Challenging the obesity paradox: extreme obesity and COPD mortality in the SUMMIT trial.
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SUBMITTER: Brigham EP
PROVIDER: S-EPMC8311131 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Background and purposeObesity is an established risk factor for ischemic stroke but the association of increased body mass index (BMI) with survival after ischemic stroke remains controversial. Many studies have shown that increased BMI has a "protective" effect on survival after stroke while other studies have debunked the "obesity paradox". This study aimed at examining the relationship between BMI and all-cause mortality at one year in first-time ischemic stroke patients using a large dataset extracted from different resources including electronic health records.MethodsThis was a retrospective cohort study of consecutive ischemic stroke patients captured in our Geisinger NeuroScience Ischemic Stroke (GNSIS) database. Survival in first-time ischemic stroke patients in different BMI categories was analyzed using Kaplan Meier survival curves. The predictors of mortality at one-year were assessed using a stratified Cox proportional hazards model.ResultsAmong 6,703 first-time ischemic stroke patients, overweight and obese patients were found to have statistically decreased hazard ratio (HR) compared to the non-overweight patients (overweight patients- HR = 0.61 [95% CI, 0.52-0.72]; obese patients- HR = 0.56 [95% CI, 0.48-0.67]). Predictors with a significant increase in the hazard ratio for one-year mortality were age at the ischemic stroke event, history of neoplasm, atrial fibrillation/flutter, diabetes, myocardial infarction and heart failure.ConclusionOur study results support the obesity paradox in ischemic stroke patients as shown by a significantly decreased hazard ratio for one-year mortality among overweight and obese patients in comparison to non-overweight patients.
| S-EPMC7875337 | biostudies-literature
Project description:ObjectiveTo determine the combined effects of body mass index (BMI) and body fat (BF) on prognosis in coronary heart disease (CHD) to better understand the obesity paradox.Patients and methodsWe studied 581 patients with CHD between January 1, 2000, and July 31, 2005, who were divided into low (<25) and high BMI (≥25), as well as low (≤25% men and ≤35% women) and high BF (>25% in men and >35% in women). Four groups were analyzed by total mortality during the 3-year follow-up by National Death Index: low BF/low BMI (n=119), high BF/low BMI (n=26), low BF/high BMI (n=125), and high BF/high BMI (n=311).ResultsDuring the 3-year follow-up, mortality was highest in the low BF/low BMI group (11%), which was significantly (P<.001) higher than that in the other 3 groups (3.9%, 3.2%, and 2.6%, respectively); using the high BF/high BMI group as a reference, the low BF/low BMI group had a 4.24-fold increase in mortality (confidence interval [CI], 1.76-10.23; P=.001). In multivariate logistic regression for mortality, when entered individually, both high BMI (odds ratio [OR], 0.79; CI, 0.69-0.90) and high BF (OR, 0.89; CI, 0.82-0.95) as continuous variables were independent predictors of better survival, whereas low BMI (OR, 3.60; CI, 1.37-9.47) and low BF (OR, 3.52; CI, 1.34-9.23) as categorical variables were independent predictors of higher mortality.ConclusionAlthough both low BF and low BMI are independent predictors of mortality in patients with CHD, only patients with combined low BF/low BMI appear to be at particularly high risk of mortality during follow-up. Studies are needed to determine optimal body composition in the secondary prevention of CHD.
