CRP and hydrops fetalis: Patients with HF and frailty displayed significantly higher levels of BNP (k = 11; SMD: 0.53, 95%CI 0.30-0.76, I<sup>2</sup> = 86%, P < 0.01), NT-proBNP (k = 23; SMD: 0.33, 95%CI 0.25-0.40, I<sup>2</sup> = 72%, P < 0.01), and CRP (k = 8; SMD: 0.30, 95%CI 0.12-0.48, I<sup>2</sup> = 62%, P < 0.01) vs. patients with HF without frailty.