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George R Buchanan

Publications and source records attributed to George R Buchanan.

At least 19 recordsLinked to original sources
PubMed2006

Incidence and clinical relevance of abnormal complete blood counts in long-term survivors of childhood cancer.

BACKGROUND: The purpose of the study was to determine the incidence and clinical significance of abnormal complete blood counts (CBCs) obtained during follow-up of childhood cancer survivors. METHODS: A retrospective cohort study was conducted on 193 survivors, diagnosed between 1970-1986, who were followed in our center's After Cancer Experience Program and are participants in the Childhood Cancer Survivor Study. Of these patients, 49% were female and 25% were racial/ethnic minorities. The primary outcome was determination of the cumulative percentage of patients having an abnormal CBC by 2 or 3 standard deviations (SDs). Four components of the CBC were examined and employed to define an abnormal CBC: low white blood cell count (WBC), high mean corpuscular volume (MCV), low platelet count, and low hemoglobin concentration. Association of treatment exposures to abnormal values was assessed with a multilevel logistic model. RESULTS: There were 1297 patient visits during 1401 person-years of follow-up. The mean number of visits per survivor was 6.7 (SD 4.2). The cumulative percentage of subjects with at least one abnormal CBC was 70%. The cumulative percent of subjects with a value abnormal by 2 SD was WBC = 23%, MCV = 37%, platelets = 9%, hemoglobin = 49%. For values abnormal by 3 SD, the frequencies were WBC = 3%, MCV = 20%, platelets = 1%, hemoglobin = 27%. None of the patients developed myelodysplastic syndrome or a secondary leukemia during the follow-up period. Exposure to epipodophyllotoxins was associated with an increased risk of having abnormally high MCV values. CONCLUSIONS: Mildly abnormal CBC values are common in survivors of childhood cancer. Abnormal values are often of questionable significance but seem to persist over time. Epipodophyllotoxin therapy was found to be associated with increased frequency of high MCV levels.

Adolescent↗
PubMed2006

Post-thrombotic syndrome is uncommon in childhood cancer survivors.

Deep vein thrombosis occurs in up to 50% of children with tunneled central venous catheters (CVCs). CVC-related deep vein thrombosis involving the upper extremity is usually asymptomatic but can result in post-thrombotic syndrome (swelling, pain, skin changes, and functional impairment). In a cohort of childhood cancer survivors evaluated clinically a mean of 7.5 +/- 2.8 years after completion of therapy who previously had CVCs in place for a median 15.5 months, none of 50 patients (95% CI = 0% to 6%) had these features diagnostic of post-thrombotic syndrome. Five patients had arm circumference 3% to 5% greater ipsilateral to the prior CVC.

Adolescent↗
PubMed2005

Prospective phase 1/2 study of rituximab in childhood and adolescent chronic immune thrombocytopenic purpura.

We assessed safety and efficacy of rituximab in a prospective study of 36 patients, age 2.6 to 18.3 years, with severe chronic immune thrombocytopenic purpura (ITP). The primary outcome of sustained platelets above 50 x 10(9)/L (50,000/mm3) during 4 consecutive weeks, starting in weeks 9 to 12, was achieved by 11 of 36 patients (31%, confidence interval [CI], 16% to 48%). Median response time was 1 week (range, 1 to 7 weeks). Attainment of the primary outcome was not associated with age, prior pharmacologic responses, prior splenectomy, ITP duration, screening platelet count, refractoriness, or IgM reduction. First-dose, infusion-related toxicity was common (47%) despite premedication. Significant drug-related toxicities included third-dose hypotension (n = 1) and serum sickness (n = 2). Peripheral B cells were depleted in all subjects. IgM decreased 3.4% per week, but IgG did not significantly decrease. Rituximab was well tolerated, with manageable infusion-related side effects, but 6% of subjects developed serum sickness. Rituximab is beneficial for some pediatric patients with severe, chronic ITP.

Adolescent↗
PubMed2005

Minor elective surgical procedures using general anesthesia in children with sickle cell anemia without pre-operative blood transfusion.

