Variation by race in factors contributing to heart failure hospitalizations

Racial/Ethnic Differences in 30-Day Mortality for Heart Failure and Pneumonia in the Veterans Health Administration Using Claims-based, Clinical, and Social Risk-adjustment Variables

BACKGROUND

Prior studies have identified lower mortality in Black Veterans compared with White Veterans after hospitalization for common medical conditions, but these studies adjusted for comorbid conditions identified in administrative claims.

OBJECTIVES

The objectives of this study were to compare mortality for non-Hispanic White (hereafter, "White"), non-Hispanic Black (hereafter, "Black"), and Hispanic Veterans hospitalized for heart failure (HF) and pneumonia and determine whether observed mortality differences varied according to whether claims-based comorbid conditions and/or clinical variables were included in risk-adjustment models.

RESEARCH DESIGN

This was an observational study.

SUBJECTS

The study cohort included 143,520 admissions for HF and 127,782 admissions for pneumonia for Veterans hospitalized in 132 Veterans Health Administration (VA) Medical Centers between January 2009 and September 2015.

MEASURES

The primary independent variable was racial/ethnic group (ie, Black, Hispanic, and non-Hispanic White), and the outcome was all-cause mortality 30 days following admission. To compare mortality by race/ethnicity, we used logistic regression models that included different combinations of claims-based, clinical, and sociodemographic variables. For each model, we estimated the average marginal effect (AME) for Black and Hispanic Veterans relative to White Veterans.

RESULTS

Among the 143,520 (127,782) hospitalizations for HF (pneumonia), the average patient age was 71.6 (70.9) years and 98.4% (97.1%) were male. The unadjusted 30-day mortality rates for HF (pneumonia) were 7.2% (11.0%) for White, 4.1% (10.4%) for Black and 8.4% (16.9%) for Hispanic Veterans. Relative to White Veterans, when only claims-based variables were used for risk adjustment, the AME (95% confidence interval) for the HF [pneumonia] cohort was -2.17 (-2.45, -1.89) [0.08 (-0.41, 0.58)] for Black Veterans and 1.32 (0.49, 2.15) [4.51 (3.65, 5.38)] for Hispanic Veterans. When clinical variables were incorporated in addition to claims-based ones, the AME, relative to White Veterans, for the HF [pneumonia] cohort was -1.57 (-1.88, -1.27) [-0.83 (-1.31, -0.36)] for Black Veterans and 1.50 (0.71, 2.30) [3.30 (2.49, 4.11)] for Hispanic Veterans.

CONCLUSIONS

Compared with White Veterans, Black Veterans had lower mortality, and Hispanic Veterans had higher mortality for HF and pneumonia. The inclusion of clinical variables into risk-adjustment models impacted the magnitude of racial/ethnic differences in mortality following hospitalization. Future studies examining racial/ethnic disparities should consider including clinical variables for risk adjustment.

Cardiac mesenchymal cells from diabetic mice are ineffective for cell therapy-mediated myocardial repair

Although cell therapy improves cardiac function after myocardial infarction, highly variable results and limited understanding of the underlying mechanisms preclude its clinical translation. Because many heart failure patients are diabetic, we examined how diabetic conditions affect the characteristics of cardiac mesenchymal cells (CMC) and their ability to promote myocardial repair in mice. To examine how diabetes affects CMC function, we isolated CMCs from non-diabetic C57BL/6J (CMCWT) or diabetic B6.BKS(D)-Leprdb/J (CMCdb/db) mice. When CMCs were grown in 17.5 mM glucose, CMCdb/db cells showed > twofold higher glycolytic activity and a threefold higher expression of Pfkfb3 compared with CMCWT cells; however, culture of CMCdb/db cells in 5.5 mM glucose led to metabolic remodeling characterized by normalization of metabolism, a higher NAD+/NADH ratio, and a sixfold upregulation of Sirt1. These changes were associated with altered extracellular vesicle miRNA content as well as proliferation and cytotoxicity parameters comparable to CMCWT cells. To test whether this metabolic improvement of CMCdb/db cells renders them suitable for cell therapy, we cultured CMCWT or CMCdb/db cells in 5.5 mM glucose and then injected them into infarcted hearts of non-diabetic mice (CMCWT, n = 17; CMCdb/db, n = 13; Veh, n = 14). Hemodynamic measurements performed 35 days after transplantation showed that, despite normalization of their properties in vitro, and unlike CMCWT cells, CMCdb/db cells did not improve load-dependent and -independent parameters of left ventricular function. These results suggest that diabetes adversely affects the reparative capacity of CMCs and that modulating CMC characteristics via culture in lower glucose does not render them efficacious for cell therapy.

