Table 1.

Definitions of SCD-related events

Painful crises: bone or abdominal pain or hand-foot syndrome lasting for more than 4 hours and attributable to SCD
Stroke: isolated acute neurologic symptoms lasting for more than one day
Acute splenic sequestration: sudden enlargement of spleen associated with a worsening of anemia requiring immediate blood transfusion
Aplastic crisis: progressive worsening anemia with absence of reticulocytes
Acute chest syndrome: chest/thoracic pain with infiltrate on chest x-ray and respiratory distress and significant drop in the hemoglobin level
Malarial attack: > 2000 infected red blood cells/mm3