The REFer for EchocaRdiogram study: a prospective validation of a clinical decision rule in the diagnosis of heart failure
Heart failure is a chronic disease associated with significant mortality and poor quality of life for patients. Making an accurate and timely diagnosis is crucial and requires referral for objective testing but deciding who to refer can be challenging. The aim of this study was to evaluate the performance of a clinical decision rule (CDR), with or without natriuretic peptide assay, for identifying heart failure in symptomatic patients presenting to primary care.
Prospective, observational, diagnostic validation study of patients over the age of 55 years, presenting with recent, new onset shortness of breath, lethargy or ankle oedema over 48 hours duration from 28 general practices in the United Kingdom. Outcome was test performance of the CDR and natriuretic peptide test in determining a diagnosis of heart failure. The reference standard was an expert consensus panel of three cardiologists.
304 participants were recruited; mean age 73.9 years (SD 9.0) and 180 (59.2%) were female. 104 (34.2% (95% CI 28.9 to 39.8)) had a confirmed diagnosis of heart failure. The CDR had a sensitivity of 90% (95% CI 83% to 95%) and specificity 46% (39% to 53%). NT-proBNP level alone with a cut-off less than 400pg/ml, had sensitivity 77% (68% to 85%) and specificity 92% (87% to 95%). At the lower cut-off of 125pg/ml, sensitivity was 94% (95% CI 88% to 98%) and specificity 49% (42% to 56%).
Natriuretic peptide testing alone performed as well as the validated CDR in determining which patients presenting with symptoms went on to have a diagnosis of heart failure. The current NT-proBNP cut-off level of 400pg/ml used in the United Kingdom is too high and means one in five patients with heart failure may not be appropriately referred for further investigation and diagnosis.