The obesity paradox: understanding the effect of obesity on mortality among individuals with cardiovascular disease

Association of overweight and obesity with coronary risk factors and the presence of multivessel disease in patients with obstructive coronary artery disease - A nationwide registry study

Background

The growing prevalence of obesity is expected to increase the burden of coronary artery disease. This study examined the prevalence of overweight and obesity in patients with a first-time diagnosis of obstructive coronary artery disease in a contemporary population. The association of body-mass-index (BMI) with age, traditional risk factors, and the presence of multivessel disease were explored.

Methods and results

Using the Danish Nationwide registries, we identified 49,733 patients with a first-time diagnosis of obstructive coronary artery disease in the period 2012-2018. We investigated the association between BMI and coronary risk factors by multivariate logistic regression. Mean age was 65.8 ± 11.8 years, mean BMI was 27.5 kg/m2 ± 7.2, and 73.2 % were men. 66.3 % had a BMI ≥25 kg/m2 and 1.3 % were underweight. The prevalence of patients with BMI ≥25 kg/m2 decreased with increasing age and was 69 % in patients <50 year vs. 46.2 % in patients ≥80 years (p < 0.001). In all age groups, higher odds of BMI ≥25 kg/m2 were observed in males, former smokers, and patients with hypertension. In multivariate logistic regression, BMI ≥25 kg/m2 was not associated with presence of multivessel disease (p = 0.74).

Conclusion

In this large, nationwide study, 66.3 % of patients with first time diagnosis of obstructive coronary disease had BMI ≥25 kg/m2. Young patients had higher BMI and were more likely to be current smokers. Overweight or obesity was independently associated with the presence of diabetes and hypertension. BMI ≥25 kg/m2 was not independently associated with the presence of multivessel disease.

Does obesity predict morbidity and mortality amongst patients undergoing transfemoral amputations?

BACKGROUND

We investigated the role of obesity on morbidity and mortality in patients undergoing above knee amputation.

METHODS

Data of 4225 patients undergoing AKAs was extracted from NIS Database (2016-2019) for a retrospectively matched case-control study and were grouped into; Non-obese (N-Ob-BMI <29.9 kg/m2; n = 1413), class I/II obese (Ob-I/II-BMI: 30-39.9 kg/m2; n = 1413), and class III obese groups (Ob-IIIBMI > 40; n = 1399). Morbidity, mortality, length of stay, and hospital charges were analyzed.

RESULTS

Blood loss anemia (OR = 1.42; 95% CI = 1.19-1.64), superficial SSI (OR = 5.10; 95% CI = 1.4717.63) and acute kidney injury (AKI- OR = 1.42; 95% CI = 1.21-1.67) were higher in Ob-III patients. Mortality was 5.8%, 4.5%, and 6.4% in N-Ob, Ob-I/II and Ob-III patients (p < 0.001; Ob-I/II vs. Ob-III), respectively. Hospital LOS was 3 days higher in Ob-III (16.1 ± 18.0), comparatively resulting in $25,481 higher inpatient-hospital charge.

CONCLUSION

Patients in Ob-III group were noted to have increased morbidity, higher LOS, and inpatient-hospital cost.

Impact of Healthy Lifestyle Factors on Life Expectancy and Lifetime Health Care Expenditure: Nationwide Cohort Study

BACKGROUND

The association between lifestyle risk factors and the risk of mortality and chronic diseases has been established, while limited research has explored the impact of healthy lifestyle factors on lifetime health care expenditure using longitudinal individual data.

OBJECTIVE

We aimed to determine the individual and combined effects of 5 healthy lifestyle factors on life expectancy and lifetime health care expenditure in Taiwan.

METHODS

Using data from the National Health Interview Survey cohort, 5 healthy lifestyle behaviors were defined and analyzed: nonsmoking, avoiding excessive alcohol consumption, engaging in sufficient physical activity, ensuring sufficient fruit and vegetable intake, and maintaining a normal weight. We used a rolling extrapolation algorithm that incorporated inverse probability of treatment weighting to estimate the life expectancy and lifetime health care expenditure of the study populations with and without healthy lifestyle factors.

RESULTS

A total of 19,893 participants aged ≥30 (mean age 48.8, SD 13.4) years were included, with 3815 deaths recorded during a median follow-up period of 15.6 years. The life expectancy and per capita estimated lifetime health care expenditures for the overall study population were 35.32 years and US $58,560, respectively. Multivariable-adjusted hazard ratios for all-cause mortality in participants adhering to all 5 healthy lifestyle factors, compared with those adhering to none, were 0.37 (95% CI 0.27-0.49). We found significant increases in life expectancy for nonsmokers (2.31 years; 95% CI 0.04-5.13; P=.03), those with sufficient physical activity (1.85 years; 95% CI 0.25-4.34; P=.02), and those with adequate fruit and vegetable intake (3.25 years; 95% CI 1.29-6.81; P=.01). In addition, nonsmokers experienced a significant reduction in annual health care expenditure (-9.78%; 95% CI -46.53% to -1.45%; P=.03), as did individuals maintaining optimal body weight (-18.36%; 95% CI -29.66% to -8.57%; P=.01). Overall, participants adhering to all 5 healthy lifestyle behaviors exhibited a life gain of 7.13 years (95% CI 1.33-11.11; P=.02) compared with those adhering to one or none, with a life expectancy of 29.19 years (95% CI 25.45-33.62). Furthermore, individuals adopting all 5 healthy lifestyle factors experienced an average annual health care expenditure reduction of 28.12% (95% CI 4.43%-57.61%; P=.02) compared with those adopting one or none.

CONCLUSIONS

Adopting a healthy lifestyle is associated with a longer life expectancy and a reduction of health care expenditure in Taiwanese adults. This contributes to a more comprehensive understanding of the impact of healthy lifestyle factors on the overall health and economic burden.

Body mass index, waist circumference, and mortality in subjects older than 80 years: a Mendelian randomization study

BACKGROUND AND AIMS

Emerging evidence has raised an obesity paradox in observational studies of body mass index (BMI) and health among the oldest-old (aged ≥80 years), as an inverse relationship of BMI with mortality was reported. This study was to investigate the causal associations of BMI, waist circumference (WC), or both with mortality in the oldest-old people in China.

METHODS

A total of 5306 community-based oldest-old (mean age 90.6 years) were enrolled in the Chinese Longitudinal Healthy Longevity Survey (CLHLS) between 1998 and 2018. Genetic risk scores were constructed from 58 single-nucleotide polymorphisms (SNPs) associated with BMI and 49 SNPs associated with WC to subsequently derive causal estimates for Mendelian randomization (MR) models. One-sample linear MR along with non-linear MR analyses were performed to explore the associations of genetically predicted BMI, WC, and their joint effect with all-cause mortality, cardiovascular disease (CVD) mortality, and non-CVD mortality.

RESULTS

During 24 337 person-years of follow-up, 3766 deaths were documented. In observational analyses, higher BMI and WC were both associated with decreased mortality risk [hazard ratio (HR) 0.963, 95% confidence interval (CI) 0.955-0.971 for a 1-kg/m2 increment of BMI and HR 0.971 (95% CI 0.950-0.993) for each 5 cm increase of WC]. Linear MR models indicated that each 1 kg/m2 increase in genetically predicted BMI was monotonically associated with a 4.5% decrease in all-cause mortality risk [HR 0.955 (95% CI 0.928-0.983)]. Non-linear curves showed the lowest mortality risk at the BMI of around 28.0 kg/m2, suggesting that optimal BMI for the oldest-old may be around overweight or mild obesity. Positive monotonic causal associations were observed between WC and all-cause mortality [HR 1.108 (95% CI 1.036-1.185) per 5 cm increase], CVD mortality [HR 1.193 (95% CI 1.064-1.337)], and non-CVD mortality [HR 1.110 (95% CI 1.016-1.212)]. The joint effect analyses indicated that the lowest risk was observed among those with higher BMI and lower WC.

CONCLUSIONS

Among the oldest-old, opposite causal associations of BMI and WC with mortality were observed, and a body figure with higher BMI and lower WC could substantially decrease the mortality risk. Guidelines for the weight management should be cautiously designed and implemented among the oldest-old people, considering distinct roles of BMI and WC.

Deep learning model for the prediction of all-cause mortality among long term care people in China: a prospective cohort study

This study aimed to develop a deep learning model to predict the risk stratification of all-cause death for older people with disability, providing guidance for long-term care plans. Based on the government-led long-term care insurance program in a pilot city of China from 2017 and followed up to 2021, the study included 42,353 disabled adults aged over 65, with 25,071 assigned to the training set and 17,282 to the validation set. The administrative data (including baseline characteristics, underlying medical conditions, and all-cause mortality) were collected to develop a deep learning model by least absolute shrinkage and selection operator. After a median follow-up time of 14 months, 17,565 (41.5%) deaths were recorded. Thirty predictors were identified and included in the final models for disability-related deaths. Physical disability (mobility, incontinence, feeding), adverse events (pressure ulcers and falls from bed), and cancer were related to poor prognosis. A total of 10,127, 25,140 and 7086 individuals were classified into low-, medium-, and high-risk groups, with actual risk probabilities of death of 9.5%, 45.8%, and 85.5%, respectively. This deep learning model could facilitate the prevention of risk factors and provide guidance for long-term care model planning based on risk stratification.

Association of body mass index and waist circumference with long-term mortality risk in 10,370 coronary patients and potential modification by lifestyle and health determinants

BACKGROUND AND AIMS

Body adiposity is known to affect mortality risk in patients with coronary artery disease (CAD). We examined associations of body mass index (BMI) and waist circumference (WC) with long term mortality in Dutch CAD patients, and potential and effect modification of these associations by lifestyle and health determinants.

METHODS

10,370 CAD patients (mean age ∼65 y; 20% female; >80% on cardiovascular drugs) from the prospective Alpha Omega Cohort and Utrecht Cardiovascular Cohort-Secondary Manifestations of ARTerial disease study were included. Cox models were used to estimate categorical and continuous associations (using restricted cubic splines) of measured BMI and WC with all-cause and cardiovascular mortality risk, adjusting for age, sex, smoking, alcohol, physical activity and educational level. Analyses were repeated in subgroups of lifestyle factors (smoking, physical activity, diet quality), education and health determinants (diabetes, self-rated health).

