Early splenectomy in a large cohort of children with sickle cell anemia: risks and consequences.

In children with sickle cell anemia (SCA), early splenic complications can require splenectomy, but the benefit-to-risk ratio and the age at which splenectomy may be safely performed remain unclear. To address this question, we analyzed the rate of post-splenectomy events in children with SCA splenectomized between 2000-2018 at the Robert Debré University Hospital, Paris, France. A total of 188 children underwent splenectomy, including 101 (11.9%) from our newborn cohort and 87 referred to our center. Median (Q1-Q3) age at splenectomy was 4.1 years (range 2.5-7.3 years), with 123 (65.4%) and 65 (34.6%) children splenectomized at ≥3 years of age or <3 years of age, respectively. Median postsplenectomy follow-up was 5.9 years (range 2.7-9.2 years) yielding 1192.6 patient-years (PY) of observation. Indications for splenectomy were mainly acute splenic sequestration (101 [53.7%]) and hypersplenism (75 [39.9%]). All patients received penicillin prophylaxis; 98.3% received 23-valent polysaccharic pneumococcal (PPV-23) vaccination, and 91.9% a median number of 4 (range 3-4) pneumococcal conjugate vaccine shots prior to splenectomy. Overall incidence of invasive bacterial infection and thrombo-embolic events were 0.005 / PY (no pneumococcal infections) and 0.003 / PY, respectively, regardless of age at splenectomy. There was an increased proportion of children with cerebral vasculopathy in children splenectomized <3 years of age (0.037 / PY vs. 0.011 / PY; P<0.01). A significantly greater proportion of splenectomized than non-splenectomized children were treated with hydroxycarbamide (77.2% vs. 50.1%; P<0.01), suggesting a more severe phenotype in children who present spleen complications. If indicated, splenectomy should not be delayed in children, provided recommended pneumococcal prophylaxis is available. Spleen complications in childhood may serve as a marker of severity.

Variability of Prognostic Results Based on Biological Parameters in Sickle Cell Disease Cohort Studies in Children: What Should Clinicians Know?

BACKGROUND: Many pediatric studies describe the association between biological parameters (BP) and severity of sickle cell disease (SCD) using different methods to collect or to analyze BP. This article assesses the methods used for collection and subsequent statistical analysis of BP, and how these impact prognostic results in SCD children cohort studies. METHODS: Firstly, we identified the collection and statistical methods used in published SCD cohort studies. Secondly, these methods were applied to our cohort of 375 SCD children, to evaluate the association of BP with cerebral vasculopathy (CV). RESULTS: In 16 cohort studies, BP were collected either once or several times during follow-up. The identified methods in the statistical analysis were: (1) one baseline value per patient (2) last known value; (3) mean of all values; (4) modelling of all values in a two-stage approach. Applying these four different statistical methods to our cohort, the results and interpretation of the association between BP and CV were different depending on the method used. CONCLUSION: The BP prognostic value depends on the chosen statistical analysis method. Appropriate statistical analyses of prognostic factors in cohort studies should be considered and should enable valuable and reproducible conclusions.

Continuous Manual Exchange Transfusion for Patients with Sickle Cell Disease: An Efficient Method to Avoid Iron Overload.

Children with sickle cell anemia (SCA) may be at risk of cerebral vasculopathy and strokes, which can be prevented by chronic transfusion programs. Repeated transfusions of packed red blood cells (PRBCs) is currently the simplest and most used technique for chronic transfusion programs. However, iron overload is one of the major side effects of this therapy. More developed methods exist, notably the apheresis of RBC (erythrapheresis), which is currently the safest and most efficient method. However, it is costly, complicated, and cannot be implemented everywhere, nor is it suitable for all patients. Manual exchange transfusions combine one or more manual phlebotomies with a PRBC transfusion. At the Reference Center of Sickle Cell Disease, we set up a continuous method of manual exchange transfusion that is feasible for all hospital settings, demands no specific equipment, and is widely applicable. In terms of HbS decrease, stroke prevention, and iron overload prevention, this method showed comparable efficiency to erythrapheresis. In cases where erythrapheresis is not available, this method can be a good alternative for patients and care centers.

Improvement of medical care in a cohort of newborns with sickle-cell disease in North Paris: impact of national guidelines.

