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Assessing clinical severity in children with sickle cell disease. Preliminary results from a cooperative study
1Department of Pediatrics, George Washington University School of Medicine, Washington, DC.
Insights
Identifying early childhood indicators for sickle cell disease severity is crucial for timely bone marrow transplants. This study aims to find predictive factors for better patient selection and outcomes.
Area of Science:
- Hematology
- Pediatric Medicine
- Genetics
Background:
- Sickle cell disease (SCD) is curable with bone marrow transplantation (BMT), but suitable candidate identification is challenging.
- The disease has a variable clinical course, necessitating intervention before chronic organ damage occurs.
- A clinical severity index is needed to identify high-risk SCD patients for BMT.
Purpose of the Study:
- To identify early childhood features (< 2 years) predictive of later morbidity or mortality in SCD.
- To establish objective criteria for selecting pediatric candidates for bone marrow transplantation.
- To develop a clinical severity index for improved SCD patient management.
Main Methods:
- Utilized the Cooperative Study of Sickle Cell Disease database with 1,944 pediatric patients (< 12 years).
- Performed univariate analysis to identify features associated with cerebrovascular accidents and mortality.
- Defined a new endpoint: the distribution of acute events (pain, acute chest syndrome) and age-specific expected event rates.
Main Results:
- Low hematocrit was a significant predictor of death in the pediatric cohort.
- Factors like hematocrit, rate of change of pocked red cell count, and PF40 were associated with cerebrovascular accidents.
- The study established a method to assess acute event rates for further analysis.
Conclusions:
- The relationship between SCD aspects and high positive deviance from expected event rates will be assessed.
- A cohort of 519 infants (< 7 months) followed beyond age two will be used for this assessment.
- This research aims to refine criteria for BMT in pediatric SCD patients.
Purpose:
Although it is clear that sickle cell disease is curable with bone marrow transplantation, there are few objective criteria that are helpful in the identification of suitable candidates for this aggressive and potentially life-threatening procedure. This disease is characterized by a highly variable clinical course, and there is a need to intervene with marrow transplant before the onset of disease-mediated chronic organ damage. These factors high-light the need for a clinical severity index that can prospectively identify patients who are at high risk for a turbulent clinical course and a poor prognosis.
Patients And Methods:
We used the Cooperative Study of Sickle Cell Disease data base to identify features of the disease in early childhood (i.e., < 2 years of age) that are associated either with significant morbidity later in childhood or early mortality. Our study population includes the 1,944 children who entered the study before 12 years of age. Univariate analysis showed that factors associated with the occurrence of cerebrovascular accident (51 patients) include hematocrit, rate of change of pocked red cell count, and polymer fraction at 40% oxygen saturation (PF40). Only low hematocrit was predictive of death in this pediatric cohort (45 disease-related deaths).
Results:
Our ability to identify other potential factors that correlate with these outcome measures is limited by their small numbers. Hence, it was necessary to designate a different endpoint whose relationship with various clinical and laboratory parameters could be assessed. To accomplish this, a distribution of acute events, which were defined as any episode of pain or acute chest syndrome, was calculated. Also, the age-specific "expected" event rate, defined as the mean number of events per patient-year of observation, was determined.
Conclusions:
The relationship between various aspects of sickle cell disease and high positive deviance from the expected event rate will be assessed in a cohort of 519 children who entered the study prior to 7 months of age and were followed beyond their second birthday.