RESULTS

During ∼10 years of follow-up (91,947 person-years), 3,553 deaths occurred, including 1,620 from cardiovascular disease. U-shaped relationships were found for BMI and mortality risk, with the lowest risk for overweight patients (BMI ∼27 kg/m2). For obesity (BMI ≥30), the HR for all-cause mortality was 1.31 (95% CI: 1.11, 1.41) in male patients and 1.10 (95% CI: 0.92, 1.30) in female patients, compared to BMI 25-30 kg/m2. WC was also non-linearly associated with mortality, and HRs were 1.18 (95%CI:1.06, 1.30) in males and 1.31 (95%CI:1.05, 1.64) in females for the highest vs. middle category of WC. Results for cardiovascular mortality were mostly in line with the results for all-cause mortality. U-shaped associations were found in most subgroups, associations were moderately modified by physical activity, smoking and educational level.

CONCLUSIONS

CAD patients with obesity and a large WC were at increased risk of long-term CVD and all-cause mortality, while mildly overweight patients had the lowest risk. These associations were consistent across subgroups of patients with different lifestyles and health status.

Athletic Injury Research: Frameworks, Models and the Need for Causal Knowledge

Within applied sports science and medicine research, many challenges hinder the establishment and detailed understanding of athletic injury causality as well as the development and implementation of appropriate athletic injury prevention strategies. Applied research efforts are faced with a lack of variable control, while the capacity to compensate for this lack of control through the application of randomised controlled trials is often confronted by a number of obstacles relating to ethical or practical constraints. Such difficulties have led to a large reliance upon observational research to guide applied practice in this area. However, the reliance upon observational research, in conjunction with the general absence of supporting causal inference tools and structures, has hindered both the acquisition of causal knowledge in relation to athletic injury and the development of appropriate injury prevention strategies. Indeed, much of athletic injury research functions on a (causal) model-blind observational approach primarily driven by the existence and availability of various technologies and data, with little regard for how these technologies and their associated metrics can conceptually relate to athletic injury causality and mechanisms. In this article, a potential solution to these issues is proposed and a new model for investigating athletic injury aetiology and mechanisms, and for developing and evaluating injury prevention strategies, is presented. This solution is centred on the construction and utilisation of various causal diagrams, such as frameworks, models and causal directed acyclic graphs (DAGs), to help guide athletic injury research and prevention efforts. This approach will alleviate many of the challenges facing athletic injury research by facilitating the investigation of specific causal links, mechanisms and assumptions with appropriate scientific methods, aiding the translation of lab-based research into the applied sporting world, and guiding causal inferences from applied research efforts by establishing appropriate supporting causal structures. Further, this approach will also help guide the development and adoption of both relevant metrics (and technologies) and injury prevention strategies, as well as encourage the construction of appropriate theoretical and conceptual foundations prior to the commencement of applied injury research studies. This will help minimise the risk of resource wastage, data fishing, p-hacking and hypothesising after the results are known (HARK-ing) in athletic injury research.

Investigation of the therapeutic effect of Hedan tablets on high-fat diet-induced obesity in rats by GC-MS technology and 16S ribosomal RNA gene sequencing

Obesity is a persistent metabolic condition resulting from the excessive accumulation or abnormal distribution of body fat. This study aimed to establish an experimental rat model of obesity. The efficacy of treating obesity with Hedan tablets (HDT) was assessed by monitoring changes in weight, blood lipid levels, analyzing inflammatory factors, evaluating organ indices, and observing liver tissue pathology. Furthermore, we utilized 16S ribosomal RNA gene sequencing technology to explore changes in intestinal flora. In addition, GC-MS was used to measure fecal short-chain fatty acid (SCFA) content. The onset of obesity led to a significant decrease in the relative abundance of beneficial bacteria. Conversely, the administration of HDT demonstrated a substantial ability to increase the relative abundance of beneficial bacteria. Obesity resulted in a noteworthy reduction in total SCFAs, a trend significantly reversed in the HDT group. Through correlation analysis, it was determined that HDT mitigated the inflammatory response and improved blood lipid levels by augmenting the abundance of Lactobacillus, Limosilactobacillus, Ruminococcus, and Enterococcus. These particular intestinal flora were identified as regulators of SCFA metabolism, thereby ameliorating metabolic abnormalities associated with obesity. Moreover, HDT intervention elevated the overall fecal concentration of SCFAs, thereby improving metabolic disorders induced by obesity. The anti-obesity effects of HDT are likely attributable to their capacity to influence the composition of intestinal flora and boost SCFA levels in the intestine.

Obesity Paradox in Patients with Acute Coronary Syndrome: Is Malnutrition the Answer?

BACKGROUND

Obesity paradox has been reported in patients with cardiovascular disease, showing an inverse association between obesity as defined by BMI (in kg/m2) and prognosis. Nutritional status is associated with systemic inflammatory response and affects cardiovascular disease outcomes.

OBJECTIVES

This study sought to examine the influence of obesity and malnutrition on the prognosis of patients with acute coronary syndrome (ACS).

METHODS

This study included consecutive patients diagnosed with ACS and underwent coronary angiogram between January 2009 and February 2023. At baseline, patients were categorized according to their BMI as follows: underweight (<18), normal weight (18-24.9), overweight (25.0-29.9), and obese (>30.0). We assessed the nutritional status by Prognostic Nutritional Index (PNI). Malnutrition was defined as a PNI value of <38.

RESULTS

Of the 21,651 patients with ACS, 582 (2.7%) deaths from any cause were observed over 28.7 months. Compared with the patient's state of normal weight, overweight, and obesity were associated with decreased risk of all-cause mortality. Malnutrition was independently associated with poor survival (hazards ratio: 2.64; 95% CI: 2.24, 3.12; P < 0.001). In malnourished patients, overweight and obesity showed a 39% and 72% reduction in the incidence of all-cause mortality, respectively. However, in nourished patients, no significant reduction in the incidence of all-cause mortality was observed (all P > 0.05).

CONCLUSIONS

Obesity paradox appears to occur in patients with ACS. Malnutrition may be a significant independent risk factor for prognosis in patients with ACS. The obesity paradox is influenced by the status of malnutrition.

Differential Participation, a Potential Cause of Spurious Associations in Observational Cohorts in Environmental Epidemiology

Differential participation in observational cohorts may lead to biased or even reversed estimates. In this article, we describe the potential for differential participation in cohorts studying the etiologic effects of long-term environmental exposures. Such cohorts are prone to differential participation because only those who survived until the start of follow-up and were healthy enough before enrollment will participate, and many environmental exposures are prevalent in the target population and connected to participation via factors such as geography or frailty. The relatively modest effect sizes of most environmental exposures also make any bias induced by differential participation particularly important to understand and account for. We discuss key points to consider for evaluating differential participation and use causal graphs to describe two example mechanisms through which differential participation can occur in health studies of long-term environmental exposures. We use a real-life example, the Canadian Community Health Survey cohort, to illustrate the non-negligible bias due to differential participation. We also demonstrate that implementing a simple washout period may reduce the bias and recover more valid results if the effect of interest is constant over time. Furthermore, we implement simulation scenarios to confirm the plausibility of the two mechanisms causing bias and the utility of the washout method. Since the existence of differential participation can be difficult to diagnose with traditional analytical approaches that calculate a summary effect estimate, we encourage researchers to systematically investigate the presence of time-varying effect estimates and potential spurious patterns (especially in initial periods in the setting of differential participation).

Association of systemic inflammation with the obesity paradox in cancer: results from multi-cohort studies

AIMS

This study aimed to explore whether the obesity paradox exists in overall and specific cancers and to investigate the role of systemic inflammation in the obesity paradox.

METHODS

The Cox proportional hazard model was used to explore the relationship between body mass index (BMI) and all-cause mortality. The mediated effect was used to investigate the proportion of systemic inflammation mediating the relationship between BMI and cancer survival risk.

RESULTS

The survival probability showed a step-like increase with an increase in BMI regardless of pathological stage. Approximately 10.8%-24.0% of the overall association between BMI and all-cause mortality in cancer was mediated by inflammation. In the internal validation, we found evidence of the obesity paradox in all body composition obtained using BIA, with inflammation remaining an important mediating factor. Furthermore, we also validated the existence of the obesity paradox of cancer in NHANES. Systemic inflammation remains an important factor in mediating the association between BMI and prognosis in cancer patients.

CONCLUSIONS

The obesity paradox is prevalent in most cancers, except for hepatic biliary cancer and breast cancer. Inflammation may be one of the true features of the obesity paradox in cancer.

BMI trajectory in adulthood in relation to all-cause and cause-specific mortality: A retrospective cohort study in Taiwan

A dynamic change of weight over time has been known as an important factor that impacts mortality risk. The aims of this study were to identify the heterogeneity of BMI trajectory groups and to examine the association of the trajectories of BMI and all-cause and cause-specific mortality. The data for this study were obtained from a large prospective cohort study in Taiwan between 1998 and 2019 that was linked to the National Death Registry for death information. The participants were stratified into four groups by age and gender; self-reported demographics and measured BMI data were used. We used group-based trajectory analysis to identify the distinct trajectories of changes in BMI. A Cox proportional hazards model was used to assess the hazard ratio (HR) of all-cause and cause-specific mortality risk. Data were analyzed in April 2020 and included 89,886 participants. Four trajectory groups were identified by the pattern of BMI change over time. Our study shows that different trajectories were associated with mortality. Our findings suggest that the mortality risk differs in each trajectory group and in each age and gender stratification. It appears that obesity is a protective factor in cancer-related mortality in females but not in males in group of old age participants; low-normal weight is a risk factor in respiratory-related mortality in all participants. Our findings can be used to suggest the appropriate BMI in each age and gender groups and thereby earlier health interventions can be taken to avoid mortality.

Collider and reporting biases involved in the analyses of cause of death associations in death certificates: an illustration with cancer and suicide

BACKGROUND

Mortality data obtained from death certificates have been studied to explore causal associations between diseases. However, these analyses are subject to collider and reporting biases (selection and information biases, respectively). We aimed to assess to what extent associations of causes of death estimated from individual mortality data can be extrapolated as associations of disease states in the general population.

