B-type natriuretic peptide is an accurate predictor of heart failure in the emergency department

ABSTRACT

BACKGROUND: B-type natriuretic peptide is released from the cardiac ventricles in response to volume expansion and pressure overload. Levels correlate with severity of congestive heart failure (CHF) and prognosis. A rapid assay for B-type natriuretic peptide might help clinicians’ accuracy in distinguishing CHF from other conditions (eg, chronic obstructive pulmonary disease) as the cause of acute dyspnea in an emergency setting.

POPULATION STUDIED: The investigators enrolled 1586 patients from 7 sites (5 in the United States, 1 in France, 1 in Norway). Eligible subjects (at least 18 years old) presented to the emergency department with shortness of breath for which CHF could not be obviously ruled out (such as in trauma or cardiac tamponade). Patients were not included if they had acute myocardial infarction or renal failure; patients were also not included if they had unstable angina, unless their predominant presenting symptom was dyspnea. Forty-four percent of the subjects were women; 49% were white, 45% were black, and 6% were from other races.

STUDY DESIGN AND VALIDITY: This study evaluated the role B-type natriuretic peptide determinations might play in the diagnosis of CHF by comparing B-type natriuretic peptide levels with clinical diagnosis as the gold standard. Blood was drawn from all included patients for measurement of B-type natriuretic peptide. Emergency room physicians, who were not given the laboratory results, assessed the probability that the patient had CHF. Patients with a history of CHF were classified as having either an exacerbation of CHF or dyspnea from another cause with underlying left ventricular dysfunction.

OUTCOMES MEASURED: Whole blood or plasma levels of B-type natriuretic peptide were measured using a fluorescence immunoassay kit (Triage BNP Test; Biosite Inc, San Diego, CA) and the results were compared with clinical diagnoses to determine the sensitivity, specificity, and accuracy of the test in the diagnosis of CHF. Receiver-operating-characteristic curves were constructed to illustrate various cutoff values of B-type natriuretic peptide. Long-term outcomes of patients with CHF were not measured.

RESULTS: Congestive heart failure was diagnosed in 744 patients (47%), dyspnea due to noncardiac causes in 72 patients with a history of CHF (5%), and no CHF in 770 (48%). The B-type natriuretic peptide level test performed well for diagnosing CHF; the area under the receiver-operating-characteristic curve was 0.91 (where 1.0 indicates a perfect test). A value of 100 pg/mL or more was the single most accurate predictor of the presence of CHF when compared with clinical predictors such as history, physical examination, or chest x-ray. This B-type natriuretic peptide cutoff value of 100 pg/mL was 90% sensitive, 76% specific, and 83% accurate in differentiating CHF from other causes of dyspnea. As such, this cutoff value outperformed the accuracy of 2 commonly used clinical criteria used for diagnosing CHF, the National Health and Nutrition Examination Survey (NHANES) criteria (67%) and Framingham criteria (73%). At this prevalence of 47%, a level of 50 pg/mL was associated with a negative predictive value of 96%. B-type natriuretic peptide values also correlated with CHF severity as determined by the New York Heart Association functional class.

ABSTRACT

BACKGROUND: B-type natriuretic peptide is released from the cardiac ventricles in response to volume expansion and pressure overload. Levels correlate with severity of congestive heart failure (CHF) and prognosis. A rapid assay for B-type natriuretic peptide might help clinicians’ accuracy in distinguishing CHF from other conditions (eg, chronic obstructive pulmonary disease) as the cause of acute dyspnea in an emergency setting.

POPULATION STUDIED: The investigators enrolled 1586 patients from 7 sites (5 in the United States, 1 in France, 1 in Norway). Eligible subjects (at least 18 years old) presented to the emergency department with shortness of breath for which CHF could not be obviously ruled out (such as in trauma or cardiac tamponade). Patients were not included if they had acute myocardial infarction or renal failure; patients were also not included if they had unstable angina, unless their predominant presenting symptom was dyspnea. Forty-four percent of the subjects were women; 49% were white, 45% were black, and 6% were from other races.

STUDY DESIGN AND VALIDITY: This study evaluated the role B-type natriuretic peptide determinations might play in the diagnosis of CHF by comparing B-type natriuretic peptide levels with clinical diagnosis as the gold standard. Blood was drawn from all included patients for measurement of B-type natriuretic peptide. Emergency room physicians, who were not given the laboratory results, assessed the probability that the patient had CHF. Patients with a history of CHF were classified as having either an exacerbation of CHF or dyspnea from another cause with underlying left ventricular dysfunction.

