What is the reason the committee decided to contact study authors seeking additional data at the particular thresholds?
The committee decided to contact study authors seeking additional data at the particular thresholds because their ability to establish the most appropriate test thresholds was limited by the thresholds reported by the included studies. The committee also acknowledged the high sensitivity from one study conducted in 1997, but considered that the heart failure population has changed significantly since this study was conducted with a greater proportion of people with HF-PEF, which on a population level tend to have lower NT-proBNP levels than people with HF-REF. Therefore they were uncertain as to whether these results would represent the diagnostic accuracy for BNP testing in current practice. In contrast, the majority of the high quality NT-proBNP studies were more recent and likely to be applicable to current practice. Furthermore, the Zaphiriou study (high quality study assessing both BNP and NT-proBNP) assessed the recommended industry cut-offs for each test. 