Stability over time of hematological variables in 197 children with sickle cell anemia

Association of Pulsatility Index in the Middle Cerebral Artery with Intelligence Quotient in Children with Sickle Cell Disease

The aim of this study was to explore whether intellectual performance in children with Sickle Cell Disease and with low risk of stroke as determined with conventional transcranial Doppler ultrasonography (TCD) criteria was associated with hemodynamic parameters in imaging TCD, when controlling for hematological and socio-economical variables and presence of silent infarcts. We performed neuropsychological testing with Kaufman Brief Intelligence Test (K-BIT-IQ) and imaging TCD examinations to measure blood flow velocities and pulsatility indexes (PI) in the middle cerebral arteries (MCA) In 46 children with homozygous HbSS (mean age 108±34 months, range limits: 47–166 months; 24 females), without a history of stroke or transient ischemic attack, with no stenosis on magnetic resonance angiography and with velocities below 170 cm/s in screening conventional TCD. Mean K-BIT IQ Composite and Vocabulary scores (91±13 and 86±14 respectively) were significantly below the average scores of 100 for the age-matched population (one sample t-test=5.21, p<0.001). Using univariate and multivariate regression models, we found that lower PI in the right MCA was associated with lower K-BIT-IQ Composite and Vocabulary scores. Furthermore, we found that interhemispheric differences in PIs were even more strongly associated with neuropsychological performance, whereas flow velocities were not associated with the K-BIT-IQ score. Using a model of chronic anemia, we found that cognitive functioning was associated with cerebral hemodynamics.

Differences between males and females in adult sickle cell pain crisis in eastern Saudi Arabia

BACKGROUND

Sickle cell disease (SCD) is highly prevalent in the Al-Hasa area of eastern Saudi Arabia. We analyzed our patient data to try and find an explanation for the unexpected observation that more males than females with SCD were transferred to the hospital after a stay in the stabilization unit.

PATIENTS AND METHODS

We compared differences between males and females in demographics, pattern of response to treatment for pain, and discharge records for SCD patients admitted to the stabilization unit during the years 2000 to 2002.

RESULTS

Approximately 20% of patients were transferred to the hospital and the remainder were discharged home. Males were admitted more often to the stabilization unit for pain control. Males were also over-represented among those whose pain persisted for over 47 hours and needed hospitalization. Female patients were distributed more evenly over the age groups; there were fewer males in the older age groups.

CONCLUSION

These preliminary observations point to the need for further studies into gender differences in pain crisis in patients with SCD.

Brain injury in children with sickle cell disease: Prevalence and etiology

Our objective was to evaluate the relationship between brain injury by magnetic resonance imaging (MRI) and vasculopathy by magnetic resonance angiography (MRA) in children with hemoglobin SS, the most serious form of sickle cell disease. We reviewed imaging for all 146 SS patients imaged at St. Jude Children's Research Hospital since 1993. Standard MRI criteria were used to identify cystic infarction, leukoencephalopathy, encephalomalacia, or atrophy. Standard MRA criteria were used to identify arterial tortuousity (limited vasculopathy), and stenosis or occlusion (extensive vasculopathy). At an average age of 10 years, the estimated prevalence of infarction, ischemic damage, or atrophy in SS patients was 46%, and of vasculopathy was 64%. Only 28% of patients were normal by both modalities, and patients abnormal by MRA often were abnormal by MRI (p < 0.00001). Patients with cystic infarction had limited vasculopathy, whereas patients with encephalomalacia had stenosis or occlusion (p < 0.0001). Large arteries were affected in 31% of brain injury patients, whereas small arteries are inferred to be abnormal in up to 69% of patients with brain injury. The degree of vasculopathy is closely related to the degree of brain injury, implying that vasculopathy is prodromal to most forms of brain injury in hemoglobin SS.

Mortality in sickle cell disease. Life expectancy and risk factors for early death

BACKGROUND

Information on life expectancy and risk factors for early death among patients with sickle cell disease (sickle cell anemia, sickle cell-hemoglobin C disease, and the sickle cell-beta-thalassemias) is needed to counsel patients, target therapy, and design clinical trials.

METHODS

We followed 3764 patients who ranged from birth to 66 years of age at enrollment to determine the life expectancy and calculate the median age at death. In addition, we investigated the circumstances of death for all 209 adult patients who died during the study, and used proportional-hazards regression analysis to identify risk factors for early death among 964 adults with sickle cell anemia who were followed for at least two years.

RESULTS

Among children and adults with sickle cell anemia (homozygous for sickle hemoglobin), the median age at death was 42 years for males and 48 years for females. Among those with sickle cell-hemoglobin C disease, the median age at death was 60 years for males and 68 years for females. Among adults with sickle cell disease, 18 percent of the deaths occurred in patients with overt organ failure, predominantly renal. Thirty-three percent were clinically free of organ failure but died during an acute sickle crisis (78 percent had pain, the chest syndrome, or both; 22 percent had stroke). Modeling revealed that in patients with sickle cell anemia, the acute chest syndrome, renal failure, seizures, a base-line white-cell count above 15,000 cells per cubic millimeter, and a low level of fetal hemoglobin were associated with an increased risk of early death.

