Clinical Investigation
Hospitalized heart failure: rates and long-term mortality

https://doi.org/10.1016/j.cardfail.2004.02.003Get rights and content

Abstract

Background

Heart failure has been called the “new epidemic of cardiovascular disease,” but few studies have described key epidemiologic measures of the syndrome in geographically defined US populations.

Methods and results

We obtained lists of discharge diagnosis codes in 1995 from 22 Minneapolis-St. Paul metropolitan area hospitals; identified patients 35 to 84 years old with a heart failure discharge code; and sampled and abstracted 50% of the hospital records. To identify heart failure–related hospitalizations, we applied 6 published definitions of the syndrome to the sample and selected cases that met at least 4 of the 6 definitions (n = 2887). The patient cohort was followed for 5 to 6 years to ascertain deaths. The rate of hospitalized heart failure ranged from a few dozen hospitalized patients per 100,000 residents ages 35 to 44 years to more than 2000 per 100,000 residents ages 75 to 84, and was consistently higher among men than among women (age-adjusted rate ratio 1.46; 95% CI 1.39–1.54). Within 1-year of the index admission, 37% of male patients and 30% of female patients have died—10 times the annual mortality of the source population. By the end of the follow-up, cumulative mortality reached 72% in men and 66% in women. In multivariable regression of the hazard of death on age, sex, and left ventricular ejection fraction (LVEF), age was a strong determinant of mortality and male patients had modestly higher hazard of death than female patients (adjusted hazard ratio, 1.29; 95% CI 1.18–1.41). LVEF was not a strong predictor of death.

Conclusion

A heart failure–related hospitalization is a marker of grave prognosis: only one quarter to one third of the patients survives 5 years after admission. Both the risk of hospitalization for heart failure and the risk of subsequent death are moderately higher in men than in women. LVEF, when measured in the context of heart failure–related hospitalization, is not a strong predictor of death.

Section snippets

Study design

We carried out an epidemiologic investigation of hospitalizations involving congestive heart failure among 35- to 84-year-old residents of metropolitan Minneapolis-St. Paul, Minnesota (a total of 7 counties). In 1995, the target year of the survey, the source population comprised 535,778 men and 581,946 women (mostly Caucasians) who were served by 23 hospitals. To identify heart failure–related hospitalizations, we obtained lists of discharge diagnoses, identified relevant heart failure codes (

Results

A total of 5503 hospital records were retrieved and reviewed. Of these, 2092 (38%) represented a previous diagnosis of heart failure with no acute exacerbation, leaving 3411 “possible cases” that were fully abstracted and classified as “heart failure” or “no heart failure” according to each of the 6 algorithms. The proportion of hospitalizations that was classified as “heart failure” ranged from 65% (Rotterdam-based algorithm) to 93% (Framingham-based algorithm). A total of 2887 cases

Discussion

At least 3 methodologic difficulties have challenged attempts to describe the epidemiology of heart failure. First, heart failure is a syndrome—not a morphologically defined pathology. Second, numerous definitions have been proposed for epidemiologic research24., 25., 26. and, as shown here, each definition would lead to a different count of cases. Third, many patients are diagnosed and treated in outpatient clinics, a setting that is less accessible to epidemiologic research than in-hospital

Acknowledgements

We thank Sherri Nooyen, Terri Tharp, and the study nurses for their dedicated work on this study. We thank the participating hospitals in Minneapolis-St. Paul for their long-lasting support of epidemiologic research.

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    Presented in part at the American Heart Association 43rd Annual Conference on Cardiovascular Disease Epidemiology and Prevention, Miami, FL, March 2003.

    Supported by the National, Heart, Lung, and Blood Institute (RO1 HL60959, “Community Surveillance of Congestive Heart Failure”). Dr Kim was supported by a National, Heart, Lung, and Blood Institute training grant (T32HL0779, “Cardiovascular Disease Epidemiology and Prevention”).

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