| S-EPMC3257992 | biostudies-literature
Project description:ObjectivesThe purpose of this study was to determine whether there is a dose-response relationship between body mass index (BMI) and all-cause mortality in patients after coronary revascularization.MethodsThe MIMIC-III database (version 1.4) was used as the sample population. For variables with less than 10% of values missing, we used the mice package of R software for multiple imputations. Cox regression was used to determine the risk factors of all-cause mortality in patients. RCSs were used to observe the relationship between BMI and all-cause mortality. Additional subgroup and sensitivity analyses were also performed to explore whether the conclusion can be applied to specific groups.ResultsBoth univariate and multivariate Cox models indicated that the mortality risk was lower for overweight patients than for normal-weight patients (P < 0.05). In RCS models, BMI had a U-shaped relationship with all-cause mortality of patients after coronary artery bypass grafting (CABG) (P for nonlinearity = 0.0028). There was a weak U-shaped relationship between BMI and all-cause mortality after percutaneous coronary intervention (PCI), but the nonlinear relationship between these two parameters was not significant (P for nonlinearity = 0.1756).ConclusionsThe obesity paradox does exist in patients treated with CABG and PCI. RCS analysis indicated that there was a U-shaped relationship between BMI and all-cause mortality in patients after CABG. After sex stratification, the relationship between BMI and all-cause mortality in male patients who received PCI was L-shaped, while the nonlinear relationship among females was not significant.
| S-EPMC8616700 | biostudies-literature
Project description:AimsTo investigate the obesity paradox and association of extreme obesity with long-term outcomes among older ST-segment elevation myocardial infarction (STEMI) patients.Methods and resultsNineteen thousand four hundred and ninety-nine patients ≥65 years with STEMI surviving to hospital discharge in NCDR ACTION Registry-GWTG linked to Centers for Medicare and Medicaid Services outcomes between 2007 and 2012 were stratified by body mass index (BMI) (kg/m2) into normal weight (18.5-24.9), overweight (25-29.9), class I (30-34.9), class II (35-39.9), and class III/extreme obese (≥40) categories. Multivariable-adjusted associations were evaluated between BMI categories and mortality by Cox proportional hazards models, and days alive and out of hospital (DAOH) by generalized estimating equations, within 3 years after discharge. Seventy percent of patients were overweight/obese and 3% extremely obese. Normal weight patients were older and more likely to smoke; while extremely obese patients were younger and more likely to be female and black, with lower socioeconomic status and more comorbidity (P ≤ 0.001). A U-shaped association was observed between BMI categories and mortality: patients with class I obesity were at lowest risk, while normal weight [hazard ratio (HR) 1.30, 95% confidence interval (CI) 1.15-1.47] and extremely obese patients (HR 1.33, 95% CI 1.02-1.74) had higher mortality. Normal weight [odds ratio (OR) 0.79, 95% CI 0.68-0.90] and extremely obese (OR 0.73, 95% CI 0.54-0.99) individuals also had lower odds of DAOH.ConclusionMild obesity is associated with lower long-term risk in older STEMI patients, while normal weight and extreme obesity are associated with worse outcomes. These findings highlight hazards faced by an increasing number of older individuals with normal weight or extreme obesity and cardiovascular disease.
| S-EPMC5596997 | biostudies-literature
Project description:AimsTo characterize the relationship between blood pressure (BP) or heart rate and mortality and morbidity in chronic obstructive pulmonary disease (COPD).Methods and resultsWe performed post hoc analysis of baseline BP or heart rate and all-cause mortality and cardiovascular events in the SUMMIT trial. SUMMIT was a randomized double-blind outcome trial of 16 485 participants (65 ± 8 years, 75% male, and 47% active smokers) enrolled at 1368 sites in 43 countries. Participants with moderate COPD with or at risk for cardiovascular disease (CVD) were randomized to placebo, long-acting beta agonist, inhaled corticosteroid, or their combination. All-cause mortality increased in relation to high systolic [≥140 mmHg; hazard ratio (HR) 1.27, 95% confidence interval (CI) 1.12-1.45] or diastolic (≥90 mmHg; HR 1.35, 95% CI 1.14-1.59) BP and low systolic (<120 mmHg; HR 1.36, 95% CI 1.13-1.63) or diastolic (<80 mmHg; HR 1.15, 95% CI 1.00-1.32) BP. Higher heart rates (≥80 per minute; HR 1.39, 95% CI 1.21-1.60) and pulse pressures (≥80 mmHg; HR 1.39, 95% CI 1.07-1.80) were more linearly related to increases in all-cause mortality. The risks of cardiovascular events followed similar patterns to all-cause mortality. Similar findings were observed in subgroups of patients without established CVD.ConclusionA 'U-shaped' relationship between BP and all-cause mortality and cardiovascular events exists in patients with COPD and heightened cardiovascular risk. A linear relationship exists between heart rate and all-cause mortality and cardiovascular events in this population. These findings extend the prognostic importance of BP to this growing group of patients and raise concerns that both high and low BP may pose health risks.