METHODS

We used a multistate model to generate populations of individuals and simulate their health states up to death from national health statistics and artificially replicate collider bias. Associations between health states can then be estimated from such simulated deaths by logistic regression and the magnitude of collider bias assessed. Reporting bias can be approximated by comparing the estimates obtained from the observed death certificates (subject to collider and reporting biases) with those obtained from the simulated deaths (subject to collider bias only). As an illustrative example, we estimated the association between cancer and suicide in French death certificates and found that cancer was negatively associated with suicide. Collider bias, due to conditioning inclusion in the study population on death, increasingly downwarded the associations with cancer site lethality. Reporting bias was much stronger than collider bias and depended on the cancer site, but not prognosis.

RESULTS

The magnitude of the biases ranged from 1.7 to 9.3 for collider bias, and from 4.7 to 64 for reporting bias.

CONCLUSIONS

These results argue for an assessment of the magnitude of both collider and reporting biases before performing analyses of cause of death associations exclusively from mortality data. If these biases cannot be corrected, results from these analyses should not be extrapolated to the general population.

Crossing Birth-Weight-Specific Mortality Curves: How a Puzzling Clinical Observation Led to an Important Advance in Epidemiologic Methods

Throughout the second half of the 20th century, clinicians noted that although African-American neonates were more likely than White neonates to weigh less than 2,500 g at birth (low birth weight), among low-birth-weight infants African Americans were more likely than Whites to survive. However, when born at normal weight, African-American infants were substantially less likely to survive. The observation generated much physiological speculation, and several clever mathematical manipulations were devised to "uncross the mortality curves." With the development and dissemination of directed acyclic graphs in the early 2000s, methodologists focusing on perinatal epidemiology showed graphically, in an early use of directed acyclic graphs, that birth weight was a "collider" and that controlling for birth weight, whether by regression, stratification, or restriction, introduced confounding of the race-mortality association by all unmeasured common causes of birth weight and mortality. These investigations showed that the crossing curves could be explained as an artifact of a conceptually flawed analysis. These results have applicability beyond perinatal epidemiology, including applicability to the "obesity paradox."

The Influence of Obesity on Outcomes with Immune Checkpoint Blockade: Clinical Evidence and Potential Biological Mechanisms

Immune checkpoint blockade (ICB) is a mainstay of treatment for advanced cancer, yet tumor response and host toxicity are heterogenous in those patients who receive ICB. There is growing interest in understanding how host factors interact with tumor intrinsic properties and the tumor microenvironment to influence the therapeutic index with ICB. Obesity, defined by body mass index, is a host factor associated with improved outcomes in select cancers when treated with ICB. While the biological mechanism for this obesity paradox is not fully understood, pre-clinical and translational studies suggest obesity may potentially impact tumor metabolism, inflammation, and angiogenesis. Herein, we summarize clinical studies that support an obesity paradox with ICB, explore potential biological mechanisms that may account for the obesity paradox, and address methodological challenges to consider when studying obesity and treatment outcomes.

Body Mass Index and All-Cause and Cardiovascular Mortality in United States Adults With and Without Atherosclerotic Cardiovascular Disease: Findings from the National Health Interview Survey

In a nationally representative population-based study of US adults, the authors sought to examine the association between body mass index (BMI) and all-cause and cardiovascular disease (CVD) mortality in a nationally representative sample of adults with and without atherosclerotic cardiovascular disease (ASCVD), and further stratified by age, sex, and race/ethnicity. The study used data from 2006 to 2015 National Health Interview Survey and categorized participants into the following BMI categories: normal weight (20-24.9), overweight (25-29.9), obesity class 1 (30-34.9), obesity class 2 (35-39.9), and obesity class 3 (≥40 kg/m2). Multivariable Cox proportional hazards models were used to assess the risk of all-cause and CVD mortality across successively increasing BMI categories overall, and by sociodemographic subgroups. A total of 210,923 individuals were included in the final analysis. In the population without ASCVD, the risk of all-cause and CVD mortality was lower in overweight and higher in obesity classes 2 and 3, compared with normal weight, with the highest risk observed in the young adult (age 18-39) population. Elderly adults (65 and above) and populations with ASCVD exhibited a BMI-mortality paradox. In addition, Hispanic individuals did not show a relationship between BMI and mortality compared with non-Hispanic White and Black adults. In conclusion, being overweight was associated with decreased risk, whereas obesity class 3 was consistently associated with increased risk of all-cause and CVD mortality in adults without ASCVD, particularly young adults. BMI-mortality paradox was noted in ASCVD, elderly, and non-Hispanic adults.

Premature Death, Underlying Reasons, and Preventive Experiences in Iran: A Narrative Review

Premature mortality (PM) has emerged as a global health challenge. This is of eminent importance in low- and middle-income countries, where nearly three fourths of the deaths occur. The concerning issue is the early occurrence of fatal events in productive age. Fatal events before the age of 70 are called PM, which mainly result from cardiovascular diseases (CVDs). Iran as a middle- income country greatly suffers from the cardiovascular burden, which accounts for almost 50% of all PM. Despite substantial success in reducing mortality due to communicable diseases across different age ranges, urbanization and pervasiveness of cardiovascular risk factors have increased the death rate in adults in recent years. Undoubtedly, such lifestyles have imposed heavy costs on the healthcare system; it is possible that PM reduction, as one of the fundamental elements of sustainable development goals defined by the World Health Organization (WHO), would not be reached by the due date. Recently, researchers have introduced a cost-effective fixed-dose drug combination, the so-called polypill, in order to attenuate the detrimental effects of hypertension and hyperlipidemia, as two strong cardiovascular risk factors. PolyIran and PolyIran-Liver studies are two pivotal clinical trials that revealed the feasibility of primary and secondary prevention of premature cardiovascular mortality, both in an urban and a rural population. In the present narrative review, we tried to present a comprehensive appraisal on PM status, its underlying reasons, and the impact of polypill strategy on PM prevention in Iran.

All-Cause, Cardiovascular, and Stroke Mortality Among Foreign-Born Versus US-Born Individuals of African Ancestry

Background Little is known about the effect of region of origin on all-cause mortality, cardiovascular mortality, and stroke mortality among Black individuals. We examined associations between nativity and mortality (all-cause, cardiovascular, and stroke) in Black individuals in the United States. Methods and Results Using the National Health Interview Service 2000 to 2014 data and mortality-linked files through 2015, we identified participants aged 25 to 74 years who self-identified as Black (n=64 717). Using a Cox regression model, we examined the association between nativity and all-cause, cardiovascular, and stroke mortality. We recorded 4329 deaths (205 stroke and 932 cardiovascular deaths). In the model adjusted for age and sex, compared with US-born Black individuals, all-cause (hazard ratio [HR], 0.44 [95% CI, 0.37-0.53]) and cardiovascular mortality (HR, 0.66 [95% CI, 0.44-0.87]) rates were lower among Black individuals born in the Caribbean, South America, and Central America, but stroke mortality rates were similar (HR, 1.01 [95% CI, 0.52-1.94]). African-born Black individuals had lower all-cause mortality (HR, 0.43 [95% CI, 0.27-0.69]) and lower cardiovascular mortality (HR, 0.42 [95% CI, 0.18-0.98]) but comparable stroke mortality (HR, 0.48 [95% CI, 0.11-2.05]). When the model was further adjusted for education, income, smoking, body mass index, hypertension, and diabetes, the difference in mortality between foreign-born Black individuals and US-born Black individuals was no longer significant. Time since migration did not significantly affect mortality outcomes among foreign-born Black individuals. Conclusions In the United States, foreign-born Black individuals had lower all-cause mortality, a difference that was observed in recent and well-established immigrants. Foreign-born Black people had age- and sex-adjusted lower cardiovascular mortality than US-born Black people.

Third dose mRNA vaccination against SARS-CoV-2 reduces medical complaints seen in primary care: a matched cohort study

BACKGROUND

SARS-CoV-2 mRNA vaccination has been associated with both side effects and a reduction in COVID-related complaints due to the decrease in COVID-19 incidence. We aimed to investigate if individuals who received three doses of SARS-CoV-2 mRNA vaccines had a lower incidence of (a) medical complaints and (b) COVID-19-related medical complaints, both as seen in primary care, when compared to individuals who received two doses.

METHODS

We conducted a daily longitudinal exact one-to-one matching study based on a set of covariates. We obtained a matched sample of 315,650 individuals aged 18-70 years who received the 3rd dose at 20-30 weeks after the 2nd dose and an equally large control group who did not. Outcome variables were diagnostic codes as reported by general practitioners or emergency wards, both alone and in combination with diagnostic codes of confirmed COVID-19. For each outcome, we estimated cumulative incidence functions with hospitalization and death as competing events.

RESULTS

We found that the number of medical complaints was lower in individuals aged 18-44 years who received three doses compared to those who received two doses. The differences in estimates per 100,000 vaccinated were as follows: fatigue 458 less (95% confidence interval: 355-539), musculoskeletal pain 171 less (48-292), cough 118 less (65-173), heart palpitations 57 less (22-98), shortness of breath 118 less (81-149), and brain fog 31 less (8-55). We also found a lower number of COVID-19-related medical complaints: per 100,000 individuals aged 18-44 years vaccinated with three doses, there were 102 (76-125) fewer individuals with fatigue, 32 (18-45) fewer with musculoskeletal pain, 30 (14-45) fewer with cough, and 36 (22-48) fewer with shortness of breath. There were no or fewer differences in heart palpitations (8 (1-16)) or brain fog (0 (- 1-8)). We observed similar results, though more uncertain, for individuals aged 45-70 years, both for medical complaints and for medical complaints that were COVID-19 related.

CONCLUSIONS

Our findings suggest that a 3rd dose of SARS-CoV-2 mRNA vaccine administered 20-30 weeks after the 2nd dose may reduce the incidence of medical complaints. It may also reduce the COVID-19-related burden on primary healthcare services.