BACKGROUND: Pre-operative red blood cell (RBC) transfusions are often recommended for patients with sickle cell disease (SCD) who require elective surgery under general anesthesia. However, definitive randomized studies demonstrating the benefit of transfusions in this setting have not been conducted. In particular, the merits of transfusion prior to minor or low-risk surgical procedures in children with SCD have not been demonstrated. PROCEDURE: We hypothesized that children with sickle cell anemia (Hb SS) who have minor elective surgical procedures develop few complications even without pre-operative transfusion. We accessed our Comprehensive Sickle Cell Program's Database to identify all such procedures performed during a 13-year period. Medical records were reviewed to characterize the surgical procedure, the use of transfusions, and perioperative complications. RESULTS: Twenty-eight children with Hb SS had a total of 38 minor surgical procedures. No perioperative transfusions were given in 34 of the cases (85%). Five of these 34 surgeries (15%) were associated with minor post-operative complications (fever or transient pain). No post-operative acute chest syndrome was encountered. CONCLUSIONS: Minor or low-risk elective surgical procedures in children with Hb SS may not routinely require pre-operative transfusion. A randomized clinical trial to compare transfusion with no transfusion for minor surgical procedures is needed.

Adolescent↗
PubMed2004

Prophylactic granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor decrease febrile neutropenia after chemotherapy in children with cancer: a meta-analysis of randomized controlled trials.

PURPOSE: To determine whether prophylactic hematopoietic colony-stimulating factors (CSFs) used in children with cancer reduce the rate of febrile neutropenia, hospitalization duration, documented infection rate, parenteral antibiotic duration, amphotericin B use, or infection-related mortality. METHODS: We included studies in this meta-analysis if their populations consisted of children, if there was randomization between CSFs and placebo or no therapy, if CSFs were administered prophylactically (before neutropenia or febrile neutropenia), and if chemotherapy treatments preceding CSFs and placebo or no therapy were identical. From 971 reviewed study articles, 16 were included. RESULTS: The mean rate of febrile neutropenia in the control arms was 57% (range, 39% to 100%). Using a random effects model, CSFs were associated with a reduction in febrile neutropenia, with a rate ratio of 0.80 (95% CI, 0.67 to 0.95; P =.01), and a decrease in hospitalization length, with a weighted mean difference of -1.9 days (95% CI, -2.7 to -1.1 days; P <.00001). CSF use was also associated with reduction in documented infections (rate ratio, 0.78; 95% CI, 0.62 to 0.97; P =.02) and reduction in amphotericin B use (rate ratio, 0.50; 95% CI, 0.28 to 0.87; P =.02). There was no difference in duration of parenteral antibiotic therapy (weighted mean difference, -4.3; 95% CI, -10.6 to 2.0 days; P =.2) or infection-related mortality (rate ratio, 1.02; 95% CI, 0.34 to 3.06; P =.97). CONCLUSION: CSFs were associated with a 20% reduction in febrile neutropenia and shorter duration of hospitalization; however, CSFs did not reduce infection-related mortality.

Adolescent↗
PubMed2004

Survival of children with sickle cell disease.

Contemporary survival data are not available for children with sickle cell disease (SCD). The few previous childhood SCD cohort studies do not reflect the benefits of modern therapy. We defined an inception cohort of newborns with sickle cell anemia (SS), sickle-beta degrees -thalassemia (S beta degrees ), sickle-hemoglobin C disease (SC), or sickle-beta(+)-thalassemia (Sbeta(+)) who were identified by newborn screening and followed for up to 18 years. The incidence of death and stroke were calculated. Overall survival, SCD-related survival (considering only SCD-related deaths), and strokefree survival were determined. The 711 subjects provided 5648 patient-years of observation. Twenty-five subjects died; mean age at death was 5.6 years. Five patients died from infection. Thirty had at least one stroke. Among SS and Sbeta degrees subjects (n = 448), the overall rates of death and stroke were 0.59 and 0.85/100 patient-years. Survival analysis of SS and Sbeta degrees subjects predicted the cumulative overall, SCD-related, and stroke-free survival to be 85.6%, 93.6%, and 88.5% by 18 years of age. No SCD-related deaths or strokes occurred in SC or Sbeta(+) subjects (n = 263). Childhood mortality from SCD is decreasing, the mean age at death is increasing, and a smaller proportion of deaths are from infection.

Adolescent↗
PubMed2004

The child with immune thrombocytopenic purpura: is pharmacotherapy or watchful waiting the best initial management? A panel discussion from the 2002 meeting of the American Society of Pediatric Hematology/Oncology.