| S-EPMC7263699 | biostudies-literature
Project description:Background. To reconcile "the obesity paradox," we tested if (1) the contribution of anthropometric measures to mortality was nonlinear and (2) the confounding of hip circumference contributed to the obesity paradox recently observed among diabetic patients. Methods. We analyzed data of diabetic patients attending a community-based prospective, "Tehran lipid and glucose study." In the mortality analysis, anthropometric measures-body mass index (BMI), waist, and hip circumference-were assessed using Cox models incorporating cubic spline functions. Results. During 12?990 person-years follow-up, BMI levels below 27 and those above 40?kg·m(-2) were associated with increased mortality. When we added waist circumference to the BMI in the multivariate-adjusted model, the steepness of BMI-mortality association curve slope for values below 27?kg·m(-2) increased, whereas the steepness of BMI-mortality association curve slope for values above this threshold decreased. Further adjusting the model for hip circumference, the steepness of the slopes of the association curve moved towards null on both extremes and no associations between BMI and all-cause mortality remained. Conclusion. BMI harbors intermixed positive and negative confounding effects on mortality of waist and hip circumference. Failing to control for the confounding effect of hip circumference may stymie unbiased hazard estimation and render conclusions paradoxical.
| S-EPMC4142289 | biostudies-literature
Project description:Dyspnea, exercise intolerance, and activity restriction are already apparent in mild chronic obstructive pulmonary disease (COPD). However, patients may not seek medical help until their symptoms become troublesome and persistent and significant respiratory impairment is already present; as a consequence, further sustained physical inactivity may contribute to disease progression. Ventilatory and gas exchange impairment, cardiac dysfunction, and skeletal muscle dysfunction are present to a variable degree in patients with mild COPD, and collectively may contribute to exercise intolerance. As such, there is increasing interest in evaluating exercise tolerance and physical activity in symptomatic patients with COPD who have mild airway obstruction, as defined by spirometry. Simple questionnaires, eg, the modified British Medical Research Council dyspnea scale and the COPD Assessment Test, or exercise tests, eg, the 6-minute or incremental and endurance exercise tests can be used to assess exercise performance and functional status. Pedometers and accelerometers are used to evaluate physical activity, and endurance tests (cycle or treadmill) using constant work rate protocols are used to assess the effects of interventions such as pulmonary rehabilitation. In addition, alternative outcome measurements, such as tests of small airway dysfunction and laboratory-based exercise tests, are used to measure the extent of physiological impairment in individuals with persistent dyspnea. This review describes the mechanisms of exercise limitation in patients with mild COPD and the interventions that can potentially improve exercise tolerance. Also discussed are the benefits of pulmonary rehabilitation and the potential role of pharmacologic treatment in symptomatic patients with mild COPD.