We conducted a retrospective study on newborns with sickle-cell disease (SCD), born 1995-2009, followed in a multicentre hospital-based network. We assessed patient outcomes, medical care and compliance with the national guidelines published in December 2005. Data from 1033 patients (742 SS/Sß°-thalassaemia) with 6776 patient-years of follow-up were analysed (mean age 7·1 ± 3·9 years). SCD-related deaths (n = 13) occurred only in SS-genotype patients at a median age of 23·1 months, mainly due to acute anaemia (n = 5, including 2 acute splenic sequestrations) and infection (n = 3). Treatment non-compliance was associated with a 10-fold higher risk of SCD-related death (P = 0·01). Therapeutic intensification was provided for all stroke patients (n = 12), almost all patients with abnormal transcranial Doppler (TCD) (n = 76) or with >1 acute chest syndrome/lifetime (n = 64) and/or ≥3 severe vaso-occlusive crises/year (n = 100). Only 2/3 of patients with baseline haemoglobin <70 g/l received intensification, mainly for other severity criteria. Overall, hydroxycarbamide was under-prescribed, given to 2/3 of severe vaso-occlusive patients and 1/3 of severely anaemic patients. Nevertheless, introduction of the on-line guidelines was concomitant with an improvement in medical care in the 2006-2009 cohort with a trend towards increased survival at 5 years, from 98·3% to 99·2%, significantly increased TCD coverage (P = 0·004) and earlier initiation of intensification of therapy (P ≤ 0·01).

Clinical and haematological risk factors for cerebral macrovasculopathy in a sickle cell disease newborn cohort: a prospective study.

Children with sickle cell disease (SCD) have a significant vascular morbidity, especially cerebral macrovasculopathy (CV), detectable by transcranial Doppler. This study aimed to identify risk factors for CV using longitudinal biological and clinical data in a SCD newborn cohort followed at the Robert Debre Reference centre (n = 375 SS/Sß(0) ). Median follow-up was 6·8 years (2677 patient-years). Among the 59 children presenting with CV, seven had a stroke. Overall, the incidence of CV was 2·20/100 patient-years [95% confidence interval (95% CI): 1·64-2·76] and the incidence of stroke was 0·26/100 patient-years (95% CI: 0·07-0·46). The cumulative risk of CV by age 14 years was 26·0% (95% CI: 20·0-33·3%). Risk factors for CV were assessed by a Cox model encompassing linear multivariate modelling of longitudinal quantitative variables. Years per upper-airway obstruction [Hazard ratio (HR) = 1·47; 95% CI: 1·05-2·06] or bronchial obstruction (HR = 1·76; 95% CI: 1·49-2·08) and reticulocyte count (HR = 1·82 per 50 × 10(9) /l increase; 95% CI: 1·10-3·01) were independent risk factors whereas fetal haemoglobin level (HR = 0·68 per 5% increase; 95% CI: 0·48-0·96) was protective. Alpha-thalassaemia was not protective in multivariate analysis (ancillary analysis n = 209). Specific treatment for upper or lower-airway obstruction and indirect targeting of fetal haemoglobin and reticulocyte count by hydroxycarbamide could potentially reduce the risk of CV.

Impact of glucose-6-phosphate dehydrogenase deficiency on sickle cell anaemia expression in infancy and early childhood: a prospective study.

In patients with sickle cell anaemia (SCA), concomitant glucose-6-phosphate dehydrogenase (G6PD) deficiency is usually described as having no effect and only occasionally as increasing severity. We analysed sequential clinical and biological data for the first 42 months of life in SCA patients diagnosed by neonatal screening, including 27 G6PD-deficient patients, who were matched on sex, age and parents' geographic origin to 81 randomly selected patients with normal G6PD activity. In the G6PD-deficient group, steady-state haemoglobin was lower (-6·2 g/l, 95% confidence interval (CI), [-10·1; -2·3]) and reticulocyte count higher (247 × 10(9) /l, 95%CI, [97; 397]). The acute anaemic event rate was 3 times higher in the G6PD-deficient group (P < 10(-3) ). A higher proportion of G6PD-deficient patients required blood transfusion (20/27 [74%] vs. 37/81 [46%], P < 10(-3) ), for acute anaemic events, and also vaso-occlusive and infectious events. No significant between-group differences were found regarding the rates of vaso-occlusive, infectious, or cerebrovascular events. G6PD deficiency in babies with SCA worsens anaemia and increases blood transfusion requirements in the first years of life. These effects decrease after 2 years of age, presumably as the decline in fetal haemoglobin levels leads to increased sickle cell haemolysis and younger red blood cells with higher G6PD activity.