Epidemiological and clinical features, therapeutic strategies and outcomes in patients with hyperhaemolysis: A systematic review.

Hyperhaemolysis syndrome (HHS), a severe form of delayed haemolytic transfusion reaction most commonly described in patients with sickle cell disease (SCD), involves destruction of both donor and recipient red blood cells (RBCs). As the epidemiology and underlying pathophysiology have yet to be definitively elucidated, recognition can be challenging. We systematically reviewed PubMed and EMBASE to identify all cases of post-transfusion hyperhaemolysis and characterized the epidemiological, clinical and immunohaematological characteristics and treatments of HHS. We identified 51 patients (33 females and 18 males), including 31 patients with SCD (HbSS, HbSC and HbS/β-thalassaemia). The median haemoglobin nadir (3.9 g/dL) occurred a median of 10 days post-transfusion. 32.6% and 45.7% of patients had a negative indirect anti-globulin test and a negative direct anti-globulin test, respectively. The most common therapies included corticosteroids and intravenous immune globulin. 66.0% of patients received ≥1 supportive transfusion, which was associated with a longer median hospital stay/time to recovery (23 days vs. 15 days; p = 0.015) compared to no supportive transfusion. These findings illustrate that HHS that often results in marked anaemia 10 days post-transfusion is not restricted to patients with haemoglobinopathies, and additional transfused RBCs may be associated with a longer time-to-recovery.