Diagnosing Heart Failure in Primary Care

Abstract

The aim of this thesis is to assess diagnostic strategies in patients suspected of heart failure (defined as a syndrome in which patients suffer from the inability of the heart to supply sufficient blood flow to meet the needs of the body) in primary care. B-type Natriuretic Peptide (BNP or NT-proBNP, a blood sample measurement) is used as a leverage to assess diagnostic strategies encompassing besides BNP other diagnostic tests as well, with special emphasis on physical examination. Diagnostic research is about using the appropriate patient domain: patients suspected of the disease. And diagnostic research is about multivariable hierarchical tests resulting in an estimated probability of presence of disease. A new diagnostic test should have additional value on top of the other tests usually performed, including history taking and physical examination. In the main study, the Utrecht Heart Failure Organisation – Initial Assessment (UHFO-IA) study, data were collected of 721 patients with suspected heart failure After referral 207 (28.7%) were categorized as having heart failure and 514 as not (yet). A diagnostic rule, based on signs and symptoms, the patient’s medical history and the plasma NT-proBNP test, was derived to help general practitioners decide whether the patient has heart failure. The UHFO rule includes 10 items: age; history of myocardial infarction, CABG or PCI; using a loop diuretic; displaced apex beat; pulmonary rales; irregular pulse; pulse rate; heart murmur; elevated jugular venous pressure and the NT-proBNP level. The rule output is an estimated probability of heart failure present. This study estimated the quantitative diagnostic contribution of elements of the history and physical examination in the diagnosis of heart failure in primary care patients, and may help to improve clinical decision making. The largest additional quantitative diagnostic contribution to those elements was provided by NT-proBNP. The UHFO rule was assessed with respect to cost-effectiveness. Application of UHFO rule based diagnostic strategies are explored over the full course of the patient, starting from being suspected of the disease, being diagnosed timely or later, being treated and experiencing the vicious nature of heart failure, frequently experiencing hospital admissions until an often early death. it is cost effective to apply the UHFO diagnostic rule to arrive at one of three outcomes: 1) heart failure probably not present (probability 80%); start treatment and 3) diagnostic uncertainty remains; refer for cardiology consultation. In the general discussion it is argued that diagnostic studies assessing the value of items from physical examination in suspected heart failure, but also in other suspected diseases, have been too small and often lacked a valid study design. As a consequence, these studies tend to discredit solitary elements of the physical examination. The plea is made to perform large descriptive studies in the relevant patient domain, optimally designed to study the value of diagnostic tests, including findings from physical examination.