Associations of changes in physical activity and diet with incident obesity and changes in adiposity: Longitudinal findings from the UK Biobank

We examined the association of changes in physical activity and diet with obesity development and changes in body fat percentage, body mass index, and waist circumference. 31,344 adults without obesity at baseline (age = 56.0 ± 7.5 years; female = 49.1%) from the UK Biobank were included. Physical activity was categorised based on public health guidelines as: inactive; insufficient; and sufficient. Diet category was assigned based on an established composited score that included consumption of fruits, vegetables, fish, red meat (unprocessed), and processed meat. Diet was categorised as: poor; reasonable; and good. Physical activity and diet changes were categorised based on changes in category: worsened; stable; increased (physical activity)/improved (diet). During a mean follow up of 6.8 (SD = ±2.3) years, 1354 (4.3%) participants developed obesity. Compared to stable physical activity-diet, increasing physical activity was associated with the lowest obesity odds, across diet changes (e.g., OR [95%CI]: diet worsened (0.89 [0.69, 1.15]); diet improved (0.65 [0.48, 0.89])). Increasing physical activity with improved diet was associated with the largest difference in body fat percentage (β:-0.62 [-0.82, -0.41]), body mass index (-0.37 [-0.47, -0.28]), and waist circumference (-1.21 [-1.63, -0.79]). Excluding adults with a history of smoking, or major illness, lowered obesity odds among participants with increased physical activity by an additional 11%-21%. In those who decreased physical activity obesity was attenuated when combined with diet improvement. Improvements in physical activity or diet mutually attenuated the deleterious associations of the other behaviour's deterioration. In most analyses, increases in physical activity conferred consistent positive associations against the development of obesity, across dietary change groups.

Interaction Between Obesity and Hypertension on Arteriosclerosis in Chinese Urban Adults: A Population-Based Cross-Sectional Study

This study recruited 9,830 participants to identify whether the interaction between obesity and hypertension affects the occurrence of arteriosclerosis in Chinese adults. Brachial-ankle pulse wave velocity (baPWV) was measured to diagnose arteriosclerosis. Unconditional logistic regression was used for multiplicative interaction. The additive interaction was represented by relative excess risk due to interaction (RERI), attributable proportion (AP), and synergy (S). Hypertension was an independent risk factor for baPWV (p < .01), but obesity was not (p = .08). The interaction between obesity and hypertension on arteriosclerosis was not multiplicative (adjusted odds ratio = 0.89 (0.79-1.01), p = .07), but a negative additive interaction (RERI = -4.33, AP = -2.91, S = 0.10; p < .01) exists. Therefore, obesity may reduce the risk of arteriosclerosis caused by hypertension when hypertension and obesity coexist, especially in women and middle-aged people, which supports the obesity paradox.

Collider bias and the obesity paradox

Obesity paradoxes have been reported in many diseases to date. As the wording "paradox" indicates, our intuition rejects the hypothesis that obese people have a better life expectancy or fewer cardiovascular events. One of the most plausible explanations for the obesity paradox is collider bias, but controversy about this is ongoing. If the findings of the original research are affected by collider bias, meta-analyses of that research will also be affected by the same bias. It is to be hoped that the use of appropriate analytical techniques will enable the true nature of the obesity bias to become clear.

Causal evidence in health decision making: methodological approaches of causal inference and health decision science

Objectives

Public health decision making is a complex process based on thorough and comprehensive health technology assessments involving the comparison of different strategies, values and tradeoffs under uncertainty. This process must be based on best available evidence and plausible assumptions. Causal inference and health decision science are two methodological approaches providing information to help guide decision making in health care. Both approaches are quantitative methods that use statistical and modeling techniques and simplifying assumptions to mimic the complexity of the real world. We intend to review and lay out both disciplines with their aims, strengths and limitations based on a combination of textbook knowledge and expert experience.

Methods

To help understanding and differentiating the methodological approaches of causal inference and health decision science, we reviewed both methods with the focus on aims, research questions, methods, assumptions, limitations and challenges, and software. For each methodological approach, we established a group of four experts from our own working group to carefully review and summarize each method, followed by structured discussion rounds and written reviews, in which the experts from all disciplines including HTA and medicine were involved. The entire expert group discussed objectives, strengths and limitations of both methodological areas, and potential synergies. Finally, we derived recommendations for further research and provide a brief outlook on future trends.

Results

Causal inference methods aim for drawing causal conclusions from empirical data on the relationship of pre-specified interventions on a specific target outcome and apply a counterfactual framework and statistical techniques to derive causal effects of exposures or interventions from these data. Causal inference is based on a causal diagram, more specifically, a directed acyclic graph (DAG), which encodes the assumptions regarding the causal relations between variables. Depending on the type of confounding and selection bias, traditional statistical methods or more complex g-methods are needed to derive valid causal effects. Besides the correct specification of the DAG and the statistical model, assumptions such as consistency, positivity, and exchangeability must be checked when aiming at causal inference. Health decision science aims for guiding policy decision making regarding health interventions considering and balancing multiple competing objectives of a decision based on data from multiple sources and studies, for example prevalence studies, clinical trials and long-term observational routine effectiveness studies, and studies on preferences and costs. It involves decision analysis, a systematic, explicit and quantitative framework to guide decisions under uncertainty. Decision analyses are based on decision-analytic models to mimic the course of disease as well as aspects and consequences of the intervention in order to quantitatively optimize the decision. Depending on the type of decision problem, decision trees, state-transition models, discrete event simulation models, dynamic transmission models, or other model types are applied. Models must be validated against observed data, and comprehensive sensitivity analyses must be performed to assess uncertainty. Besides the appropriate choice of the model type and the valid specification of the model structure, it must be checked if input parameters of effects can be interpreted as causal parameters in the model. Otherwise results will be biased.

Conclusions

Both causal inference and health decision science aim for providing best causal evidence for informed health decision making. The strengths and limitations of both methods differ and a good understanding of both methods is essential for correct application but also for correct interpretation of findings from the described methods. Importantly, decision-analytic modeling should be combined with causal inference when developing guidance and recommendations regarding decisions on health care interventions.

Cohort Study and Bias Analysis of the Obesity Paradox Across Stages of Chronic Kidney Disease

OBJECTIVE

In advanced chronic kidney disease (CKD), patients with obesity often have better outcomes than patients without obesity, often called the 'obesity paradox'. Yet, in CKD, the prevalence of inflammation increases as CKD progresses. Although a potential confounder, inflammation may be left unaccounted in obesity-mortality studies. We examined the associations of body mass index (BMI) with all-cause and cause-specific mortality across CKD stages, with consideration for uncontrolled confounding due to unmeasured inflammation.

METHODS

We investigated 2,703,512 patients with BMI data between 2004 and 2006. We used Cox models to examine the associations of BMI with all-cause, cardiovascular, and cancer mortality, (ref: BMI 25-<30 kg/m2), adjusted for clinical characteristics and stratified by CKD stages. To address uncontrolled confounding, we performed bias analysis using a weighted probabilistic model of inflammation given the observed data applied to weighted Cox models.

RESULTS

The cohort included 5% females and 14% African Americans. In adjusted analyses, the associations of the BMI with all-cause and cardiovascular mortality showed a reverse J-shape, where a higher BMI (>40 kg/m2) was associated with a higher risk. Conversely, a lower mortality risk was observed with a BMI 30-<35 kg/m2 across all CKD stages and for BMI >40 kg/m2 in CKD stage 4/5. Cancer mortality analyses showed an inverse relationship. Bias analysis for uncontrolled confounding suggested that independent of inflammation, the obesity paradox was present.

CONCLUSION

We observed the presence of the obesity paradox in this study. This association was consistent in advanced CKD and in our bias analysis, suggesting that inflammation may not fully explain the observed BMI-mortality associations including in patients with CKD.

The obesity paradox is mostly driven by decreased noncardiovascular disease mortality in the oldest old in China: a 20-year prospective cohort study

National and international recommendations of healthy body mass index (BMI) are primarily based on evidence in young and middle-aged populations, with an insufficient representation of the oldest old (aged ≥80 years). Here, we report associations between BMI and mortality risk in 27,026 community-dwelling oldest old (mean age, 92.7 ± 7.5 years) in China from 1998 to 2018. Nonlinear curves showed reverse J-shaped associations of BMI with cardiovascular disease (CVD), non-CVD and all-cause mortality, with a monotonic decreased risk up to BMIs in the overweight and mild obesity range and flat hazard ratios thereafter. Compared to normal weight, overweight and obesity were significantly associated with decreased non-CVD and all-cause mortality, but not with CVD mortality. Similar associations were found for waist circumference. Our results lend support to the notion that optimal BMI in the oldest old may be around the overweight or mild obesity range and challenge the application of international and national guidelines on optimal BMI in this age group.

Prediction of Cardiovascular and All-Cause Mortality After Myocardial Infarction in US Veterans

Risk prediction models for cardiovascular disease (CVD) death developed from patients without vascular disease may not be suitable for myocardial infarction (MI) survivors. Prediction of mortality risk after MI may help to guide secondary prevention. Using national electronic record data from the Veterans Health Administration 2002 to 2012, we developed risk prediction models for CVD death and all-cause death based on 5-year follow-up data of 100,601 survivors of MI using Cox proportional hazards models. Model performance was evaluated using a cross-validation approach. During follow-up, there were 31,622 deaths and 12,901 CVD deaths. In men, older age, current smoking, atrial fibrillation, heart failure, peripheral artery disease, and lower body mass index were associated with greater risk of death from CVD or all-causes, and statin treatment, hypertension medication, estimated glomerular filtration rate level, and high body mass index were significantly associated with reduced risk of fatal outcomes. Similar associations and slightly different predictors were observed in women. The estimated Harrell's C-statistics of the final model versus the cross-validation estimates were 0.77 versus 0.77 in men and 0.81 versus 0.77 in women for CVD death. Similarly, the C-statistics were 0.75 versus 0.75 in men, 0.78 versus 0.75 in women for all-cause mortality. The predicted risk of death was well calibrated compared with the observed risk. In conclusion, we developed and internally validated risk prediction models of 5-year risk for CVD and all-cause death for outpatient survivors of MI. Traditional risk factors, co-morbidities, and lack of blood pressure or lipid treatment were all associated with greater risk of CVD and all-cause mortality.

Protective effects of Aster yomena (Kitam.) Honda from cognitive dysfunction induced by high-fat diet

In our study, we investigated whether Aster yomena (Kitam.) Honda (AY) improved cognitive impairment which results from consumption of high-fat diet (HFD). When ethyl acetate fraction from AY (EFAY) was administered to C57BL/6J mice fed with 60% HFD, EFAY significantly enhanced cognitive ability that was impaired by HFD in T-maze test and novel object recognition test. Furthermore, EFAY increased memory and learning functions that were proven during Morris water maze test. We further elucidated protective mechanisms of EFAY against cognitive decline that resulted from obesity by western blotting. In the brain, HFD increased neuronal inflammation and disturbed insulin receptor substrate-1 (IRS-1)/Akt pathway. However, EFAY significantly downregulated inflammation-related protein expressions such as nuclear factor-κB interleukin-1β, inducible nitric oxide synthase and cyclooxygenase-2, compared with the HFD-fed control group. Furthermore, the IRS-1/Akt pathway was regulated by EFAY, indicating that EFAY ameliorated insulin resistance in the brain. PRACTICAL APPLICATIONS: Obesity and its complications increase the risk for developing cognitive dysfunction such as dementia. Administration of ethyl acetate fraction from AY (EFAY)-attenuated cognitive and memory impairment by inhibitions of neuronal oxidative stress and low-grade chronic inflammation in high-fat diet (HFD)-induced cognitive impairment mouse model. In addition, EFAY-administered mice disturbed cerebral insulin receptor substrate-1 (IRS-1)/Akt pathway. These data suggest that EFAY-improved cognitive impairment induced by HFD through modulation of insulin resistance and inflammation. Therefore, we proposed that AY could be a potential agent to prevent cognitive dysfunction induced by obesity and insulin resistance.