OUTCOMES MEASURED: Whole blood or plasma levels of B-type natriuretic peptide were measured using a fluorescence immunoassay kit (Triage BNP Test; Biosite Inc, San Diego, CA) and the results were compared with clinical diagnoses to determine the sensitivity, specificity, and accuracy of the test in the diagnosis of CHF. Receiver-operating-characteristic curves were constructed to illustrate various cutoff values of B-type natriuretic peptide. Long-term outcomes of patients with CHF were not measured.

RESULTS: Congestive heart failure was diagnosed in 744 patients (47%), dyspnea due to noncardiac causes in 72 patients with a history of CHF (5%), and no CHF in 770 (48%). The B-type natriuretic peptide level test performed well for diagnosing CHF; the area under the receiver-operating-characteristic curve was 0.91 (where 1.0 indicates a perfect test). A value of 100 pg/mL or more was the single most accurate predictor of the presence of CHF when compared with clinical predictors such as history, physical examination, or chest x-ray. This B-type natriuretic peptide cutoff value of 100 pg/mL was 90% sensitive, 76% specific, and 83% accurate in differentiating CHF from other causes of dyspnea. As such, this cutoff value outperformed the accuracy of 2 commonly used clinical criteria used for diagnosing CHF, the National Health and Nutrition Examination Survey (NHANES) criteria (67%) and Framingham criteria (73%). At this prevalence of 47%, a level of 50 pg/mL was associated with a negative predictive value of 96%. B-type natriuretic peptide values also correlated with CHF severity as determined by the New York Heart Association functional class.

ABSTRACT

BACKGROUND: B-type natriuretic peptide is released from the cardiac ventricles in response to volume expansion and pressure overload. Levels correlate with severity of congestive heart failure (CHF) and prognosis. A rapid assay for B-type natriuretic peptide might help clinicians’ accuracy in distinguishing CHF from other conditions (eg, chronic obstructive pulmonary disease) as the cause of acute dyspnea in an emergency setting.

POPULATION STUDIED: The investigators enrolled 1586 patients from 7 sites (5 in the United States, 1 in France, 1 in Norway). Eligible subjects (at least 18 years old) presented to the emergency department with shortness of breath for which CHF could not be obviously ruled out (such as in trauma or cardiac tamponade). Patients were not included if they had acute myocardial infarction or renal failure; patients were also not included if they had unstable angina, unless their predominant presenting symptom was dyspnea. Forty-four percent of the subjects were women; 49% were white, 45% were black, and 6% were from other races.

STUDY DESIGN AND VALIDITY: This study evaluated the role B-type natriuretic peptide determinations might play in the diagnosis of CHF by comparing B-type natriuretic peptide levels with clinical diagnosis as the gold standard. Blood was drawn from all included patients for measurement of B-type natriuretic peptide. Emergency room physicians, who were not given the laboratory results, assessed the probability that the patient had CHF. Patients with a history of CHF were classified as having either an exacerbation of CHF or dyspnea from another cause with underlying left ventricular dysfunction.

OUTCOMES MEASURED: Whole blood or plasma levels of B-type natriuretic peptide were measured using a fluorescence immunoassay kit (Triage BNP Test; Biosite Inc, San Diego, CA) and the results were compared with clinical diagnoses to determine the sensitivity, specificity, and accuracy of the test in the diagnosis of CHF. Receiver-operating-characteristic curves were constructed to illustrate various cutoff values of B-type natriuretic peptide. Long-term outcomes of patients with CHF were not measured.

RESULTS: Congestive heart failure was diagnosed in 744 patients (47%), dyspnea due to noncardiac causes in 72 patients with a history of CHF (5%), and no CHF in 770 (48%). The B-type natriuretic peptide level test performed well for diagnosing CHF; the area under the receiver-operating-characteristic curve was 0.91 (where 1.0 indicates a perfect test). A value of 100 pg/mL or more was the single most accurate predictor of the presence of CHF when compared with clinical predictors such as history, physical examination, or chest x-ray. This B-type natriuretic peptide cutoff value of 100 pg/mL was 90% sensitive, 76% specific, and 83% accurate in differentiating CHF from other causes of dyspnea. As such, this cutoff value outperformed the accuracy of 2 commonly used clinical criteria used for diagnosing CHF, the National Health and Nutrition Examination Survey (NHANES) criteria (67%) and Framingham criteria (73%). At this prevalence of 47%, a level of 50 pg/mL was associated with a negative predictive value of 96%. B-type natriuretic peptide values also correlated with CHF severity as determined by the New York Heart Association functional class.