Impact of chronic transfusion on incidence of pain and acute chest syndrome during the Stroke Prevention Trial (STOP) in sickle-cell anemia

OBJECTIVE

The Stroke Prevention Trial (STOP) demonstrated that chronic transfusion is highly effective in reducing the risk of stroke in children with sickle-cell disease and an abnormal transcranial Doppler ultrasonography examination result. Our objective was to determine whether chronic transfusion therapy reduces the incidence of pain and acute chest syndrome.

METHODS

During STOP, 130 children with sickle-cell anemia or sickle beta(0)-thalassemia and abnormal transcranial Doppler ultrasonography examination result were randomly assigned to chronic transfusion (n = 63) or observation (n = 67). In addition to monitoring for stroke, nonneurologic sickle-cell complications were identified and recorded.

RESULTS

Mean age at STOP study entry was 8.3 +/- 3.3 years, and mean follow-up was 19.6 +/- 6.5 months. Hospitalization rates (based on intent-to-treat analysis) for acute chest syndrome were 4.8 and 15.3 per 100 patient-years (P =.0027) and for pain were 16.2 and 27.6 per 100 patient-years (P =.13) in the chronic transfusion and observed groups, respectively. If analyzed according to treatment actually received, the difference in pain rate becomes significant (9.7 vs 27.1 events per 100 patient-years, P =.014), and transfusion remains protective from acute chest syndrome (2.2 vs 15.7 events per 100 patient-years, P =.0001).

CONCLUSIONS

Compliance with aggressive chronic transfusion reduces the frequency of acute chest syndrome and pain episodes.

A novel multilocus genotyping assay to identify genetic predictors of stroke in sickle cell anaemia

We describe a novel multilocus genotyping assay permitting simultaneous identification of 60 candidate markers for stroke in sickle cell anaemia (SCA). Based on cerebral magnetic resonance imaging (MRI), 69 patients were divided into stroke and control groups. The variant allele, CBS 278thr, showed protection from stroke, whereas the apoE3 allele showed a trend towards association with increased stroke risk. Several other variant alleles [TNFalpha (-308)A, CETP (-628)A, apoCIII (-641)A] showed a trend towards significant associations with stroke risk. These preliminary results on a small group of patients suggest that a multilocus genotyping assay may be valuable in identifying genes that increase the risk of stroke in SCA.

Changing outcome of homozygous alpha-thalassemia: cautious optimism

Only a few long-term survivors of homozygous alpha-thalassemia, a usually fatal condition, have been reported. The authors present a surviving infant with this disorder and discuss the complications, treatments, and implications of this genetic hemoglobinopathy. The child had no antenatal intervention and has been treated with regular transfusions. She has had normal growth and development and is currently 2.5-years-old. A literature review of survivors with Bart hemoglobinopathy reveals an intense perinatal course and a great prevalence of congenital urogenital and limb defects. Advances in antenatal diagnosis, intrauterine intervention, and postnatal treatments have resulted in extended survival of children with congenital defects that until recently were considered invariably fatal. Transfusion and chelation therapy and bone marrow transplantation provide long-term treatment and potential curative options.

Use of hydroxyurea in children ages 2 to 5 years with sickle cell disease

The efficacy and side effects of hydroxyurea in young children with sickle cell disease are unknown. The authors followed-up eight young children (mean age 3.7 years) during therapy with hydroxyurea for an average of 137 weeks. Total and fetal hemoglobin levels rose with hydroxyurea therapy. Hospital admission rates and total hospital days decreased during hydroxyurea therapy. No unexpected toxicity occurred, and growth and development were unaffected. This pilot study suggests that hydroxyurea is safe and effective in young children with sickle cell disease.

