Abstract
<b><i>Introduction:</i></b> Exogenous haptoglobin administration may enhance plasma-free hemoglobin (pfHb) clearance during hemolysis and reduce its end-organ damage: we systematically reviewed and summarized available evidence on the use of haptoglobin as a treatment for hemolysis of any cause. <b><i>Methods:</i></b> We included studies describing haptoglobin administration as treatment or prevention of hemolysis-related complications. Only studies with a control group reporting at least one of the outcomes of interest were included in the quantitative synthesis. Primary outcome was the change in pfHb concentration 1 h after haptoglobin infusion. <b><i>Results:</i></b> Among 573 articles, 13 studies were included in the review (677 patients, 52.8% received haptoglobin). Median initial haptoglobin intravenous bolus was 4,000 (2,000, 4,000) IU. Haptoglobin was associated with lower pfHb 1 h (SMD −11.28; 95% CI: −15.80 to −6.75; <i>p</i> < 0.001) and 24 h (SMD −2.65; 95% CI: −4.73 to −0.57; <i>p</i> = 0.001) after infusion. There was no difference in all-cause mortality between haptoglobin-treated patients and control group (OR 1.41; 95% CI: 0.49–4.95; <i>p</i> = 0.520). Haptoglobin was associated with a lower incidence of acute kidney injury (OR 0.64; 95% CI: 0.44–0.93; <i>p</i> = 0.020). No adverse events or side effects associated with haptoglobin use were reported. <b><i>Conclusions:</i></b> Haptoglobin administration has been used in patients with hemolysis from any cause to treat or prevent hemolysis-associated adverse events. Haptoglobin may reduce levels of pfHb and preserve kidney function without increase in adverse events.