate our findings.