Biosite plans to file a 510(k) application in mid-2003 seeking a therapeutic monitoring indication for its Triage B-type natriuretic peptide (BNP) test to aid in diagnosis of congestive heart failure.

The submission will include data from the seven-site, 1,000-patient Rapid Emergency Diagnosis Heart Failure Outpatient trial (REDHOT), which commenced in 2001. As of April 1, 50% of patients were enrolled.

The new indication would open up a much larger market for the product. According to the firm, at least 5 mil. patients each year are candidates for therapeutic use of the test. The overall BNP platform could eventually have a U.S. market potential of over $250 mil., the firm says.

The point-of-care test was first approved in 2000 for use in hospital emergency departments and heart failure clinics (¹ Also see "Biosite Triage BNP Heart Failure Blood Test Has 84.4% Sensitivity" - Medtech Insight, 4 December, 2000., p. 15). The test, which takes 15 minutes to complete, measures circulating levels of BNP taken from a blood sample. BNP levels are elevated during heart dysfunction in both symptomatic (late-stage) and asymptomatic (early-stage) CHF patients.

In addition to a therapeutic indication, the firm is also pursuing use of the test for risk stratification of patients with acute coronary syndrome. The firm has conducted a 2,025-patient sample study, the results of which will be included in a 510(k) application for the indication, the firm says. No target submission date has been identified.

BNP testing could ultimately be used to predict future cardiac events, an editorial appearing in the July 18 New England Journal of Medicine suggests.

Further, BNP levels could be used to "confirm the diagnosis of congestive heart failure; to measure the severity of left ventricular compromise; to quantify the functional class...and to evaluate the efficacy of therapy for heart failure," Kenneth Baughman, MD, Johns Hopkins Hospital, opines.

Baughman's predictions are based on results from the Breathing Not Proper study, published in the same NEJM issue, which confirms the value of BNP levels in the diagnosis of CHF by demonstrating an association between BNP concentration in the circulation and CHF severity.

Study investigators took note of physicians' pre-test judgements as to whether patients who presented with shortness of breath had CHF. Results showed physicians were clinically uncertain in their diagnosis of CHF in 43% of the patients; however, by augmenting clinical judgement with a BNP test, the uncertainty was reduced to 11%.

"In the study, BNP was the single most accurate predictor of [CHF]," lead study author Alan Maisel, MD, San Diego VA Healthcare System, noted in a July 18 release. "BNP performed better than both the National Health and Nutrition and Examination Survey (NHANES) and the Framingham criteria."

Results of the study showed the blood test to be 83% accurate when used alone, compared with a rate of 73% and 67% for NHANES and Framingham criteria, respectively. "The study demonstrates that even without physician input, the BNP test offers a higher degree of correct and quick diagnosis," Maisel noted.

The seven-center study is the first prospective, blinded international trial to examine the use of BNP as a test to evaluate emergency room patients who are short of breath.

Of the 1,586 participants, 744 patients (47%) had a final diagnosis of CHF, 72 patients (5%) had a history of CHF but their shortness of breath was due to non-cardiac causes and 770 patients (49%) did not have CHF. Patients ranged in age from 18-105 years. Roughly half were female.

"It appears that while blood tests for cardiac markets...have become essential to the diagnosis of a heart attack, the BNP blood test has now become integral to the diagnosis of CHF," Maisel concluded.

The Triage test lists at $26 and is run on a meter costing $4,600. Currently, the test is reimbursed at $18 under the inpatient prospective payment system (IPPS) general code for immunoassays. Biosite plans to apply for a separate CPT code for BNP. That code could be approved in time for the FY 2004 IPPS update, the firm anticipates.

Separately, Biosite plans to file a PMA submission in 2003 for use of its Triage meter platform with markers to detect stroke in acute care settings. A 600-patient sample prospective study found six stroke markers to be more than two times as sensitive as CT scans in detecting ischemic stroke (² Also see "Biosite Aiming For Stroke Diagnostic PMA Submission In 2003" - Medtech Insight, 13 August, 2001., p. 12). Human clinical studies are expected to begin in the fourth quarter, Biosite says.

Biosite Triage BNP Reduces Diagnosis Uncertainty To 11%, NEJM Study Finds

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