One study in this review, by Alqaisi et al[45], compared the accuracy of different algorithms for identifying HF, some of which included BNP levels, and the highest-sensitivity algorithm in that study was ≥2 outpatient encounters for HF, or ≥1 hospitalizations for HF, or a BNP level of ≥200 pg/ml. This evidence concerns the gene NPPB and hydrops fetalis.