Type 2 Diabetes Dysregulates Glucose Metabolism in Cardiac Progenitor Cells

Type 2 diabetes is associated with increased mortality and progression to heart failure. Recent studies suggest that diabetes also impairs reparative responses after cell therapy. In this study, we examined potential mechanisms by which diabetes affects cardiac progenitor cells (CPCs). CPCs isolated from the diabetic heart showed diminished proliferation, a propensity for cell death, and a pro-adipogenic phenotype. The diabetic CPCs were insulin-resistant, and they showed higher energetic reliance on glycolysis, which was associated with up-regulation of the pro-glycolytic enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3). In WT CPCs, expression of a mutant form of PFKFB, which mimics PFKFB3 activity and increases glycolytic rate, was sufficient to phenocopy the mitochondrial and proliferative deficiencies found in diabetic cells. Consistent with activation of phosphofructokinase in diabetic cells, stable isotope carbon tracing in diabetic CPCs showed dysregulation of the pentose phosphate and glycero(phospho)lipid synthesis pathways. We describe diabetes-induced dysregulation of carbon partitioning using stable isotope metabolomics-based coupling quotients, which relate relative flux values between metabolic pathways. These findings suggest that diabetes causes an imbalance in glucose carbon allocation by uncoupling biosynthetic pathway activity, which could diminish the efficacy of CPCs for myocardial repair.

Glutamine Regulates Cardiac Progenitor Cell Metabolism and Proliferation

Autologous transplantation of cardiac progenitor cells (CPCs) alleviates myocardial dysfunction in the damaged heart; however, the mechanisms that contribute to their reparative qualities remain poorly understood. In this study, we examined CPC metabolism to elucidate the metabolic pathways that regulate their proliferative capacity. In complete growth medium, undifferentiated CPCs isolated from adult mouse heart proliferated rapidly (Td  = 13.8 hours). CPCs expressed the Glut1 transporter and their glycolytic rate was increased by high extracellular glucose (Glc) concentration, in the absence of insulin. Although high Glc concentrations did not stimulate proliferation, glutamine (Gln) increased CPC doubling time and promoted survival under conditions of oxidative stress. In comparison with Glc, pyruvate (Pyr) or BSA-palmitate, Gln, when provided as the sole metabolic substrate, increased ATP-linked and uncoupled respiration. Although fatty acids were not used as respiratory substrates when present as a sole carbon source, Gln-induced respiration was doubled in the presence of BSA-palmitate, suggesting that Gln stimulates fatty acid oxidation. Additionally, Gln promoted rapid phosphorylation of the mTORC1 substrate, p70S6k, as well as retinoblastoma protein, followed by induction of cyclin D1 and cdk4. Inhibition of either mTORC1 or glutaminolysis was sufficient to diminish CPC proliferation, and provision of cell permeable α-ketoglutarate in the absence of Gln increased both respiration and cell proliferation, indicating a key role of Gln anaplerosis in cell growth. These findings suggest that Gln, by enhancing mitochondrial function and stimulating mTORC1, increases CPC proliferation, and that interventions to increase Gln uptake or oxidation may improve CPC therapy.

Comparison across races of peak oxygen consumption and heart failure survival score for selection for cardiac transplantation

