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. These results demonstrate that the model is being driven by the greater cost reductions and QALY benefits of diagnosing other conditions in the non-heart failure population earlier, rather than the cost reductions and QALY benefits of an earlier diagnosis of heart failure. The committee noted that the QALYs accrued for the heart failure population are very similar across all of the strategies (difference of 0.01 QALYs between the 400pg/ml threshold (lowest QALYs for people with heart failure) and referring all patients for echocardiography (highest QALYs for people with heart failure). The committee was reassured to know that the difference was so small. However, acknowledged that this small difference is likely to be due to the low proportion of people with HF-REF in the model, and hence limited QALY gains from early treatment. Although the REFER study seemed the most appropriate study to choose for the base case analysis as it was the most recent UK study, the committee voiced concern about the very small proportion of HF-REF patients in the study population. The committee considered that this may be due to study selection bias, as patients with severe symptoms, who are thought to be of high risk, are often not recruited into these types of clinical studies due to concern that there would be a delay in their treatment. The committee considered that the patients considered to be of high risk are more likely to have HF-REF than HF-PEF. However, the extent of possible selection bias is unknown. 