NZ Trial Shows Value of New Heart Failure Test
21 October 2002
New Zealand Community Trial Shows Value of New Heart Failure Test
A new blood test that indicates if a patient with shortness-of-breath has heart failure has been shown to significantly improve accurate diagnosis of the condition by general practitioners.
That's the conclusion of University of Auckland Faculty of Medical and Health Sciences researcher Sue Wright and a team that investigated the benefits of using the blood test - for a substance called brain natriuretic peptide or BNP - in a primary care setting.
Heightened levels of BNP have been shown by the Christchurch Cardio-Endocrine Research Group, led by Professor Mark Richards, to indicate heart failure.
"Professor Richard's groundbreaking work has led to the development of the BNP test, which has since been trialled in hospital settings," said Dr Wright.
"But the use of BNP for heart failure diagnosis has never before been subjected to a randomised controlled trial in the community.
"Accurate diagnosis and management of heart failure patients by general practitioners is a significant health issue for New Zealand.
"Heart failure affects one in ten people over the age of 70, and is the most common cause of medical admission to Auckland Hospital. It is a chronic, irreversible condition that generally affects older people, causing shortness of breath. Those who have had previous heart attacks or other heart problems are especially at risk of this condition. Heart failure patients need to take long-term medication to control the symptoms.
"As modern medicine helps more and more people survive heart attacks, the incidence of heart failure in later life will probably increase. New Zealand hospital admissions for the condition have increased by 50% over the past ten years.
"Heart failure can be difficult to accurately diagnose. The main symptoms are shortness of breath, and ankle swelling - but these can also indicate other conditions. GPs have to make a diagnosis based on the patient's history and symptoms," said Dr Wright.
That is why Dr Wright and her co-researchers were keen to assess the value of the new BNP test as a first-line test for patients with shortness-of-breath in a controlled trial involving General Practitioners.
"305 patients, all of whom had shortness-of-breath or ankle swelling, agreed to take part in the trial. The average age of the patients was 72 years. After an initial cardiological assessment and a BNP test, the patients were then randomised into two groups. Half the patients were reviewed by GPs who were given the BNP results. The other half formed a control group that was reviewed by GPs using customary clinical assessment without the BNP result.
"We found that the GPs who had access to the BNP result improved their diagnostic accuracy by 21%. Those in the control group, however, achieved only an 8% improvement.
"Interestingly, the increase in accuracy was mainly due to GPs ruling out heart failure. GPs were able to correctly exclude heart failure if the BNP result was normal. The trial results showed that N-BNP improved the diagnostic accuracy of heart failure by GPs when compared to conventional clinical assessment.
"Our study - which was recently presented at the European Society of Cardiology Congress in Berlin - now allows the evidence-based recommendation that availability of brain natriuretic peptide measurement to GPs will significantly improve the diagnostic accuracy of heart failure," said Dr Wright.
Two international diagnostic companies currently offer different forms of the BNP test, but its availability in New Zealand is limited to a few hospitals.
The trial was funded by grants from the Health Research Council of New Zealand and the National Heart Foundation.
For further information contact:
Dr Sue Wright Faculty of Medical and Health Sciences University of Auckland
Ph 09 307 4949 ext 6703
Ellen Strickland Communications Officer Faculty of Medical and Health Sciences University of Auckland
Fiona Stephenson Baldwin Boyle Group PO Box 33886 Takapuna 09 486 6544 025 820 345 email@example.com