CONCLUSIONS

Fifty percent of patients with sickle cell anemia survived beyond the fifth decade. A large proportion of those who died had no overt chronic organ failure but died during an acute episode of pain, chest syndrome, or stroke. Early mortality was highest among patients whose disease was symptomatic. A high level of fetal hemoglobin predicted improved survival and is probably a reliable childhood forecaster of adult life expectancy.

Effect of polymerization tendency on haematological, rheological and clinical parameters in sickle cell anaemia

The polymerization tendency of sickle haemoglobin was estimated as a function of oxygen saturation in 30 patients with homozygous sickle cell anaemia. The deformability of their erythrocytes was also measured, by initial-flow-rate filtration at 37 degrees C through pores of 5 microns diameter, and clinical severity was assessed using a visual analogue scale. By means of partial correlation analysis, it was found that correlations between haematological, rheological, and clinical parameters in sickle cell anaemia could be explained on the basis of an association of each variable with polymerization tendency. Patients with the greatest tendency to form polymer had the least deformable erythrocytes and perceived their disease to be more severe as judged by the visual analogue scale. Polymer formation also appeared to be a determinant of the number of dense cells which, in turn, determine haemolytic rate and erythrocyte deformability.

The relationship between fetal hemoglobin and disease severity in children with sickle cell anemia

A study was conducted in a sample of 140 children with sickle cell anemia to evaluate the relationship between hematological variables (%HbF, %HbA2, %Hb, and mean cell volume) and disease severity. A patient's severity status was determined by whether he/she was hospitalized, had a transfusion, and/or had a pain crisis at 2 evaluation periods; the first was based on a patient's history taken at the initial assessment visit to the Wayne State Comprehensive Sickle Cell Center, and the second was based on a 1-3 year follow-up at the center. Fetal hemoglobin was a strong predictor of a patient's hospitalization and transfusion status. A decrease in %HbF of 4.76% (one SD of %HbF) was associated with a 3.58 fold (95% confidence interval, 1.18-7.28) greater odds of being hospitalized both prior to initial assessment and on follow-up, compared to not being hospitalized at either evaluation. Similarly, a decrease in %HbF of 4.76% was associated with a 5.56 fold (95% confidence interval, 1.67-18.96) greater odds of having a transfusion both prior to initial assessment and on follow-up compared to not having a transfusion at either evaluation. Patients who were both hospitalized and transfused at initial assessment and on follow-up (n = 12) had a mean %HbF of 7.59%, while patients who were not hospitalized or transfused at either evaluation (n = 19) had a mean %HbF of 13.61%. Fetal hemoglobin was not a significant predictor of pain crises in this sample of patients. None of the other hematological variables were significant predictors of disease severity in this study. The strong relationship between %HbF and disease severity identified in this study suggests that a single %HbF measurement may be useful in predicting important aspects of the clinical course of children with sickle cell anemia.

The effect of Hb F and alpha-thalassemia on the red cell indices in sickle cell anemia

This study examines the effect of different levels of fetal hemoglobin (Hb F) and the presence or absence of genes for alpha-thalassemia on the red cell indices and degree of anemia among 102 patients with homozygous sickle cell disease (S/S) between the ages of 15 and 62 years. Patients were divided into those with an average Hb F of less than 10 gm/L ("low" Hb F group) and those with greater than 10 gm/L ("high" Hb F group). alpha-Thalassemia was assessed by restriction enzyme analysis of DNA by the Southern blotting technique. Homozygosity for the beta(s) gene was confirmed by restriction enzyme analysis of DNA using the enzyme Mst II. There were 51 patients with four alpha-globin genes, 28 of whom had "high" and 23 "low" Hb F levels. Fifty-one patients had alpha-thalassemia, 38 of whom were heterozygous and 13 homozygous for the 3.7 kb alpha-thalassemia deletion. Nine had "high" and 31 had "low" Hb F. Irrespective of alpha-globin genotype, patients in the high Hb F group had a higher mean Hb, Hct, MCV, and MCH than those in the low HB F group. In patients without alpha-thalassemia Hb F was positively correlated with MCV and MCH (p less than 0.001), patients with high Hb F levels having macrocytosis confirmed by microhematocrit studies. Patients with alpha-thalassemia had a lower MCHC than patients with four alpha-globin genes and this was not significantly affected by the level of Hb F. The combination of alpha-thalassemia and high levels of Hb F appears to result in a distinctive S/S phenotype that is similar to the type of S/S disease described in Southern India.