The initial management of immune thrombocytopenic purpura is a topic of debate among pediatric hematologists. The decision whether to start a patient on pharmacotherapy or to employ an approach of watchful waiting and patient education is problematic for this group of physicians. A wide variety of research studies and review articles have been published on either side of this debate. Here, the proceedings from a panel discussion, held at the 2002 American Society of Pediatric Hematology/Oncology meeting, are presented. The panel, composed of experts on both sides of the debate, presented the rationale, benefits, and risks of both pharmacotherapy and the watchful waiting strategy.

Adolescent↗
PubMed2004

Sickle cell disease.

Much progress has been made during the past several decades in gaining understanding about the natural history of sickle cell disease and management approaches aimed at treating or even preventing certain disease complications. The characterization of the human genome now offers the opportunity to understand relationships regarding how gene polymorphisms as well as how environmental factors affect the sickle cell disease phenotype, i.e., the individual patient's overall clinical severity as well as their specific organ function. This chapter explores some of these recent advances in knowledge. In Section I, Dr. Michael DeBaun characterizes the problem of silent stroke in sickle cell disease, comparing and contrasting its clinical and neuroimaging features with overt stroke. Combined, these events affect virtually 40% of children with sickle cell anemia. New understanding of risk factors, associated clinical findings, and imaging technologies are impacting substantially on treatment options. The appreciable cognitive dysfunction and other sequelae of silent infarct demand more effective treatments and ultimate prevention. In Section II, Dr. Charles Quinn addresses the conundrum of why some patients with sickle cell disease do well whereas others fare poorly. Some risk factors have been known for years, based upon careful study of hundreds of patients by the Cooperative Study for Sickle Cell Disease and investigators studying the Jamaican newborn cohort. Other prognostic measures have only recently been defined. Dr. Quinn devotes special attention to stroke and chest syndrome as organ-related complications but also describes attempts to measure overall disease severity and to predict survival. Recently, investigators have attempted to predict factors responsible for early mortality in children and following onset of pulmonary hypertension in adults. In Section III, Dr. Martin Steinberg reviews pharmacologic approaches to sickle cell disease and the rationale for their use. In addition to the inhibition of hemoglobin S polymerization, newer targets have been defined during the past one to two decades. These include the erythrocyte membrane, changes in the red cell intracellular content (especially loss of water), endothelial injury, and free radical production. Hydroxyurea treatment attracted the greatest interest, but many uncertainties remain about its long-term benefits and toxicities. Newer "anti-sickling" agents such as decitabine and short-chain fatty acids also receive attention. Prevention of red cell dehydration, "anti-endothelial" therapy, and marshalling the potentially beneficial effects of nitric oxide are other new and exciting approaches.

Anemia, Sickle Cell↗
PubMed2003

Severe chronic idiopathic thrombocytopenic purpura during childhood: definition, management, and prognosis.

Chronic idiopathic thrombocytopenic purpura (ITP) can be categorized as mild, moderately severe, or severe. Severe chronic ITP during childhood is a rare disorder characterized by clinically significant mucocutaneous hemorrhage, usually in the setting of marked thrombocytopenia. It can cause substantial morbidity and rarely mortality. Many patients improve with time or even fully recover, but for those whose quality of life is negatively influenced by hemorrhage or side effects of conventional therapy (corticosteroids, intravenous immunoglobulin G, or anti-D), splenectomy is recommended. If splenectomy is unsuccessful or not feasible, other drug treatments are available, but few efficacy data exist, and the toxicity and cost of these treatments can be appreciable. Their use is best avoided outside of clinical trials conducted in specialty centers or in multi-institutional networks.

Adrenal Cortex Hormones↗
PubMed2003

DNA diagnosis confirms hemoglobin deletion in newborn screen follow-up.

Molecular genetic confirmatory testing with polymerase chain reaction amplification is integral to neonatal hemoglobinopathy screening programs. In this study, we demonstrate applicability of polymerase chain reaction-based testing for the common deletions in blacks responsible for hereditary persistence of fetal hemoglobin. This approach will provide rapid diagnostic clarification in newborn screening follow-up.

Alleles↗
PubMed2003

Invasive pneumococcal infections in children with sickle cell disease in the era of penicillin prophylaxis, antibiotic resistance, and 23-valent pneumococcal polysaccharide vaccination.

