Neonatal screening for sickle cell disease in France: evaluation of the selective process.

AIMS: The French national programme for neonatal screening of sickle cell disease is applied to newborns 'at risk', defined as those born to parents originating from sub-Saharan Africa, the Mediterranean area, the Arabic peninsula, the French overseas islands and the Indian subcontinent. The selection is performed by the nurse in charge of blood sampling by interviewing the mother about the family's geographical origins. The mean rate of testing in France is 25%, ranging from 2% to 50% depending on the region. This study aimed to evaluate the effectiveness of selection during this screening programme.
METHODS: False-negative cases were identified using two different approaches: first, a regional prospective study aimed at screening all newborns, selected and non-selected, in a restricted area, representing 3% of national births; second, a retrospective national survey to identify false-negative cases.
RESULTS: The regional study indicated that selective screening leads to a carrier frequency that is twice as high in the selected population as compared with the non-selected population (1.23% versus 0.62%). The local and national surveys revealed that, during a 6-year period, 28 affected children failed to be selected, leading to a false-negative rate of 2.1%. In contrast to what was expected, most of the cases were due to the failing of the data collection process and not to the misdiagnosis of the risk.
CONCLUSIONS: These results show that selective neonatal screening for sickle cell disease is feasible if very careful attention is paid to the selective step.