The aim of the present study was to determine whether peak oxygen consumption (VO(2)) and the Heart Failure Survival Score (HFSS) predict prognosis in European-American, African-American, and Hispanic-American patients with chronic heart failure referred for heart transplantation. The peak VO(2) and the HFSS have previously been shown to effectively risk stratify patients with chronic heart failure and are criteria for the listing for heart transplantation. However, the effect of race on the predictive value of these variables has not been studied. A total of 715 patients with congestive heart failure (433 European American, 126 African American, 123 Hispanic American, and 33 other), who had been referred for heart transplantation, underwent cardiopulmonary exercise testing with measurement of the peak VO(2) and calculation of the HFSS. A total of 354 patients had died or undergone urgent heart transplantation or implantation of a left ventricular assist device during the 962 +/- 912 days of follow-up. On univariate and multivariate Cox hazard analysis, both peak VO(2) and the HFSS were powerful prognostic markers in the overall cohort and in the separate races. In the receiver operating characteristic curve analysis, the areas under the curve at 1 and 2 years of follow-up were greater for the HFSS than for peak VO(2). In conclusion, HFSS and peak VO(2) can be used for transplant selection; however, in the era of modern therapy and across races and genders, the HFSS might perform better than the peak VO(2).

Mortality after hospitalization for heart failure in blacks compared to whites

Heart failure (HF) disproportionately affects black compared to white Americans, and overall mortality from HF is greater among blacks. Paradoxically, mortality rates after a hospitalization for HF are lower in black than in white patients. These racial differences might reflect hospital, physician, and patient factors and could have implications for comparative hospital profiles. We identified published studies reporting the posthospitalization mortality for black and white patients with a discharge diagnosis of HF and conducted random-effects meta-analyses with the outcome of all-cause mortality. We included 29 cohorts of hospitalized black and white patients with HF. The unadjusted mean mortality rate after HF hospitalization for black and white patients, respectively, was 6% and 9% for in-hospital, 6% and 10% for 30-day, 10% and 15% for 60- to 180-day, 28% and 34% for 1-year, and 41% and 47% for >1-year follow-up, respectively. The unadjusted combined odds ratios for mortality in black versus white patients ranged from 0.48 for in-hospital (95% confidence interval [CI] 0.45 to 0.51) to 0.77 after >1 year follow-up (95% CI 0.75 to 0.79). In meta-analyses using adjusted data, the combined odds ratio was 0.68 for short-term mortality (95% CI 0.63 to 0.74), and the combined hazard ratio was 0.84 for long-term mortality (95% CI 0.77 to 0.91). In conclusion, mortality after hospitalization for HF was 32% lower during short-term follow-up and 16% lower during long-term follow-up for black than for white patients. The mortality differences imply unmeasured differences by race in clinical severity of illness at hospital admission and might lead to biased hospital mortality profiles.

Characteristics associated with racial disparities in illness beliefs of patients with heart failure

African Americans have greater misperceptions about heart failure (HF) than Caucasians. We examined socioeconomic and medical history factors to determine if they explain differences in accuracy of HF illness beliefs by race. 519 patients completed an illness beliefs and socioeconomic status survey. After establishing univariate associations by race, linear regression with backward selection was used to identify factors associated with HF illness beliefs accuracy. HF illness beliefs were less accurate among African Americans (p < .01). In multivariate models, race remained a predictor of HF illness beliefs accuracy, as did education level and living status (all ps < or = .01). Illness beliefs of African Americans were inaccurate and independently associated with social support and education level. Health care providers must consider patient education processes as a possible cause of differences and focus on what and how they teach, literacy level, materials used, and family engagement and education.

Utility of the Seattle Heart Failure Model in patients with advanced heart failure

OBJECTIVES

The aim of this study was to validate the Seattle Heart Failure Model (SHFM) in patients with advanced heart failure (HF).

BACKGROUND

The SHFM was developed primarily from clinical trial databases and extrapolated the benefit of interventions from published data.

METHODS

We evaluated the discrimination and calibration of SHFM in 445 advanced HF patients (age 52 +/- 12 years, 68.5% male, 52.4% white, ejection fraction 18 +/- 8%) referred for cardiac transplantation. The primary end point was death (n = 92), urgent transplantation (n = 14), or left ventricular assist device (LVAD) implantation (n = 3); a secondary analysis was performed on mortality alone.

RESULTS

Patients were receiving optimal therapy (angiotensin-II modulation 92.8%, beta-blockers 91.5%, aldosterone antagonists 46.3%), and 71.0% had an implantable device (defibrillator 30.4%, biventricular pacemaker 3.4%, combined 37.3%). During a median follow-up of 21 months, 109 patients (24.5%) had an event. Although discrimination was adequate (c-statistic >0.7), the SHFM overall underestimated absolute risk (observed vs. predicted event rate: 11.0% vs. 9.2%, 21.0% vs. 16.6%, and 27.9% vs. 22.8% at 1, 2, and 3 years, respectively). Risk underprediction was more prominent in patients with an implantable device. The SHFM had different calibration properties in white versus black patients, leading to net underestimation of absolute risk in blacks. Race-specific recalibration improved the accuracy of predictions. When analysis was restricted to mortality, the SHFM exhibited better performance.

