One-third of the new paediatric patients with sickle cell disease in The Netherlands are immigrants and do not benefit from neonatal screening.

Objectives: To estimate the prevalence of children with sickle cell disease (SCD) in The Netherlands. To estimate the annual number of children newly diagnosed as having SCD and the proportion with diagnoses through neonatal screening To estimate the proportion of children with SCD receiving paediatric care in a comprehensive care setting.

Design: Data from two sources, a survey of paediatric practices (n=107) and a laboratory database (n=20), were analysed by the capture-recapture method.

Participants: Children with SCD aged <18 years, either born before 2003 or newly diagnosed as having SCD between 2003 and 2007.

Main Outcome Measures: Prevalence, annual number of children newly diagnosed as having SCD, proportion of children with diagnoses through neonatal screening, proportion of children receiving paediatric care.

Results: The prevalence of SCD in children living in The Netherlands on 1 January 2003 was 1:5152 (95% CI 1:4513 to 1:6015). In the next 4 years, the annual incidence was 1:2011 (95% CI 1:1743 to 1:2376). Nearly one-third (27%) of the children newly diagnosed as having SCD immigrated to The Netherlands after birth and would, therefore, be missed by the neonatal screening programme. Approximately 60% of all children with SCD were not reported by paediatricians.

Conclusion: The number of children with SCD in The Netherlands is much higher than previously estimated, and the majority of these children seem not to be reviewed regularly by a paediatrician. Children born abroad (27% of new cases) do not benefit from neonatal screening and are at high risk of life-threatening complications before SCD is diagnosed. As this introduces disparities in healthcare, the initiation of adequate measures should be considered.