Gut microbiota in patients with obesity and metabolic disorders - a systematic review

BACKGROUND

Previous observational studies have demonstrated inconsistent and inconclusive results of changes in the intestinal microbiota in patients with obesity and metabolic disorders. We performed a systematic review to explore evidence for this association across different geography and populations.

METHODS

We performed a systematic search of MEDLINE (OvidSP) and Embase (OvidSP) of articles published from Sept 1, 2010, to July 10, 2021, for case-control studies comparing intestinal microbiome of individuals with obesity and metabolic disorders with the microbiome of non-obese, metabolically healthy individuals (controls). The primary outcome was bacterial taxonomic changes in patients with obesity and metabolic disorders as compared to controls. Taxa were defined as "lean-associated" if they were depleted in patients with obesity and metabolic disorders or negatively associated with abnormal metabolic parameters. Taxa were defined as "obesity-associated" if they were enriched in patients with obesity and metabolic disorders or positively associated with abnormal metabolic parameters.

RESULTS

Among 2390 reports screened, we identified 110 full-text articles and 60 studies were included. Proteobacteria was the most consistently reported obesity-associated phylum. Thirteen, nine, and ten studies, respectively, reported Faecalibacterium, Akkermansia, and Alistipes as lean-associated genera. Prevotella and Ruminococcus were obesity-associated genera in studies from the West but lean-associated in the East. Roseburia and Bifidobacterium were lean-associated genera only in the East, whereas Lactobacillus was an obesity-associated genus in the West.

CONCLUSIONS

We identified specific bacteria associated with obesity and metabolic disorders in western and eastern populations. Mechanistic studies are required to determine whether these microbes are a cause or product of obesity and metabolic disorders.

Moderate physical activity may not decrease the risk of cardiovascular disease in persistently overweight and obesity adults

Background

Body mass index (BMI) and physical activity (PA) has been documented to be associated with cardiovascular disease (CVD). However, the evidences regarding joint phenotypes of BMI and PA trajectories with risk for CVD and all-cause mortality are still limited.

Methods

Participants from the Kailuan Study, followed up during 2006–2019 were included, with primary outcomes of CVDs (myocardial infarction or stroke) and all-cause mortality. BMI and PA were repeatedly measured at least three times, and thus joint phenotypes trajectory groups were identified by group-based trajectory modeling. Cox proportional hazards models were used to examine the associations between trajectory groups and CVDs and all-cause mortality.

Results

Totally 88,141 (6 trajectories) and 89,736 participants (5 trajectories) were included in the final analyses relating trajectories to CVDs and all-cause mortality, respectively. Compared with persistent normal-weight with moderate PA group, participants were associated with increased risk of CVD in persistent overweight with moderate PA trajectory group (adjusted hazard ratio [aHR]: 1.31, 95% confidence interval [CI]: 1.22–1.41) and persistent obesity with moderate PA trajectory group (aHR: 1.55, 95% CI: 1.41–1.69). While the rising to overweight with moderate PA in normal-weight status with active PA (aHR: 0.72, 95% CI: 0.65–0.79), persistent overweight with moderate PA (aHR: 0.92, 95% CI: 0.87–0.97) and decline to normal-weight in overweight status with moderate PA (aHR: 0.73, 95% CI: 0.67–0.80) trajectories group were significantly associated with decreased all-cause mortality risk. The associations remained robust among stratifying by age and sex individuals and sensitive analysis.

Conclusions

The long-term trajectories analysis showed that moderate PA may not decrease the risk of CVD in persistently overweight and obesity adults.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03212-7.

The protective effects of Aster yomena (Kitam.) Honda on high-fat diet-induced obese C57BL/6J mice

BACKGROUND/OBJECTIVES

Aster yomena (Kitam.) Honda (AY) has remarkable bioactivities, such as antioxidant, anti-inflammation, and anti-cancer activities. On the other hand, the effects of AY against obesity-induced insulin resistance have not been reported. Therefore, this study examined the potential of AY against obesity-associated insulin resistance in high-fat diet (HFD)-fed mice.

MATERIALS/METHODS

An obesity model was established by feeding C57BL/6J mice a 60% HFD for 16 weeks. The C57BL6/When ethyl acetate fraction from AY (EFAY) at doses of 100 and 200 mg/kg/day was administered orally to mice fed a HFD for the last 4 weeks. Normal and control groups were administered water orally. The body weight and fasting blood glucose were measured every week. Dietary intake was measured every other day. After dissection, blood and tissues were collected from the mice.

RESULTS

The administration of EFAY reduced body and organ weights significantly compared to HFD-fed control mice. The EFAY-administered groups also improved the serum lipid profile by decreasing the triglyceride, total cholesterol, and low-density lipoprotein compared to the control group. In addition, EFAY ameliorated the insulin resistance-related metabolic dysfunctions, including the fasting blood glucose and serum insulin level, compared to the HFD-fed control mice. The EFAY inhibited lipid synthesis and insulin resistance by down-regulation of hepatic fatty acid synthase and up-regulation of the AMP-activated protein kinase pathway. EFAY also reduced lipid peroxidation in the liver, indicating that EFAY protected hepatic injury induced by obesity.

CONCLUSIONS

These results suggest that EFAY improved obesity-associated insulin resistance by regulating the lipid and glucose metabolism, suggesting that AY could be used as a functional food to prevent obesity and insulin resistance.

Adiposity and risks of vascular and non-vascular mortality among Chinese adults with type 2 diabetes: a 10-year prospective study

INTRODUCTION

Among individuals with diabetes, high adiposity has been associated with lower cardiovascular disease (CVD) mortality (the so-called 'obesity paradox' phenomenon) in Western populations, for reasons that are still not fully elucidated. Moreover, little is known about such phenomena in Chinese adults with diabetes among whom very few were obese. We aimed to assess the associations of adiposity with vascular and non-vascular mortality among individuals with diabetes, and compare these with associations among individuals without diabetes.

RESEARCH DESIGN AND METHODS

In 2004-2008, the prospective China Kadoorie Biobank recruited >512 000 adults from 10 areas in China. After ~10 years of follow-up, 3509 deaths (1431 from CVD) were recorded among 23 842 individuals with diabetes but without prior major diseases at baseline. Cox regression yielded adjusted HRs associating adiposity with mortality.

RESULTS

Among people with diabetes, body mass index (BMI) (mean 25.0 kg/m²) was positively log linearly associated with CVD incidence (n=9943; HR=1.19 (95% CI 1.15 to 1.22) per 5 kg/m²), but showed U-shaped associations with CVD and overall mortality, with lowest risk at 22.5-24.9 kg/m². At lower BMI, risk of death (n=671) within 28 days of CVD onset was particularly elevated, with an HR of 3.26 (95% CI 2.29 to 4.65) at <18.5 kg/m² relative to 22.5-24.9 kg/m², but no higher mortality risk at BMI ≥25.0 kg/m². These associations were similar in self-reported and screen-detected diabetes, and persisted after extensive attempts to address reverse causality and confounding. Among individuals without diabetes (mean BMI 23.6 kg/m²; n=23 305 deaths), there were less extreme excess mortality risks at low BMI.

CONCLUSIONS

Among relatively lean Chinese adults with diabetes, there were contrasting associations of adiposity with CVD incidence and with mortality. The high mortality risk at low and high BMI levels highlights, if causal, the importance of maintaining normal weight among people with diabetes.

Survival Analysis of Training Methodologies and Other Risk Factors for Musculoskeletal Injury in 2-Year-Old Thoroughbred Racehorses in Queensland, Australia

Musculoskeletal injuries remain a global problem for the Thoroughbred racing industry and there is conflicting evidence regarding the effect of age on the incidence of injuries. The ideal time to commence race training is strongly debated, with limited supporting literature. There is also conflicting evidence regarding the effect of high-speed exercise on musculoskeletal injuries. There is a strong interest in developing training and management strategies to reduce the frequency of injuries. The types of musculoskeletal injuries vary between 2-year-old and older horses, with dorsal metacarpal disease the most common injury in 2-year-old horses. It is likely that risk factors for injury in 2-year-old horses are different than those for older horses. It is also likely that the risk factors may vary between types of injury. This study aimed to determine the risk factors for musculoskeletal injuries and dorsal metacarpal disease. We report the findings of a large scale, prospective observational study of 2-year-old horses in Queensland, Australia. Data were collected weekly for 56-weeks, from 26 trainers, involving 535 2-year-old Thoroughbred racehorses, 1, 258 training preparations and 7, 512-weeks of exercise data. A causal approach was used to develop our statistical models, to build on the existing literature surrounding injury risk, by incorporating the previously established causal links into our analyses. Where previous data were not available, industry experts were consulted. Survival analyses were performed using Cox proportional hazards or Weibull regression models. Analysis of musculoskeletal injuries overall revealed the hazard was reduced with increased exposure to high-speed exercise [Hazard ratio (HR) 0.89, 95% Confidence Interval (CI) 0.84, 0.94, p < 0.001], increased number of training preparations (HR 0.58, 95% CI 0.50, 0.67, p < 0.001), increased rest before the training preparation (HR 0.89, 95% CI 0.83, 0.96, p = 0.003) and increased dam parity (HR 0.86, 95% CI 0.77, 0.97, p = 0.01). The hazard of injury was increased with increasing age that training commenced (HR 1.13, 95% CI 1.06, 1.19, p < 0.001). Analyses were then repeated with the outcome of interest dorsal metacarpal disease. Factors that were protective against dorsal metacarpal disease and musculoskeletal injuries overall included: increased total cumulative distance (HR 0.89, 95% CI 0.82, 0.97, p = 0.001) and total cumulative days exercised as a gallop (HR 0.96, 95% CI 0.92, 0.99, p = 0.03), the number of the training preparations (HR 0.43, 95% CI 0.30, 0.61, p < 0.001). The age that training commenced was harmful for both dorsal metacarpal disease (HR 1.17, 95% CI 1.07, 1.28, p < 0.001 and overall musculoskeletal injuries.). The use of non-ridden training modalities was protective for dorsal metacarpal disease (HR 0.89, 95% CI 0.81, 0.97, p = 0.008), but not musculoskeletal injuries overall. The male sex increased the hazard of DMD compared to females (HR 2.58, 95% CI 1.20, 5.56, p = 0.02), but not MSI overall. In summary, the hazard of musculoskeletal injury is greatest for 2-year-old horses that are born from uniparous mares, commence training at a later age, are in their first training preparation, have undertaken little high-speed exercise or had limited rest before their training preparation. The hazard of dorsal metacarpal disease is greatest for 2-year-old horses that are males, commence training at a later age, are in their first training preparation, have undertaken little high-speed exercise or had limited use of non-ridden training modalities. Close monitoring of these high-risk horses during their training program could substantially reduce the impact of MSI. Furthermore, an understanding of how training methodologies affect the hazard of MSI facilitates modification of training programs to mitigate the risk impact of injury. The strengths of this study include a large sample size, a well-defined study protocol and direct trainer interviews. The main limitation is the inherent susceptibility to survival bias.