CONCLUSIONS

In patients with advanced HF, the SHFM offers adequate discrimination, but absolute risk is underestimated, especially in blacks and in patients with devices. This is more prominent when including transplantation and LVAD implantation as an end point.

Differences in initial severity of illness between black and white emergency department patients hospitalized with heart failure

BACKGROUND

Black patients hospitalized for heart failure have better reported short-term survival than white patients for unknown reasons. We sought to determine if initial severity of illness differed between black and white emergency department (ED) patients hospitalized for heart failure.

METHODS

We analyzed 1,408 black and 7,260 white randomly selected patients in one state hospitalized from an ED during 2003 and 2004 and with a discharge diagnosis of heart failure. We used three validated clinical prediction rules to estimate severity of illness on admission.

RESULTS

Black patients were younger than white patients (65.8 +/- 14.8 vs 77.4 +/- 11.5 years, P < .01) and were assigned to lower risk classes by all 3 prediction rules more frequently than white patients (P < .01). The odds ratio (95% CI) for classification of black versus white patients into the lowest risk class within the three rules ranged from 1.16 (1.00-1.33) to 4.30 (3.75-4.94). After adjusting for hospital clustering, the odds ratio (95% CI) for black versus white patient hospital death and complications was 0.75 (0.60-0.95) and, for 30-day death, was 0.34 (0.27-0.48).

CONCLUSIONS

Black ED patients hospitalized with heart failure are younger, less severely ill on admission and less likely to experience short-term fatal and nonfatal outcomes than white patients. Our findings suggest a varying opportunity between black and white patients when considering alternative initial treatment strategies and sites of care.

Race-related differences in heart failure therapies: simply black and white or shades of grey?

The magnitude of burden imposed by heart failure on society has necessitated the evolution of innovative strategies to identify specific avenues of treatment and the populations at highest risk. Multiple studies have demonstrated a higher burden of cardiovascular disease in black Americans. It has also been shown that the clinical characteristics of heart failure, therapeutic targets, and response to various treatment modalities, are different in blacks as compared with whites. This article explores the unique race-related differences in heart failure with particular emphasis on the currently recommended therapeutic agents in heart failure.

Racial variations in quality of care and outcomes in an ambulatory heart failure cohort

BACKGROUND

Few recent studies have demonstrated similar quality of care for hospitalized black and white patients with heart failure (HF). However, systematic evaluation of racial differences in both the quality of care and outcomes is needed in the outpatient setting, where most patients with HF are treated and where care may be more fragmented.

METHODS

We examined racial differences in quality-of-care measures and outcomes of 1-year mortality and hospitalization in a national cohort of 18,611 ambulatory patients with HF treated at Veterans Affairs medical centers between October 2000 and September 2002.

RESULTS

Black patients were more likely to have left ventricular ejection fraction assessment than whites (risk-adjusted OR 1.29, 95% CI 1.11-1.49). In patients with left ventricular ejection fraction <40%, blacks were as likely as whites to be on treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (risk-adjusted OR 1.06, 95% CI 0.85-1.33) and beta-blockers (risk-adjusted OR 0.92, 95% CI 0.79-1.07). However, black patients more frequently had uncontrolled hypertension and were more likely to be hospitalized for any cause (OR 1.20, 95% CI 1.08-1.33) or for HF (OR 1.43, 95% CI 1.23-1.66), although 1-year mortality did not differ by race (OR 1.03, 95% CI 0.89-1.20).

CONCLUSIONS

In a financially "equal access" health care system, the quality of outpatient HF care assessed by select quality measures and 1-year mortality was similar in black compared to white patients. However, blacks were more likely to be hospitalized, especially with HF. Identifying and targeting potentially modifiable factors such as uncontrolled hypertension in black patients may narrow the racial gap in hospitalizations.