Identification of the minimal important change in NT-proBNP Levels over one year in octogenarians in Belgium

Details

Supervisors

Degryse, Jean-Marie

Faculty

Faculté de santé publique

Degree label

Master [120] en sciences de la santé publique, à finalité spécialisée

Abstract

Background and purpose: Heart failure(HF) is a major clinical and public health challenge and is considered as an important disease of the elderly accounting for 10.5% in individuals ≥ 65 years, and around 20.0% in population ≥ 75 years. Its prevalence approximately doubles with each decade of life; as people live longer, the occurrence of HF rises as well as others diseases of old age that mimic the symptoms of HF, complicating its diagnosis. The diagnosis is not always simple because HF symptoms are often non-specific making it difficult to differentiate between HF and other diseases usually common in elderly people. NT-proBNP and echocardiography are widely used for the diagnosis and prognosis of HF, however, NT-ProBNP levels increase with age, even in patients without heart failure, which may complicate the use in elderly patients. Higher reference limits of NT-proBNP have been proposed in elderly patient and its concentrations are thought to be useful in identifying elderly patients at higher risk for HF, including hospitalization and mortality and initiate timely treatment to reduce mortality and improve quality of life. The aim of our study is to find the correlation between echocardiographic Changes and the changes in the level of NT-proBNP by identifying the Minimal Important Change in NT-proBNP levels which have clinical relevance in the diagnosis of HF in Octogenarians in Belgium. Methods: two methods are often used in the identification of the MIC, but because they have limits when used separately, we decided to use the combined method called the visual anchor-based MIC distribution method proposed by Crosby et al. MIC was then calculated from echocardiographic changes (used as anchor) and deteriorated patients ,patients with positive change NT-proBNP scores at T1. The optimal cut-off point considered as the MIC corresponds to the point at which there is the least amount of classification of the sum of sensitivity and specificity. Kaplan Meier and multivariate cox analysis were used to validate the results. Data derived from BELFRAIL study. Results: the MIC in NT-proBNP levels identified was 150pg/ml which correspond to the category 4 of the the minimal amount of misclassification representing the Log- transformed NT-proBNP =1.2. To validate the results, a Kaplan Meier and multivariate cox survival analysis were conducted and they confirmed that a rise of ≥150pg/ml is an indicator of an important change and is an indepedent predictor of mortality. Conclusion: in real practice, if the levels of NT-proBNP go up >150pg/ml from the initial value, the patient should be reevaluated through echocardiography.