Clinical Investigation
Congestive Heart Failure
An obesity paradox in acute heart failure: Analysis of body mass index and inhospital mortality for 108 927 patients in the Acute Decompensated Heart Failure National Registry

https://doi.org/10.1016/j.ahj.2006.09.007Get rights and content

Background

Prior studies on chronic systolic heart failure (HF) have demonstrated that body mass index (BMI) is inversely associated with mortality, the so-called obesity paradox. The aim of this study was to determine whether BMI influences the mortality risk in acute decompensated HF, a subject not previously studied.

Methods

The Acute Decompensated Heart Failure National Registry was analyzed for acute HF hospitalizations in 263 hospitals in the United States from October 2001 through December 2004. Patients with documented height and weight were divided into BMI (measured in kilograms per square meter) quartiles. Inhospital mortality by BMI quartile for all the patients and for those with reduced (n = 43 255) and preserved (n = 37 901) systolic function was assessed.

Results

Body mass index quartiles in the 108 927 hospitalizations were QI (16.0-23.6 kg/m2), QII (23.7-27.7 kg/m2), QIII (27.8-33.3 kg/m2), and QIV (33.4-60.0 kg/m2). Patients in the higher BMI quartiles were younger, had more diabetes, and had a higher left ventricular ejection fraction. Inhospital mortality rates decreased in a near-linear fashion across successively higher BMI quartiles. After adjustments for age, sex, blood urea nitrogen, blood pressure, creatinine, sodium, heart rate, and dyspnea at rest, BMI quartile still predicted mortality risk. For every 5-U increase in BMI, the odds of risk-adjusted mortality was 10% lower (95% CI 0.88-0.93, P < .0001).

Conclusions

In this cohort of hospitalized patients with HF, higher BMI was associated with lower inhospital mortality risk. The relationship between BMI and adverse outcomes in HF appears to be complex and deserving of further study.

Section snippets

Methods

The ADHERE is a national observational registry of hospital data on patients admitted with HF.16 Its design as well as methods and the characteristics of patients included in the ADHERE have been described previously.16 Briefly, medical records are retrospectively reviewed at participating sites by the research coordinator and data from consecutive eligible male and female patients ≥18 years at the time of hospital admission are electronically entered into the registry.16 These data include

Results

From October 2001 through December 2004, there were 155 073 acute HF hospitalization episodes in the ADHERE. Of the patients involved, 46 146 (30%) were excluded from analysis because of missing data on height, weight, or both. Thus, 108 927 acute HF hospitalization episodes of patients with documented height and admission weight were available for analysis. Baseline characteristics between patients with BMI data and those with missing BMI data were similar or showed only modest differences (mean

Discussion

This study demonstrates that increased BMI is associated with a significantly lower risk for inhospital mortality among patients hospitalized with acute HF. This relationship was independent of other known prognostic factors and persisted in hospitalized patients with HF who have both reduced and preserved systolic function. By weight category, patients who were overweight and obese had mortality risks that were 26.1% and 47.8%, respectively, lower as compared with the mortality risk of healthy

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The Acute Decompensated Heart Failure National Registry and this study were funded by Scios, Inc (Freemont, CA).

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