Barcelona, 3 September 2006:
Approximately 1% of the general population in Europe has symptomatic heart failure and the prevalence increases. The prognosis is as poor as in many cancer forms. Effective treatment is available, but is not offered to many patients as they are not diagnosed correctly.
We found the NT-proBNP test was effective in ruling out heart failure, when the general practitioner suspected heart failure.
Heart failure is a combination of symptoms and objective findings of ‘cardiac dysfunction’ according to the European Society of Cardiology (ESC) guidelines. Ultrasound examination of the heart, echocardiography, is widely accepted as an objective diagnostic tool in characterizing cardiac dysfunction. Echocardiography is a relatively expensive and often limited resource.
When it comes to heart failure, clinical examination alone is an inaccurate diagnostic approach. The general practitioner needs a simple, inexpensive tool to identify patients for further investigations.
Therefore we evaluated the NT-proBNP test performance before and after introduction in general practice.
When the heart muscle cell is stretched, as in heart failure, the cardiac peptide, NT-proBNP, is released into the blood stream. Patients with heart failure have increased blood levels of NT-proBNP. In addition, the worse the disease, the higher NT-proBNP-level. ESC guidelines on heart failure introduced the diagnostic usefulness of NT-proBNP and related peptides in 2005.(1)
We chose to evaluate the NT-proBNP test at the cut-off point 125 ng/l as recommended by the company (Roche Diagnostics) in Europe.
We examined a sample of 367 referred patients suspected to suffer from heart failure prior to the introduction of the NT-proBNP test (Group 2). Only 9% percent had true heart failure as judged by echocardiography. The percentage of positive NT-proBNP tests in Group 2 was 57%.(2)
The proportion of referred patients with true heart failure doubled, (to 21%), following introduction of the NT-proBNP test (Group 1, 517 patients). Furthermore, the proportion of positive NT-proBNP tests rose to 87%. The latter reflects the positive effect on patient referral to echocardiography due to the introduction of the NT-proBNP test. The general practitioners were not specifically instructed to refer patients with a certain NT-proBNP for echocardiography but could use the test result, as they considered appropriate. In Group 1, the lowest registered NT-proBNP value in patients with true heart failure was 127 ng/l. In other words, no patients with true heart failure were missed underlining the strength of the NT-proBNP test as an effective rule-out test.
Assuming the prices of an echocardiography and a NT-proBNP test are €150 and €22.50, respectively, a cost-benefit analysis on the introduction of the NT-proBNP test in primary care shows a reduction in the diagnostic expenses of €21 per patient.
In conclusion:
- Measurement of the cardiac peptide, NT-proBNP, in general practice is a useful rule-out test for heart failure when using a cut-off point of 125 ng/l lending support to the ESC guidelines
- We believe the introduction of NT-proBNP as a rule-out test in primary care will improve the time-to-diagnosis and thereby time-to-treatment which is crucial to patient survival and well-being
- The implementation of the NT-proBNP test in general practice saved unnecessary echocardiographies
- A NT-proBNP guided diagnostic approach reduced the expenditure by €21 per patient in our setting