Efficiency of the Neonatal Screening Program for Sickle Cell Disease. the Belgian Experience

Abstract 4816

The objective of this study was to determine the efficiency of the neonatal screening program for SCD which was implemented in 1994 in few maternities and extended in 2003 to all maternities in Brussels. It is a systematic screening performed on liquid cord blood. Affected children are referred to a specialized center. We reviewed 146 medical records of patients with SCD born in Belgium and prospectively followed from the time of their diagnosis in three Brussels' Academic Centers. The study was approved by each local ethical committee and informed consent of each patient was received. Data were collected from the time of diagnosis of SCD (either done by neonatal screening or when a clinical event led to the diagnosis) until December 31, 2007. We focused on the subgroup of patients older than 3 years of age at December 31, 2007 and those were divided into two groups: those diagnosed by the neonatal screening (NS) and those diagnosed later (no NS). The incidence of major events (first septicemia, first stroke, first episode of severe anemia, first hospitalization and its duration, and death) was compared. Among the total population studied, 89 patients were diagnosed through the NS and 57 were not (no NS). While among those older than 3 years of age at the time of evaluation, 55 (median age 6.7 year, range: 3–16) and 49 (median age 11.2 year, range: 4–27) patients were in the NS or no NS group, respectively. The median age at diagnosis for the no NS cohort is 1 year (range: 1–6). The follow-up of the NS and no NS cohort account for 301.5 and 473.8 patient-years, respectively. Most of the patients were homozygous for Hb S (Hb SS) (82% in NS group and 94% in no NS group). Incidence of a first episode of septicemia was similar in both groups (10.9% in NS group versus 12.3% in no NS group). The median age at the time of sepsis was 27.6 months and 10 months in the NS and no NS group, respectively (Table 1). All the patients from the NS group were on penicillin prophylaxis versus 40 % in the no NS group. The main pathogen remained Streptococcus pneumoniae and there were no resistant strain despite regular prophylaxis.

Incidence of stroke was 1.8% (1/55; 3.2 y.o.) in the NS cohort compared to 8.2% (4/49; 2.8, 5.3, 8.0 and 18.8 y.o.) in the no NS cohort. All the patients were Hb SS. The unique patient from the NS group was previously treated with Hydroxyurea (HU) for repeated vaso-occlusive crisis. 2 were also under HU prior to stroke for the same reason. Ischemic cerebral lesions were observed on MRI for all, except for the NS group patient. There was no significant difference either in the incidence of the first episode of severe anemia or the first hospitalization defined in term of number of days of hospitalization for both groups. Two deaths occurred in the NS cohort in the very early childhood (septicemia in one and acute severe anemia for the other). These deaths are attributable to no compliance to antibio-prophylaxis in the first patient and poor follow-up in the second one. Furthermore these deaths happen in the very early period after neonatal screening has been initiated. No death occurred in the NS group since 12 years probably due to better parents' education and comprehensive care. One death was observed in the no NS group (sudden rupture of cerebral aneurysm). In conclusion, neonatal screening program is feasible, safe and appropriate to detect SCD. It enables early diagnosis and therefore early treatment, and could improve both morbidity and eventually mortality of SCD. Although the relative small size of our study and the bias due to unreported early deaths by infection or severe anemia in the no NS group before the diagnosis of SCD has been done, our results are very encouraging: neonatal screening delays the age of the first severe infection and might reduce the incidence of early neurological complications. It also underlines the better outcome with improvement of parental education and comprehensive care. These data emphasize the need to continue neonatal screening for SCD in Brussels and to extend it to all Belgian maternities.