Due to the inconsistency in the pooled results and the very low quality of this data as discussed above, the committee did not consider it appropriate to use the pooled results of these thresholds for the base-case analysis. Therefore the committee decided to choose one diagnostic accuracy study for the base case analysis, and use the other two diagnostic studies to undertake scenario analyses adjusting the population characteristics as appropriate. The committee chose to use the diagnostic accuracy data from the REFER study for the base case analysis; however the accuracy of this data was determined from a reference standard that did not include the level of NT- proBNP in part of the criteria for diagnosing heart failure therefore mitigating the effects of incorporation bias. In contrast to the study identified above, this analysis also incorporated the cost and QALY impact of misdiagnosis for a non-heart failure population. For more information on the model methods and data inputs please see Appendix O. This original analysis found that an NT-proBNP threshold of 400pg/ml is the most cost effective strategy at a threshold of 20,000 per QALY gained (ICER: 5,496 compared to echo all) with a probability of 77% of being the most cost effective at the 20,000 threshold. This result was robust to multiple sensitivity analyses varying key input parameters and structural assumptions. This analysis was assessed as directly applicable with potentially serious Chronic Heart Failure Diagnosing heart failure NICE 2018. All rights reserved. Subject to Notice of rights. ISBN: 978-1-4731-3093-7 limitations. The committee discussed the breakdown of costs and QALYs across the strategies. Contrary to the committees previous statement that sensitivity is the most critical outcome, the model suggests that the specificity of the test is most critical with regards to cost effectiveness. 