Postdiagnosis BMI Change Is Associated with Non-Small Cell Lung Cancer Survival

BACKGROUND

Body mass index (BMI) change after a lung cancer diagnosis has been associated with non-small cell lung cancer (NSCLC) survival. This study aimed to quantify the association based on a large-scale observational study.

METHODS

Included in the study were 7,547 patients with NSCLC with prospectively collected BMI data from Massachusetts General Hospital and Brigham and Women's Hospital/Dana-Farber Cancer Institute. Cox proportional hazards regression with time-dependent covariates was used to estimate effect of time-varying postdiagnosis BMI change rate (% per month) on overall survival (OS), stratified by clinical subgroups. Spline analysis was conducted to quantify the nonlinear association. A Mendelian Randomization (MR) analysis with a total of 3,495 patients further validated the association.

RESULTS

There was a J-shape association between postdiagnosis BMI change and OS among patients with NSCLC. Specifically, a moderate BMI decrease [0.5-2.0; HR = 2.45; 95% confidence interval (CI), 2.25-2.67] and large BMI decrease (≥2.0; HR = 4.65; 95% CI, 4.15-5.20) were strongly associated with worse OS, whereas moderate weight gain (0.5-2.0) reduced the risk for mortality (HR = 0.78; 95% CI, 0.68-0.89) and large weight gain (≥2.0) slightly increased the risk of mortality without reaching statistical significance (HR = 1.10; 95% CI, 0.86-1.42). MR analyses supported the potential causal roles of postdiagnosis BMI change in survival.

CONCLUSIONS

This study indicates that BMI change after diagnosis was associated with mortality risk.

IMPACT

Our findings, which reinforce the importance of postdiagnosis BMI surveillance, suggest that weight loss or large weight gain may be unwarranted.

A comorbid mental disorder paradox: Using causal diagrams to understand associations between posttraumatic stress disorder and suicide

OBJECTIVE

Although some studies document that posttraumatic stress disorder (PTSD) increases suicide risk, other studies have produced the paradoxical finding that PTSD decreases suicide risk. We sought to understand methodologic biases that may explain these paradoxical findings through the use of directed acyclic graphs (DAGs).

METHOD

DAGs are causal diagrams that visually encode a researcher's assumptions about data generating mechanisms and assumed causal relations among variables. DAGs can connect theories to data and guide statistical choices made in study design and analysis. In this article, we describe DAGs and explain how they can be used to identify biases that may arise from inappropriate analytic decisions and data limitations.

RESULTS

We define a particular form of bias, collider bias, that is a likely explanation for why studies have found a supposedly protective association of PTSD with suicide. This protective association is interpreted by some researchers as evidence that PTSD reduces the risk of suicide. Collider bias may occur through inappropriate adjustment for a psychiatric comorbidity, such as adjustment for variables that are affected by PTSD and share common causes with suicide.

CONCLUSIONS

We recommend that researchers collect longitudinal measurements of psychiatric comorbidities, which would help establish the temporal ordering of variables and avoid the biases discussed in this article. Furthermore, researchers could use DAGs to explore how results may be impacted by design and analytic decisions prior to execution. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Impact of Low Body Mass Index on Features of Coronary Culprit Plaques and Outcomes in Patients With Acute Coronary Syndrome

The mechanisms behind poorer cardiac outcomes in underweight patients with acute coronary syndrome (ACS) are not understood and features of coronary culprit lesions in underweight ACS patients have not been fully examined. A total of 1,683 patients with ACS were divided into 4 groups according to body mass index (BMI): <18.5 (n = 73), 18.5 to 24.9 (n = 995), 25 to 29.9 (n = 488), and ≥30 (n = 117). Angiography and optical coherence tomography (OCT) images were analyzed for 1,428 of these patients who had primary percutaneous coronary intervention (PCI) and 838 who had primary PCI with OCT guidance, respectively. Diabetes (p <0.001), hypertension (p <0.001), and dyslipidemia (p <0.001) were less prevalent in BMI <18.5. Statin prescription at discharge was less frequent in the BMI <18.5 group (p <0.001). Quantitative coronary angiography analyses revealed smaller reference vessel (p = 0.001) and minimum lumen diameters after PCI (p = 0.019) and OCT revealed longer lipidic plaque length (p = 0.029) in the BMI <18.5 group. Kaplan-Meier analyses revealed higher rates of cardiac mortality (p <0.001) and major bleeding (p = 0.034) during the 2-year follow-up in the BMI <18.5 group. After adjusting for traditional cardiovascular risk factors, BMI <18.5 independently predicted 2-year cardiac mortality (hazard ratio 1.917 [95% confidence interval [1.082 to 3.397], p = 0.026). In conclusion, being underweight contributed to poorer cardiac outcomes in established ACS population. Smaller minimum lumen diameter after PCI and further progressed atherosclerosis at the culprit lesions despite their lower prevalence of comorbid metabolic risk factors may be related partly to poorer cardiac outcomes.

Obesity measures, metabolic health and their association with 15-year all-cause and cardiovascular mortality in the SAMINOR 1 Survey: a population-based cohort study

Background

The mortality of metabolic-obesity phenotypes has been thoroughly studied, but it is not known if or how the association between mortality and body mass index (BMI), waist circumference or a body shape index (ABSI) differ in strata of cardiometabolic health status.

Methods

We linked data on 12,815 men and women aged 36–79 years from the SAMINOR 1 Survey with mortality data from the Norwegian Cause of Death Registry. We defined metabolically healthy and unhealthy as having zero and ≥ 1, respectively, of the following: MetS, pre-existing diabetes or cardiovascular disease (CVD), or prescribed drugs for high blood pressure, hyperglycaemia or dyslipidaemia. We defined general and abdominal obesity as BMI ≥ 30 kg/m² and waist circumference ≥ 88 cm (women) or 102 cm (men), respectively, and cross-classified these categories with metabolic status to create metabolically healthy non-obese and obese (MHNO and MHO) and metabolically unhealthy non-obese and obese (MUNO and MUO) phenotypes. We used Cox regression to estimate the hazard ratio (HR) for all-cause and CVD mortality for 1) the four phenotypes and 2) BMI, waist circumference and ABSI fitted with restricted cubic splines. We adjusted for age and lifestyle, and tested for interactions with sex and metabolic status (only continuous measures).

Results

The MHO phenotype was present in 7.8% of women and 5.8% of men. During a median follow-up of 15.3/15.2 years, 596/938 women/men had died, respectively. The MUNO and MUO groups had higher mortality than the MHNO group. Sex and phenotypes interacted with respect to CVD mortality: relative to the MHNO group, the MHO group had an adjusted HR (95% confidence interval) for CVD mortality of 1.05 (0.38–2.88) in women and 2.92 (1.71–5.01) in men. We found curvilinear associations between BMI/waist circumference and all-cause mortality irrespective of metabolic status. Corresponding relationships with CVD mortality were linear and the slope differed by sex and metabolic status. ABSI was linearly and positively associated with all-cause and CVD mortality in men.

Conclusion

The relationships between BMI, waist circumference or ABSI and mortality differed by sex, metabolic status and cause of death. Poor metabolic health substantially increases mortality regardless of obesity status.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02288-9.

Association of Body Mass Index with Survival in Asian Patients with Colorectal Cancer

Purpose

The clinical significance of body mass index (BMI) on long-term outcomes has not been extensively investigated in Asian patients with colorectal cancer (CRC). This study aims to describe the association between BMI and survival, plus providing BMI cutoff value for predicting prognosis in CRC patients.

Materials and Methods

A total of 1,182 patients who had undergone surgery for stage I–III CRC from June 2004 to February 2014 were included. BMI was categorized into four groups based on the recommendation for Asian ethnicity. The optimal BMI cutoff value was determined to maximize overall survival (OS) difference.

Results

In multivariable analysis, underweight BMI was significantly associated with poor OS (hazard ratio [HR], 2.38; 95% confidence interval [CI], 1.55 to 3.71; p < 0.001) and obese BMI was associated with better OS (HR, 0.72; 95% CI, 0.53 to 0.97; p=0.036) compared with the normal BMI. Overweight and obese BMI were associated with better recurrence-free survival (HR, 0.64; 95% CI, 0.42 to 0.99; p=0.046 and HR, 0.58; 95% CI, 0.38 to 0.89; p=0.014, respectively) compared with the normal BMI group. BMI cutoff value was 20.44 kg/m². Adding the BMI cutoff value to cancer staging could increase discriminatory performance in terms of integrated area under the curve and Harrell’s concordance index.

Conclusion

Compared to normal BMI, underweight BMI was associated with poor survival whereas obese BMI was associated with better survival. BMI cutoff value of 20.44 kg/m² is a useful discriminator in Asian patients with CRC.

Challenging the obesity paradox: extreme obesity and COPD mortality in the SUMMIT trial

Populations with COPD demonstrate higher survival in overweight and obese compared with normal weight; the “obesity paradox”. Relationships in less-severe COPD are unclear, as is the impact of cardiovascular risk, and few studies include individuals at extremes of obesity.