| S-EPMC4051517 | biostudies-literature
Project description:ObjectivesThis study sought to determine whether pre-heart failure (HF) myocardial injury explains the differential mortality after HF across weight categories.BackgroundObesity is a risk factor for HF, but pre-HF obesity is associated with lower mortality after incident HF. High-sensitivity cardiac troponin T (hs-cTnT) is a sensitive marker of myocardial injury, and predicts incident HF and mortality.MethodsStratifying 1,279 individuals with incident HF hospitalizations by their pre-HF hs-cTnT levels (< and ≥ 14 ng/l), we examined the association of pre-HF body mass index (BMI) with mortality after incident HF hospitalization in the ARIC (Atherosclerosis Risk In Communities) study.ResultsMean age at HF was 74 years (53% women, 27% black). Individuals with pre-HF hs-cTnT ≥14 ng/l had higher mortality after incident HF (hazard ratio [HR]: 1.46; 95% confidence interval [CI]: 1.18 to 1.80) compared to individuals with hs-cTnT <14 ng/l in an adjusted model including BMI. Compared with normal weight subjects, the mortality was lower in overweight (HR: 0.69, 95% CI 0.48-0.98) and obese individuals (HR: 0.50; 95% CI: 0.35 to 0.72) with hs-cTnT <14 ng/l; and in those with hs-cTnT ≥14 ng/l (overweight HR: 0.50; 95% CI: 0.30 to 0.83; obese HR: 0.56; 95% CI: 0.34 to 0.91; interaction: p = 0.154 between BMI and hs-cTnT). The lower mortality risk in obese and overweight subjects remained similar when log hs-cTnT was added as a continuous variable to a multivariable model, and in sensitivity analyses after further adjusting for left ventricular hypertrophy or high-sensitivity C-reactive protein.ConclusionAlthough greater pre-existing subclinical myocardial injury was associated with higher mortality after incident HF hospitalization, it did not explain the obesity paradox in HF, which was observed irrespective of subclinical myocardial injury. (Atherosclerosis Risk In Communities [ARIC]; NCT00005131).
| S-EPMC5425302 | biostudies-literature
Project description:During the 1930s Dust Bowl drought in the central United States, species with the C3 photosynthetic pathway expanded throughout C4-dominated grasslands. This widespread increase in C3 grasses during a decade of low rainfall and high temperatures is inconsistent with well-known traits of C3 vs. C4 pathways. Indeed, water use efficiency is generally lower, and photosynthesis is more sensitive to high temperatures in C3 than C4 species, consistent with the predominant distribution of C3 grasslands in cooler environments and at higher latitudes globally. We experimentally imposed extreme drought for 4 y in mixed C3/C4 grasslands in Kansas and Wyoming and, similar to Dust Bowl observations, also documented three- to fivefold increases in C3/C4 biomass ratios. To explain these paradoxical responses, we first analyzed long-term climate records to show that under nominal conditions in the central United States, C4 grasses dominate where precipitation and air temperature are strongly related (warmest months are wettest months). In contrast, C3 grasses flourish where precipitation inputs are less strongly coupled to warm temperatures. We then show that during extreme drought years, precipitation-temperature relationships weaken, and the proportion of precipitation falling during cooler months increases. This shift in precipitation seasonality provides a mechanism for C3 grasses to respond positively to multiyear drought, resolving the Dust Bowl paradox. Grasslands are globally important biomes and increasingly vulnerable to direct effects of climate extremes. Our findings highlight how extreme drought can indirectly alter precipitation seasonality and shift ecosystem phenology, affecting function in ways not predictable from key traits of C3 and C4 species.
| S-EPMC7486763 | biostudies-literature
Project description:Emerging literature suggests that obesity may be "protective" against mortality and cardiovascular outcomes, while dysglycemia may worsen outcomes regardless of obesity. The authors measured the association of weight, smoking, and glycemia with mortality in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). Among 5423 ALLHAT participants without established diabetes or cardiovascular disease, 3980 (73%) had normal fasting glucose and 1443 (27%) had impaired fasting glucose (IFG) levels at study entry. After a median of 4.9 years follow-up, 554 (10%) had died (37% cardiovascular). IFG was associated with higher all-cause mortality (adjusted hazard ratio [HR], 1.23; 95% confidence interval [CI], 1.02-1.50), while obesity was associated with lower all-cause mortality (adjusted HR, 0.76; 95% CI, 0.60-0.96). However, after excluding underweight individuals (body mass index [BMI] <22 kg/m(2) ) and smokers, neither obesity nor IFG was associated with all-cause mortality [corrected]. Although obesity appeared protective against mortality, this association was not significant in never-smokers or after exclusion of BMI <22 kg/m(2) . The obesity paradox may result from confounding by a sicker, underweight referent population and smoking.
| S-EPMC4091725 | biostudies-literature