ABSTRACT
Background: Insufficient data exists regarding the relationship between body mass index (BMI) and the prognosis of chronic heart failure (CHF) specifically within low- and middle-income Asian countries. The objective of this study was to evaluate the impact of BMI on adverse outcomes of ambulatory patients with CHF in Vietnam. Methods: Between 2018 and 2020, we prospectively enrolled consecutive outpatients with clinically stable CHF in an observational cohort, single-center study. The participants were stratified according to Asian-specific BMI thresholds. The relationships between BMI and adverse outcomes (all-cause death and all-cause hospitalization) were analyzed by Kaplan-Meier survival curves and Cox proportional-hazards model. Results: Among 320 participants (age 63.5 ± 13.3 years, 57.9% male), the median BMI was 21.4 kg/m2 (IQR 19.5-23.6), and 10.9% were underweight (BMI <18.50 kg/m2). Over a median follow-up time of 32 months, the cumulative incidence of all-cause mortality and hospitalization were 5.6% and 19.1%, respectively. After multivariable adjustment, underweight patients had a significantly higher risk of all-cause mortality than patients with normal BMI (adjusted hazard ratios = 3.03 [95% CI: 1.07-8.55]). Lower BMI remained significantly associated with a worse prognosis when analyzed as a continuous variable (adjusted hazard ratios = 1.27 [95% CI: 1.03-1.55] per 1 kg/m2 decrease for all-cause mortality). However, BMI was not found to be significantly associated with the risk of all-cause hospitalization (p > 0.05). Conclusion: In ambulatory patients with CHF in Vietnam, lower BMI, especially underweight status (BMI < 18.5 kg/m2), was associated with a higher risk of all-cause mortality. These findings suggest that BMI should be considered for use in risk classification, and underweight patients should be managed by a team consisting of cardiologists, nutritionists, and geriatricians.
ABSTRACT
We present a combined experimental and computational study of the effect of charge doping in the osmium based double perovskite Ba2Na1-x Ca x OsO6 for 0 ≤ x ≤ 1 in order to provide a structural and electronic basis for understanding this complex Dirac-Mott insulator material. Specifically, we investigate the effects of the substitution of monovalent Na with divalent Ca, a form of charge doping or alloying that nominally tunes the system from Os7+ with a 5d1 configuration to Os6+ with 5d2 configuration. After an X-ray diffraction characterization, the local atomic and electronic structure has been experimentally probed by X-ray absorption fine structure at all the cation absorption edges at room temperature; the simulations have been performed using ab initio density functional methods. We find that the substitution of Na by Ca induces a linear volume expansion of the crystal structure which indicates an effective alloying due to the substitution process in the whole doping range. The local structure corresponds to the expected double perovskite one with rock-salt arrangement of Na/Ca in the B site and Os in the B' one for all the compositions. X-ray absorption near edge structure measurements show a smooth decrease of the oxidation state of Os from 7+ (5d1) to 6+ (5d2) with increasing Ca concentration, while the oxidation states of Ba, Na, and Ca are constant. This indicates that the substitution of Na by Ca gives rise to an effective electron transfer from the B to the B' site. The comparison between X-ray absorption measurements and ab initio simulations reveals that the expansion of the Os-O bond length induces a reduction of the crystal field splitting of unoccupied Os derived d states.