 We examined the relationship between body mass index (BMI; defined as underweight: <20 kg·m⁻², normal: 20–25 kg·m⁻², overweight: 25– <30 kg·m⁻², obese class I: 30– <35 kg·m⁻², class II: 35– <40 kg·m⁻² and class III: ≥40 kg·m⁻²), morbidity, and mortality in the SUMMIT trial population (n=16 485), characterised by moderate COPD and heightened cardiovascular risk with a substantial proportion with class III obesity. The association between BMI category and time to event was modelled via proportional hazards (reference normal weight) adjusted for demographics and cardiorespiratory disease.

 Consistent with the paradox, underweight individuals demonstrated higher mortality (hazard ratio (HR) 1.31 (95% CI 1.04–1.64)), with lower mortality among overweight (HR 0.62 (95% CI 0.52–0.73)) and obese class I (HR 0.75 (95% CI 0.62–0.90)). However, mortality increased in obese class III (HR 1.36 (95% CI 1.00–1.86)). Death was primarily attributable to cardiovascular causes.

 Within a large, multinational cohort with moderate COPD and increased cardiovascular risk, the phenomenon of reduced mortality with obesity did not persist at BMI >40 kg·m⁻², suggesting that obesity may not remain protective at the extremes in this population.

In a population with moderate COPD, at heightened cardiovascular risk and containing a substantial proportion of individuals with BMI ≥40 kg/m², BMI and mortality demonstrate a U-shaped (rather than J-shaped) relationshiphttps://bit.ly/3hDztI6

The obesity paradox in metastatic castration-resistant prostate cancer

OBJECTIVE

To test whether body mass index (BMI) amongst patients with metastatic castration-resistant prostate cancer (mCRPC) is associated with overall survival (OS) and cancer-specific survival.

METHODS

Individual patient data from 1577 men with mCRPC treated with docetaxel and prednisone from the control arms of ASCENT2, VENICE, and MAINSAIL were considered. The role of BMI on survival outcomes was investigated both as a continuous and categorical variable (≤24.9 vs. 25-29.9 vs. ≥30 km/m²). BMI ≥ 30 kg/m² was considered obese. Analyses were adjusted for age, PSA, ECOG performance status, number of metastases and prior treatment. The Cox semi-proportional hazard model was used to predict OS, whereas competing risks regression was used for predicting cancer-specific mortality (CSM). To exclude any possible effect attributable to higher doses of chemotherapy (titrated according to body-surface area), we checked for eventual interactions between BMI and chemotherapy dose (both as continuous-continuous and categorical-continuous interactions).

RESULTS

The median (IQR) age for the patient population was 69 (63,74) years with a median (IQR) BMI of 28 (25-31) kg/m². Median follow-up for survivors was 12 months. Of the 1577 patients included, 655 were deceased by the end of the studies. Regarding OS, BMI emerged as a protective factor both as a continuous variable (HR: 0.96; 95% CI: 0.94, 0.99; p = 0.015) and as a categorical variable (obesity: HR: 0.71, 95% CI: 0.53, 0.96; p = 0.027, relatively to normal weight). The protective effect of high BMI on CSM was confirmed both as a continuous (SHR: 0.94; 95% CI: 0.91, 0.98; p = 0.002) and as a categorical variable (obesity SHR: 0.65; 95% CI: 0.45, 0.93; p = 0.018). No interaction was detected between the BMI categories and the docetaxel dose at any level in our analyses (all p » 0.05).

CONCLUSIONS

Obese patients with mCRPC had better cancer-specific and overall survival as compared to overweight and normal weight patients. The protective effect of BMI was not related to receiving higher chemotherapy doses. Further studies aimed at elucidating the biological mechanism behind this effect are warranted.

A Unification of Mediator, Confounder, and Collider Effects

Third-variable effects, such as mediation and confounding, are core concepts in prevention science, providing the theoretical basis for investigating how risk factors affect behavior and how interventions change behavior. Another third variable, the collider, is not commonly considered but is also important for prevention science. This paper describes the importance of the collider effect as well as the similarities and differences between these three third-variable effects. The single mediator model in which the third variable (T) is a mediator of the independent variable (X) to dependent variable (Y) effect is used to demonstrate how to estimate each third-variable effect. We provide difference in coefficients and product of coefficients estimators of the effects and demonstrate how to calculate these values with real data. Suppression effects are defined for each type of third-variable effect. Future directions and implications of these results are discussed.

Fitness vs. fatness as determinants of survival in non-institutionalized older adults: The EXERNET multi-center study

BACKGROUND

Physical fitness and body composition are important health indicators, nevertheless their combined pattern inter-relationships and their association with mortality are poorly investigated.

METHODS

This longitudinal study is part of the Spanish EXERNET-Elder project. Person-months follow-up were calculated from the interview date, performed between June 2008 and November 2009, until date of death or censoring on March 2018 (whichever came first). In order to be included, participants had to fulfill the following criteria: 1) be over 65 years old, 2) live independently at home, 3) not suffer dementia and/or cancer and 4) have a BMI above 18.5. Body fat and weight were assessed by a bioelectrical impedance analyzer. Fitness was measured with the Senior Fitness and the one leg static balance tests. The Spanish Death Index was consulted for the death's identification. Cluster analysis was performed to identify Fat-Fit patterns and traditional cut points and percentiles to create the Fat-Fit groups. Cox proportional hazards regression models were used to calculate the hazard ratios of death in clustered Fat-Fit patterns and in traditional Fat-Fit groups.

RESULTS

A total of 2299 older adults (76.8% of women) were included with a baseline mean age of 71.9 ± 5.2 years. A total of 196 deaths (8.7% of the sample) were identified during the 8 years of follow up. Four clustered Fat-Fit patterns (Low fat-Fit, Medium fat-Fit, High fat-Unfit and Low fat-Unfit) and nine traditional Fat-Fit groups emerged. Using the Low fat-Fit pattern as the reference, significantly increased mortality was noted in High fat-Unfit (HR: 1.68, CI: 1.06 - 2.66) and Low fat-Unfit (HR: 2.01, CI: 1.28 - 3.16) groups. All the traditional Fit groups showed lower mortality risk when compared to the reference group (obese-unfit group).

CONCLUSIONS

Physical fitness is a determinant factor in terms of survival in community-dwelling older adults, independently of adiposity levels.

The association between outcomes and body mass index in patients with acute respiratory distress syndrome

INTRODUCTION

Limited information exists about the relationship between body mass index (BMI) and the outcome of acute respiratory distress syndrome (ARDS).

OBJECTIVE

To evaluate the hospital mortality of patients with ARDS in relation to BMI.

MATERIALS AND METHODS

We conducted a retrospective, multicenter study including patients with ARDS. ARDS was defined according to the Berlin criteria. Body weight and height were obtained to calculate BMI. The primary outcome was in-hospital mortality. Secondary outcomes were intensive care unit (ICU) mortality, invasive positive pressure ventilation (IPPV) free days within 28 days and length of stays in the ICU and hospital.

RESULTS

Among 523 patients, 28 (5%) were underweight (BMI <18.5 kg/m² ), 299 (57%) were normal weight (BMI 18.5-24.9 kg/m² ), 159 (30%) were overweight (BMI 25-29.9 kg/m² ) and 37 (7%) were obese (BMI ≥30 kg/m² ). Increasing BMI was associated with younger age (P = 0.017), hypertension (P = 0.003) and diabetes (P = 0.02). Compared with normal weight, being overweight and obese resulted in lower mortality regardless of whether in the hospital (P = 0.019) or ICU (P = 0.044). However, after risk adjustment, only obesity was associated with lower hospital mortality (OR 0.393, 95% CI 0.169-0.914, P = 0.030). With the increase of BMI, the in-hospital mortality and ICU mortality of ARDS dropped gradually (from 57.1% to 24.3%, P = 0.021, and from 53.6% to 24.3%, P = 0.035).

CONCLUSIONS

Obesity is associated with lower mortality in patients with ARDS. With the increase of BMI, the mortality of ARDS drops gradually.

Obesity and All Cause Mortality Following Acute Coronary Syndrome (ANZACS QI 53)

BACKGROUND

Some studies have suggested a lower mortality in obese subjects with cardiovascular disease. The aim of this study was to evaluate the relationship between body mass index (BMI) and outcomes in patients with acute coronary syndrome (ACS).

METHODS

The study included 13,742 patients undergoing coronary angiography for ACS between 2012 and 2016 from the All New Zealand Acute Coronary Syndrome-Quality Improvement (ANZACS-QI) registry. Patients were categorised by BMI (kg/m²) as: underweight <18.5, normal 18.5 to <25, overweight 25 to <30, mildly obese 30 to <35, moderately obese 35 to <40, and severely obese ≥40. The primary endpoint of the study was all cause mortality with secondary endpoints of cardiovascular disease (CVD) and non-CVD mortality within 4 years of discharge.

RESULTS

Unadjusted all cause mortality was lowest in the mildy obese but no different to normal or overweight after adjustment for multiple confounders. Adjusted all cause mortality was higher in the moderately (hazard ratio [HR] 1.39, 95% CI: 1.10-1.75) and severely obese (2.06, 95% CI: 1.57-2.70) compared to the mildly obese. Non-CVD mortality (HR 1.58, 95% CI: 1.12-2.23) was the major contributor to higher all cause mortality in moderately obese patients. Both CVD mortality (HR 2.36, 95% CI: 1.67-3.32) and non-CVD mortality (HR 1.67, 95% CI: 1.07-2.61) contributed to higher all cause mortality in the severely obese.

CONCLUSIONS

Moderate and severe obesity is associated with worse survival post ACS influenced by higher non-CVD mortality in moderate/severe obesity and higher CVD mortality in severe obesity.