Rates and severity of pneumococcal infections in children with sickle cell disease were examined before licensure of pneumococcal-conjugated vaccine (PVC). Rates of peak invasive infection rates in 1-year-old children with hemoglobin SS and mortality in those 0 to 10 years of age were 36.5 to 63.4 and 1.4 to 2.8 per 1000 person-years, respectively (>10 and 100 times as frequent as in the general population). Overall, 71% of serotyped isolates (n=80) were PVC serotypes and 71% of nonvaccine serotype strains were penicillin-sensitive. Clinical presentation in children with hemoglobin SS (n=71; more with hypotension) and hemoglobin SC (n=18; more with acute chest syndrome, otitis media) differed. Penicillin nonsusceptibility (38% of isolates) varied between geographic study sites. Penicillin prophylaxis appeared less effective against intermediate and resistant strains. Of all infected children, meningitis developed in 20% and 15% died (hemoglobin SS, n=15 and 11; hemoglobin SC, n=1 each). Factors associated with death included age >4 years (58%), serotype 19F, and not being followed by a hematologist (42% each). The pneumococcal-polysaccharide vaccine was 80.4% effective within 3 years after vaccination (95% CI, 39.7, 93.6). Children with sickle cell disease of all ages may benefit from PVC boosted with polysaccharide vaccination.

Anemia, Sickle Cell↗
PubMed2003

A prospective comparative study of 2540 infants and children with newly diagnosed idiopathic thrombocytopenic purpura (ITP) from the Intercontinental Childhood ITP Study Group.

OBJECTIVE: To analyze prospectively the impact of age at diagnosis in childhood idiopathic thrombocytopenic purpura (ITP). STUDY DESIGN: International registry from June 1997 to May 2001, with analysis of data from baseline and 6-month-follow-up questionnaires. RESULTS: Data from 2540 patients were analyzed, including 203 infants (7.6%), 1860 children > or =1 to <10 years of age (69.1%), and 477 children and adolescents between > or =10 and <16 years of age (17.7%). The mean platelet count at diagnosis was similar in all three groups, as was the percentage of patients with initial platelet count <20x10(9)/L. The male/female ratio was highest in infants and decreased with age (P=.009). Immunoglobulin therapy was used more often in infants and corticosteroids in patients > or =10 years of age. Follow-up information at 6 months was available for 1742 children (68.6%). Chronic ITP was seen less frequently in infants (23.1%) than in children >10 years of age (47.3%, P<.0001). Intracranial hemorrhage occurred in 3 of 1742 children during the first 6 months after the diagnosis of ITP. CONCLUSIONS: Pediatric patients with ITP from infancy to adolescence exhibit heterogeneity in clinical, demographic, and treatment factors.

Adolescent↗
PubMed2003

Self-reported initial management of childhood idiopathic thrombocytopenic purpura: results of a survey of members of the American Society of Pediatric Hematology/Oncology, 2001.

The purpose of this study was to update physicians' self-reported initial management practices for childhood idiopathic thrombocytopenic purpura (ITP) from an initial survey in 1997. A questionnaire was sent by e-mail in October 2001 to 753 members of the American Society of Pediatric Hematology/Oncology (ASPH/O). The questionnaire had 14 questions, based on the clinical presentation of a 5-year-old boy with ITP, a platelet count of 7,000/microL, scattered petechiae, and no mucous membrane bleeding. Two hundred eighteen (29%) surveys were returned. In response to questions regarding initial treatment, 33% of physicians said they would always administer drug therapy, 38% usually, 15% sometimes, and 14% rarely/never. When asked which agent would be used if drug treatment were prescribed, 45% reported anti-D, 33% IVIG, 20% prednisone, and 2% other regimens. Only 34% of physicians would always or usually hospitalize such a patient. Hospitalization was more likely if a physician responded that he or she would always or usually use drug therapy. Physicians who saw more ITP patients were more likely to self-report sometimes or rarely/never prescribing drug therapy. Self-reported initial management of ITP by ASPH/O members in 2001 is similar to 1997 regarding the percentage of pediatric hematologists who would not use drug therapy. Among physicians who would use drug treatment, there was an increased use of anti-D and decreased use of IVIG and prednisone. This information provides the basis for designing a randomized clinical trial to compare the effect of different management strategies on the outcomes of bleeding symptoms, side effects of therapy, costs, and quality of life.

Adult↗