Sickle cell disease (SCD) is an inherited haemoglobinopathy disorder caused by mutations in HBB gene with amino-acid substitution on β globin chain. The consequence is synthesis of altered haemoglobin S (HbS) which polymerises in red blood cell (RBC) at deoxygenated state. SCD is associated with chronic haemolytic anaemia, vaso-occlusive crisis (VOC) leading to frequent hospitalisation.

The aim of the study was to to investigate whether a combination of routine laboratory biomarkers of haemolysis could be used to predict VOC development in confirmed SCD patients.

Inclusion Criteria:

• Sickle cell disease

Exclusion Criteria:

• <18 years
• pregnancy
• Patient under protective guardianship or curatorship

All patients in the study were diagnosed and treated for SCD at Rouen University Hospital. Patients were included during annual visit in our tertiary centre. Patients with VOC were included less than 24hours after admission to emergency department. All patients treated with hydroxyurea have been treated for at least three years. All patients received a systematic annual visit to determine VOC development in the year. Patients were analyzed in four subgroups based on genotype and clinical status:

• homozygous SCD (S/S) or β0 thalassemia (S/β0) at steady state;
• homozygous SCD with α3.7 thalassemia (S/Sα3.7) at steady state;
• heterozygous SCD with C haemoglobin (S/C) or β+ thalassemia (S/β+)at steady state;
• patients hospitalized for VOC with any genotype.