Visceral obesity is associated with lower stage colon tumors in males without survival advantage

Visceral obesity and systemic inflammatory response (SIR) were suggested to be closely related to colon cancer (CC) oncological and surgical outcomes. The first by producing several soluble factors involved in carcinogenesis and the second for having a key role in the nutritional and functional decline of patients with cancer. Furthermore, gender differences in relative body composition and adipose tissue regional distribution have also been acknowledged to influence CC. The primary aim of this study was to determine whether visceral adiposity, stratified by gender, influenced CC staging and prognosis. As secondary aim, this study evaluated whether visceral adiposity and SIR markers were associated with CC pathological features so that these could be used in clinical practice to predict disease outcomes and potentially influence therapeutic decisions. Case records from patients (n = 300) submitted to CC surgical resection at a single tertiary hospital were retrospectively reviewed to retrieve clinical, laboratory, imaging and pathological data. Visceral fat area was quantified by computerized morphometric analysis in preoperative tomography scans. Visceral obesity was defined as visceral fat area ≥160 cm² for men and ≥80 cm² for women. Preoperative full blood count performed as part of the routine clinical assessment at the hospital laboratory was used to obtain C-reactive protein (CRP) levels and to calculate neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), which were used as SIR markers. One hundred and forty-three (n = 143) patients fulfilled eligibility criteria and were included in the analysis. Patients with high-visceral adipose tissue (vAT) had smaller size CC tumors (p < 0.001), earlier T-stage disease (p = 0.027) and lower nodal involvement (p = 0.039). In gender subgroup analysis, these findings were only confirmed in males. Moreover, male patients with high-vAT also had a lower proportion of metastatic nodes (p = 0.021) and metastatic to dissected lymph node ratio (p = 0.030). Additionally, patients with high-vAT also had lower PLR (p = 0.001). CC survival was not influenced by visceral obesity, gender nor SIR. In conclusion, our study shows that male patients with high visceral adiposity have lower PLR levels and earlier stage tumors. Furthermore, our data suggests that visceral obesity and SIR despite being associated with earlier stage CC tumors do not seem to present a survival advantage.

A systematic review of quantitative bias analysis applied to epidemiological research

BACKGROUND

Quantitative bias analysis (QBA) measures study errors in terms of direction, magnitude and uncertainty. This systematic review aimed to describe how QBA has been applied in epidemiological research in 2006-19.

METHODS

We searched PubMed for English peer-reviewed studies applying QBA to real-data applications. We also included studies citing selected sources or which were identified in a previous QBA review in pharmacoepidemiology. For each study, we extracted the rationale, methodology, bias-adjusted results and interpretation and assessed factors associated with reproducibility.

RESULTS

Of the 238 studies, the majority were embedded within papers whose main inferences were drawn from conventional approaches as secondary (sensitivity) analyses to quantity-specific biases (52%) or to assess the extent of bias required to shift the point estimate to the null (25%); 10% were standalone papers. The most common approach was probabilistic (57%). Misclassification was modelled in 57%, uncontrolled confounder(s) in 40% and selection bias in 17%. Most did not consider multiple biases or correlations between errors. When specified, bias parameters came from the literature (48%) more often than internal validation studies (29%). The majority (60%) of analyses resulted in >10% change from the conventional point estimate; however, most investigators (63%) did not alter their original interpretation. Degree of reproducibility related to inclusion of code, formulas, sensitivity analyses and supplementary materials, as well as the QBA rationale.

CONCLUSIONS

QBA applications were rare though increased over time. Future investigators should reference good practices and include details to promote transparency and to serve as a reference for other researchers.

BMI and risk of all-cause mortality in normotensive and hypertensive adults: the rural Chinese cohort study

OBJECTIVE

The impact of baseline hypertension status on the BMI-mortality association is still unclear. We aimed to examine the moderation effect of hypertension on the BMI-mortality association using a rural Chinese cohort.

DESIGN

In this cohort study, we investigated the incident of mortality according to different BMI categories by hypertension status.

SETTING

Longitudinal population-based cohort.

PARTICIPANTS

17 262 adults ≥18 years were recruited from July to August of 2013 and July to August of 2014 from a rural area in China.

RESULTS

During a median 6-year follow-up, we recorded 1109 deaths (610 with and 499 without hypertension). In adjusted models, as compared with BMI 22-24 kg/m2, with BMI ≤ 18, 18-20, 20-22, 24-26, 26-28, 28-30 and >30 kg/m2, the hazard ratios for mortality in normotensive participants were 1·92 (95% CI 1·23, 3·00), 1·44 (95% CI 1·01, 2·05), 1·14 (95% CI 0·82, 1·58), 0·96 (95% CI 0·70, 1·31), 0·96 (95% CI 0·65, 1·43), 1·32 (95% CI 0·81, 2·14) and 1·32 (95% CI 0·74, 2·35), respectively, and in hypertensive participants were 1·85 (95% CI 1·08, 3·17), 1·67 (95% CI 1·17, 2·39), 1·29 (95% CI 0·95, 1·75), 1·20 (95% CI 0·91, 1·58), 1·10 (95% CI 0·83, 1·46), 1·10 (95% CI 0·80, 1·52) and 0·61 (95% CI 0·40, 0·94), respectively. The risk of mortality was lower in individuals with hypertension with overweight or obesity v. normal weight, especially in older hypertensives (≥60 years old). Sensitivity analyses gave consistent results for both normotensive and hypertensive participants.

CONCLUSIONS

Low BMI was significantly associated with increased risk of all-cause mortality regardless of hypertension status in rural Chinese adults, but high BMI decreased the mortality risk among individuals with hypertension, especially in older hypertensives.

Effect of Body Mass Index on the Prognosis of Liver Cirrhosis

Objective: At present, the association of body mass index (BMI) with the prognosis of liver cirrhosis is controversial. Our retrospective study aimed to evaluate the impact of BMI on the outcome of liver cirrhosis. Methods: In the first part, long-term death was evaluated in 436 patients with cirrhosis and without malignancy from our prospectively established single-center database. In the second part, in-hospital death was evaluated in 379 patients with cirrhosis and with acute gastrointestinal bleeding (AGIB) from our retrospective multicenter study. BMI was calculated and categorized as underweight (BMI <18.5 kg/m²), normal weight (18.5 ≤ BMI < 23.0 kg/m²), and overweight/obese (BMI ≥ 23.0 kg/m²). Results: In the first part, Kaplan-Meier curve analyses demonstrated a significantly higher cumulative survival rate in the overweight/obese group than the normal weight group (p = 0.047). Cox regression analyses demonstrated that overweight/obesity was significantly associated with decreased long-term mortality compared with the normal weight group [hazard ratio (HR) = 0.635; 95% CI: 0.405-0.998; p = 0.049] but not an independent predictor after adjusting for age, gender, and Child-Pugh score (HR = 0.758; 95%CI: 0.479-1.199; p = 0.236). In the second part, Kaplan-Meier curve analyses demonstrated no significant difference in the cumulative survival rate between the overweight/obese and the normal weight groups (p = 0.094). Cox regression analyses also demonstrated that overweight/obesity was not significantly associated with in-hospital mortality compared with normal weight group (HR = 0.349; 95%CI: 0.096-1.269; p = 0.110). In both of the two parts, the Kaplan-Meier curve analyses demonstrated no significant difference in the cumulative survival rate between underweight and normal weight groups. Conclusion: Overweight/obesity is modestly associated with long-term survival in patients with cirrhosis but not an independent prognostic predictor. There is little effect of overweight/obesity on the short-term survival of patients with cirrhosis and with AGIB.

Association between obesity and hospital mortality in critical COVID-19: a retrospective cohort study

BACKGROUND

The impact of obesity on outcomes in acute respiratory distress syndrome (ARDS) is not well understood and remains controversial. Recent studies suggest that obesity might be associated with higher morbidity and mortality in respiratory disease caused by SARS-CoV-2 (COVID-19 disease). Our objective was to evaluate the association between obesity and hospital mortality in critical COVID-19 patients.

METHODS

We conducted a retrospective cohort study in a tertiary academic center located in Montréal between March and August 2020. We included all consecutive adult patients admitted to the ICU for COVID-19-confirmed respiratory disease. Our main outcome was hospital mortality. We estimated the association between obesity, using the body mass index as a continuous variable, and hospital survival by fitting a multivariable Cox proportional hazards model.

RESULTS

We included 94 patients. Median [q1, q3] body mass index (BMI) was 29 [26-32] kg/m² and 37% of patients were obese (defined as BMI > 30 kg/m²). Hospital mortality for the entire cohort was 33%. BMI was significantly associated with hospital mortality (hazard ratio [HR] = 2.49 per 10 units BMI; 95% CI, from 1.69 to 3.70; p < 0.001) even after adjustment for sex, age and obesity-related comorbidities (adjusted HR = 3.50; 95% CI from 2.03 to 6.02; p < 0.001).

CONCLUSIONS

Obesity was prevalent in hospitalized patients with critical illness secondary to COVID-19 disease and a higher BMI was associated with higher hospital mortality. Further studies are needed to validate this association and to better understand its underlying mechanisms.

Relation of Body Mass Index to Outcomes in Acute Coronary Syndrome

We assessed the association of BMI with all-cause and cardiovascular (CV) mortality in a contemporary acute coronary syndrome cohort. Patients from the Australian Cooperative National Registry of Acute Coronary Care, Guideline Adherence and Clinical Events and Global Registry of Acute Coronary Events between 2009 and 2019, were divided into BMI subgroups (underweight: <18.5, healthy: 18.5 to 24.9, overweight: 25 to 29.9, obese: 30 to 39.9, extremely obese: >40). Logistic regression was used to determine the association between BMI group and outcomes of all cause and CV death in hospital, and at 6 months. 8,503 patients were identified, mean age 64 ± 13, 72% male. The BMI breakdown was: underweight- 95, healthy- 2,140, overweight- 3,258, obese- 2,653, extremely obese- 357. Obese patients were younger (66 ± 12 vs 67 ± 13), with more hypertension, diabetes, and dyslipidemia vs healthy (all p < 0.05). Obese had lower hospital mortality than healthy: all-cause: 1% versus 4%, aOR (95% CI): 0.49(0.27, 0.87); CV: 1% versus 3%, 0.51(0.27, 0.96). At 6-month underweight had higher mortality than healthy: all-cause: 11% versus 4%, 2.69(1.26, 5.76); CV: 7% versus 1%, 3.54(1.19, 10.54); whereas obese had lower mortality: all-cause: 1% versus 4%, 0.48(0.29, 0.77); CV: 0.4% versus 1%, 0.42(0.19, 0.93). When BMI was plotted as a continuous variable against outcome a U-shaped relationship was demonstrated, with highest event rates in the most obese (>60). In conclusion, BMI is associated with mortality following an acute coronary syndrome. Obese patients had the best outcomes, suggesting persistence of the obesity paradox. However, there was a threshold effect, and favorable outcomes did not extend to the most obese.