Hydroxyurea and sodium phenylbutyrate therapy in thalassemia intermedia

Hydroxyurea (HU) and sodium phenylbutyrate (SPB) have been shown to increase fetal hemoglobin (Hb F) levels in patients with thalassemia intermedia. The reported effects of these agents in increasing total Hb, however, have been inconsistent and there have been no studies on the combination of these medications. We describe the clinical response, as determined by increases in total Hb and decreased transfusion needs, in five patients with thalassemia intermedia treated with HU alone or in combination with SPB. All of the patients responded with increased levels of Hb F, but the responses in total Hb varied. Of the five patients, two had a marked response in total Hb in excess of 3 g/dl, two responded modestly with an increase in total Hb of 1-2 g/dl, and one did not respond. Prolonged responses were achieved with low doses of HU (3-10 mg/kg/day) and higher doses were associated with mild reversible hematologic or hepatic toxicity and no further increases in Hb. Sodium phenylbutyrate was added to treatment with HU in two patients, but failed to produce an increase in total Hb despite increasing Hb F levels. Of the four patients who responded to HU with an increase in total Hb, all reported symptomatic improvement and three have not required further transfusions. We conclude that low-dose HU therapy in patients with thalassemia intermedia may increase total Hb levels sufficiently to eliminate the need for transfusions. We, therefore, recommend a trial of HU for thalassemia intermedia patients in whom chronic transfusion therapy is being contemplated.

Effects of red blood cell transfusion on resting energy expenditure in adolescents with sickle cell anemia

BACKGROUND

Previous studies indicate that resting energy expenditure is elevated in children with sickle cell anemia, possibly caused in part by hemolysis and increased erythropoietic activity. The purpose of the present investigation was to determine whether erythrocyte transfusion normalizes resting energy expenditure in sickle cell anemia.

METHODS

Five adolescents with sickle cell anemia (12-16 years old; 4 boys, 1 girl) were studied before and 1 week after erythrocyte transfusion before elective surgery or at the initial transfusion for growth failure. Resting energy expenditure was measured by indirect calorimetry, and laboratory measures were determined by routine, validated methods. Data comparisons were by nonparametric analysis.

RESULTS

After erythrocyte transfusion, total hemoglobin levels increased (difference (D) = 15 g/l; p < 0.05), whereas hemoglobin S (D = -0.36; p < 0.05) and reticulocyte count (D = -0.12; p < 0.05) decreased. Mean pretransfusion resting energy expenditure was elevated to 124% above predicted levels (p < 0.05) and increased further to 134% above prediction (p < 0.05 vs. pretransfusion levels). Plasma triiodothyronine (T3) levels increased (D = 0.17 nmol/l; p < 0.05), reverse T3 (rT3) levels tended to decline (D = -0.04 nmol/l; p = 0.14), and rT3/T3 decreased (D = -0.03; p < 0.05). Plasma insulin-like growth factor-I (IGF-I) levels were low-normal before transfusion and did not change, despite the change in resting energy expenditure.

CONCLUSIONS

The results confirm that resting energy expenditure is elevated in patients with sickle cell anemia. However, resting energy expenditure further increased after transfusion, despite decreased erythropoietic activity. A posttransfusion decrease in rT3/T3 may contribute to the increased resting energy expenditure. That there was no change in IGF-I implies that the growth hormone-IGF system is not involved in posttransfusion regulation of resting energy expenditure. Therefore, our data are not consistent with the hypothesis that increased resting energy expenditure in sickle cell anemia is directly related to erythropoietic activity. The mechanisms by which resting energy expenditure increases after transfusion in sickle cell anemia require additional investigation.

Clinician assessment for acute chest syndrome in febrile patients with sickle cell disease: is it accurate enough?

STUDY OBJECTIVE

To determine whether the use of empiric chest radiography (CXR) is of significant value in detecting clinically unsuspected acute chest syndrome (ACS) in febrile patients with sickle cell disease (SCD).

