Chronic hyper-hemolysis in sickle cell anemia: Association of vascular complications and mortality with less frequent vasoocclusive pain

Background: Intravascular hemolysis in sickle cell anemia could contribute to complicate associated with nitric oxide deficiency, advancing age, and increased mortality. We have previoulsy reported that intense hemolysis is associated with validated in other populations. Methods: The distribution of serum lactic dehydrogenase (LDH) values was used as a surrogate measure of intravascular hemolysis in a contemporaneous patient group and historical adult population from the Cooperative of Sickle Cell Disease (CSSCD), all with sickle cell anemia. Chronic hyper-hemolysis was defined by the top LDH quartile and was compared to the lowest LDH quartile. Results: Hyper-hemolysis subjects had higher systolic blood pressure, higher prevalence of leg ulcers (OR 327.95% Cl 1.92-5.53, P<0.0001), priapism (OR 2.62, 95% Cl 1.13-6.90, P=0.03) and pulmonary hypertension (OR 4.32, 95% Cl 2.12-8.60, P<0.0001), while osteonecrosis (OR 0.32, 95% Cl 0.19-0.54, P<0.0001) and pain (OR 0.23. 95% Cl 0.09-0.55, P=0.0004) were less prevalent. Hyper-hemolysis was influenced by fetal hemoglobin and α thalassemia, and was a risk factor for early death. Conclusions: Steady state LDH measurements can identify a chronic hyper-hemolysis phenotype which includes less frequent vasooclusive pain and earlier mortality. Clinicians should consider sickle cell specific therapies for these patients, as is done for those with more frequent acute pain. The findings also suggest that an important class of disease modifiers in sickle cell anemia affect the rate of hemolysis.