Chronic Heart Failure Diagnosing heart failure 5.1.5.3.3 Limitations and interpretation This analysis suggests that 400pg/ml is the most cost effective threshold for referring patients presenting to primary care with signs and symptoms of heart failure. Many uncertainties in the model structure, and assumptions were explored in sensitivity analyses. The primary limitation of this model is that the diagnostic accuracy data was taken from one diagnostic accuracy study. This was due to the significant inconsistency in the results when a meta- analysis of three studies was undertaken. The committee discussed the diagnostic accuracy studies chosen for the meta-analysis at length to agree on chosing one of the studies for the base case analysis. The committee were aware of the limitations of the diagnostic accuracy study by Taylor et al. 2016 chosen for the base case analysis. Particularly, the committee were concerned about the low proportion of HF-REF in the study, as they would have expected the proportion of HF-REF patients presenting to primary care to be higher. The diagnostic accuracy study by Verdu et al. 2012 was not considered to be appropriate for the base case analysis as it was a Spanish study and not considered to be representative of current UK practice, and therefore generalisable to a UK population. The committee discussed that Zaphiriou was a UK study, however was conducted over ten years ago and again is unlikely to represent the current UK population presenting to primary care. Additionally, the criteria for diagnosing HF-PEF patients on echocardiography were not specifically defined as they are today. The study by Taylor et al. 2016 were recruited from 28 practices across central England between 2011 and 2013. Therefore, this population was considered by the committee to be the most representative of current the population presenting to primary care in current UK practice. 