METHODS

Patients with SCD presenting to the emergency department and hematology clinic with temperature greater than or equal to 38 degrees C were prospectively evaluated using a physician-completed questionnaire. The questionnaire included inquiries into the patient's physical signs and symptoms and the physician's clinical impression for the presence of ACS. The questionnaire was completed before obtaining CXR results in all patients.

RESULTS

Seventy-three patients with SCD with 96 febrile events were evaluated over a 1-year period. Twenty-four percent (23/96) of the patients had CXR evidence of ACS. On the basis of the questionnaire data, 61% (14/23) of ACS cases were not clinically suspected by the evaluating physician before obtaining CXR. Comparing the patients with and without ACS revealed that, with the exception of splinting (4/23 [17%] versus 0/73 [0%]), no symptom or physical examination finding helped to identify which patients had ACS. Fifty-seven percent of patients with ACS had completely normal findings on physical examination. The presentation of patients with clinically detected versus clinically unsuspected ACS also did not differ significantly. Length of hospitalization, oxygen use, and need for transfusion were the same in both the unsuspected and detected ACS groups. Overall physician sensitivity for predicting ACS was only 39%, and diagnostic accuracy did not improve significantly with increasing levels of pediatric training.

CONCLUSION

ACS is common in patients with SCD who present with fever and was grossly underestimated by evaluating physicians. History and physical examination appear to be of little value in defining which febrile patients require CXR. In view of the mortality and morbidity associated with ACS, empiric CXR should be considered when evaluating a febrile patient with SCD.

The hemoglobin E syndromes

Heterozygotes and homozygotes for HbE (beta 26, GAG-AAG, Glu-Lys) are microcytic, minimally anemic, and asymptomatic. The microcytosis is attributed to the beta thalassemic nature of the beta E gene, whereas the in vitro instability of HbE does not contribute to the phenotype. However, the compound heterozygote state HbE/beta thalassemia results in a variable, and often severe anemia, with the phenotype ranging from transfusion dependence to a complete lack of symptoms. This has been well documented in Thailand, but the basis of the interaction and the cause of the variability remains unexplained. We have studied 50 HbE/beta thalassemics from the UK and 16 from Oakland, CA and assessed the role of HbE instability. Time-course globin chain synthesis experiments have shown that instability is not an important factor in the steady state, but that at 41 degrees C newly synthesized Hb molecules are unstable. We have identified one family in which HbE interacts with pyrimidine 5' nucleotidase deficiency to cause severe anemia with Hb instability. The UK individuals, mostly of Bengali origin, have Hb's from 4.5-11 g/dl. The beta thalassemia mutation, alpha thalassemia and the Xmn 1 G gamma polymorphism do not explain this variability, but the relative and absolute amounts of HbF correlate significantly with total Hb. The Oakland individuals, mostly from Southeast Asia, show similar variation in Hb, which again is largely unexplained.

Membrane phospholipid asymmetry in human thalassemia

Phospholipid asymmetry in the red blood cell (RBC) lipid bilayer is well maintained during the life of the cell, with phosphatidylserine (PS) virtually exclusively located in the inner monolayer. Loss of phospholipid asymmetry, and consequently exposure of PS, is thought to play an important role in red cell pathology. The anemia in the human thalassemias is caused by a combination of ineffective erythropoiesis (intramedullary hemolysis) and a decreased survival of adult RBCs in the peripheral blood. This premature destruction of the thalassemic RBC could in part be due to a loss of phospholipid asymmetry, because cells that expose PS are recognized and removed by macrophages. In addition, PS exposure can play a role in the hypercoagulable state reported to exist in severe beta-thalassemia intermedia. We describe PS exposure in RBCs of 56 comparably anemic patients with different genetic backgrounds of the alpha- or beta-thalassemia phenotype. The use of fluorescently labeled annexin V allowed us to determine loss of phospholipid asymmetry in individual cells. Our data indicate that in a number of thalassemic patients, subpopulations of red cells circulate that expose PS on their outer surface. The number of such cells can vary dramatically from patient to patient, from as low as that found in normal controls (less than 0.2%) up to 20%. Analysis by fluorescent microscopy of beta-thalassemic RBCs indicates that PS on the outer leaflet is distributed either over the entire membrane or localized in areas possibly related to regions rich in membrane-bound alpha-globin chains. We hypothesize that these membrane sites in which iron carrying globin chains accumulate and cause oxidative damage, could be important in the loss of membrane lipid organization. In conclusion, we report the presence of PS-exposing subpopulations of thalassemic RBC that are most likely physiologically important, because they could provide a surface for enhancing hemostasis as recently reported, and because such exposure may mediate the rapid removal of these RBCs from the circulation, thereby contributing to the anemia.

