New Diagnostic Strategies in Heart Failure - Project description
Background
Patients with clinical signs and symptoms of heart failure usually present first to their primary care physician (general practitioner, GP). However, the differential diagnosis is often difficult, in particular in the elderly, and a definitive diagnosis can often only be reached by a specialist with more sophisticated diagnostic tools at hands. Several studies revealed a surprisingly low rate of diagnostic accuracy regarding heart failure when only symptoms and clinical signs were used as diagnostic criteria. Usually GPs have no means to visualize and assess cardiac function, such as by a handheld echocardiography device (ECHO). The determination of natriuretic peptides (BNP) as a point-of-care test has become available only recently, and GPs are neither used to the interpretation of the test results nor is information available on the cost-effectiveness and diagnostic value of this test in diagnostically naïve symptomatic patients with suspected heart failure in a primary care setting. Thus, a large randomized trial was set up to clarify feasibility and benefit of these diagnostic methods if applied in primary care.
Objective
The objective of the first study of subproject 6 – the Handheld BNP Study – was to carry out a study aiming to improve the diagnosis of heart failure in the setting of primary care. In cooperation with the University Hospital of Essen, the Coordinating Center for Clinical Trials in Leipzig, 12 cardiologists and 48 GPs the feasibility and diagnostic yield of ECHO and BNP regarding the differential diagnosis of heart failure signs and symptoms in diagnostically naïve primary care patients was tested. In a follow-up study, the prognostic value of the initially obtained data and measurements is currently investigated.
Implementation
Training study: As a first step,, a structured program designed to train GPs in the use and interpretation of ECHO and a point-of-care test for BNP was developed and evaluated in a two-center trial also regarding supra-regional reproducibility. The primary end point of this study was the expert time required to enable the GPs to achieve the correct diagnosis (confirmation or exclusion of heart failure) in at least 80% of cases. The study revealed that GPs required at both sites approximately 5 hours theoretical and practical training to reach this goal.
Screening study: A cluster-randomized four-arm design was employed in which each cardiologist cooperated with 4 GPs. Patient recruitment was completed in June 2008. A total of 922 patients (63.5% female) were enrolled in the study. Due to 76 dropouts, the data of 846 patients have been entered in the database for further analysis after an extensive data cleaning and query management process. The results of this paper are expected in February 2009.
Follow-up: The first follow-up of the patients is performed 2 years after the inclusion in the diagnostic trial. Further follow-ups are planned in 2-year intervals. Long-term data outcome assessment will allow to also assess the prognostic value of the variables measured at baseline. In addition, novel biomarkers will be tested in blood samples stored in the bank of biomaterials regarding their diagnostic potential in this particular patient population. These results are urgently needed as information on the value of biomarkers in a decompensated state of heart failure are amply available, but data in clinically stable patients with only mild symptoms are scarce.
Added value via networking
The competence network facilitated establishment of a long-term administrative office enabling the generation of ambitious multicentre trials. The local diagnostic networks generated for the purpose of this trial enabled recruitment of the worldwide largest patient sample ever included in a primary care diagnostic heart failure study. This should allow valid statistical analyses and facilitate reliable statements regarding the potential added value of BNP and handheld echo when used in primary care.