Background: Chronic heart failure represents a major public health challenge. In Denmark, there is an increasing incidence, leading to a growing economic burden and societal strain. The current diagnostic strategy involves referring all patients for echocardiography based on a clinical examination. However, a promising and less costly rule-out biomarker, NT-proBNP, exists and has demonstrated effectiveness in primary care while resulting in cost savings. Several international guidelines recommend the use of NT-proBNP, however, there is inconsistency regarding an appropriate threshold for the general population. Despite these recommendations, NT-proBNP has not been fully implemented in Denmark. Therefore, this Master’s thesis aims to investigate the cost- effectiveness of NT-proBNP compared to the standard of care and different thresholds in a Danish setting. Additionally, to clarify the budgetary consequences of the implementation of NT-proBNP. Method: A cost-utility analysis was performed using a decision tree comparing three strategies; the standard of care, initial screening with NT-proBNP at a threshold of 125 pg/ml, and a threshold of 400 pg/ml from a healthcare perspective over a year. Moreover, deterministic and probabilistic sensitivity analyses were conducted to assess the uncertainties of the base case. Also, a budget-impact analysis over five years was performed including a scenario with a lower price for the NT-proBNP laboratory analysis.Two systematic literature searches were conducted to identify existing evidence on the use of NT- proBNP in primary care and cost analyses, respectively.Results: The strategy with an NT-proBNP threshold of 400 pg/ml was found to be cost-effective compared to the other strategies due to lower costs and greater health benefits, with a robust result to uncertainties. The implementation of NT-proBNP would result in savings of DKK 2-60 million over five years compared to the standard of care, potentially increasing to above DKK 80 million if the costs for NT-proBNP laboratory analysis decrease.Conclusion: In conclusion, the implementation of NT-proBNP in primary care in Denmark is cost- effective. A threshold of 400 pg/ml was deemed cost-effective; however, it might be associated with a higher risk of missing diagnoses due to interpersonal differences, comorbidities, phenotypes, and risk factors.