Acute chest syndrome and sickle cell disease

Acute chest syndrome (ACS) is the presence of a new pulmonary infiltrate in combination with fever or respiratory symptoms in a patient with sickle cell disease. ACS is the leading cause of death in sickle cell disease, and many patients suffer from multiple, severe episodes. Age has a striking effect on the clinical course and outcome of ACS, with children having milder disease that often is infectious. Adults often have severe disease, and pulmonary fat embolism is frequently a component of severe ACS. Rapid diagnosis and appropriate therapy including antibiotics for atypical infections, fluids, aerosolized beta agonists, and adequate pain control are necessary to reduce morbidity. Transfusion is indicated in hypoxic patients and can be used to prevent recurrent episodes. As the pathophysiology of ACS is further delineated, new treatment strategies will be investigated.

The natural history of sickle cell disease

Sickle cell disease results in significant morbidity and mortality for those affected with this disease. Despite the fact that every case of sickle cell disease results from the same genetic mutation, there is considerable heterogeneity in the clinical course of the disease. Considerable knowledge has been gained regarding the complications of sickle cell disease including pain episodes, infections, stroke, and lung disease. Clarifying the clinical course of sickle cell disease has enabled us to develop therapies to decrease the morbidity of this disease and, with hope, will direct further investigations into novel treatment interventions.

The mortality of Royal Naval submariners 1960-89

OBJECTIVES

To examine the mortality pattern of submariners in the Royal Navy to assess the long term effects on health of serving in submarines. Any specific cause of death which was increased was considered in advance to be of interest, but attention focused particularly on cancer mortality.

METHOD

A mortality follow up study: 15 138 submariners who had conducted their first submarine training between 1960 and 1979 were followed up through their time in the Navy and into civilian life, up to the end of 1989. The main outcome measures were the numbers of deaths and standardised mortality ratios (SMRs) which indicate whether the mortality from all causes and specific causes, particularly cancers, exceeds that in men in England and Wales.

RESULTS

Mortality in submariners was lower than that for men in England and Wales with an all cause SMR of 86; this was comparable with that found in other studies of armed forces personnel. Cancer mortality was particularly low with an SMR of 69 and there was no particular cancer site which showed an excess. Increased mortality from digestive diseases was found, the excess being attributable to cirrhosis of the liver, which had an SMR of 221 based on 12 deaths, alcohol being a contributory factor in eight. Deaths from accidents and violence were also higher than expected with an SMR of 115, but this was due to high levels of accidents occurring after discharge from the Navy. There was no apparent trend in mortality with time since starting submarine work. Likewise there was no pattern by calendar period, although the excess of cirrhosis of the liver was confined to the period 1970-9.

CONCLUSION

The submariners seemed to be a healthy group with low mortality overall. Working in submarines was not associated with any increased cancer mortality. Excess deaths from cirrhosis of the liver, and from accidents and violence after leaving the Navy, were of some concern but they cannot be attributed directly to the submarine environment.

Pulmonary complications

The management of patients with acute chest syndrome is changing as its etiology and pathophysiology are being defined. Current management should include aggressive evaluation and monitoring, and treatment should be tailored to each patient's clinical course. New therapies show promise in reducing morbidity of acute chest syndrome in the future.