Chronic Heart Failure Diagnosing heart failure There is no mortality or morbidity benefit of treatment for HF-PEF patients. Heart failure for those with a NT-proBNP level < 400pg/ml will be less severe compared to those above the threshold and therefore mortality and hospitalisation rates will be lower than those reported in the literature. The cost and disutility consequences of missing these patients is therefore likely to be lower than for those with higher NT-proBNP levels. An individual s NT-proBNP level does not affect the rate of hospitalisation or mortality for other (non-HF) conditions. In heart failure patients with NT-proBNP levels <400pg/ml (treated or untreated) a hospitalisation causes their NT-proBNP levels to permanently be raised over 400pg/ml due to a worsening in their heart failure. Untreated heart failure patients (both HF-REF and HF-PEF) progress to having NT-proBNP levels >400pg/ml after 6 months if they have not already progressed due to hospitalisation. As HF-PEF patients are considered as untreated, all HF-PEF patients therefore progress to higher severity 6 months after first presentation. Treated low severity HF-REF patients who do not experience a hospitalisation progress to having NT-proBNP levels >400pg/ml 5 years after first presentation. The most common alternative diagnoses if a patient does not have heart failure are COPD, myocardial ischaemia, and obesity. The committee considered that the percentage of patients with these conditions would be 35% and 15%, and 50%, respectively. Patients do not have multiple-morbidities. Model inputs were based on clinical evidence identified in the systematic review undertaken for the guideline, supplemented by additional data sources as required. These are described in full in the technical report in Appendix O. All model inputs and assumptions were validated by the guideline committee. Sensitivity analyses were also undertaken in areas of uncertainty to see how robust the model results are. 