Mapping the prevalence of sickle cell and beta thalassaemia in England: estimating and validating ethnic-specific rates

A range of estimates for sickle cell and beta thalassaemia hare been derive d for the different ethnic groups living in the U.K., reflecting uncertaint y over the true population value in certain countries and the heterogeneity within and between countries of origin comprising the same ethnic group. T hese were validated against sis community screening programmes, with the es timated range correctly predicting the number of affected births observed b y the programmes. In England approximately 3000 affected babies (0.47%) carry sickle cell tra it and 2800 (0.44%) carry beta thalassaemia trait annually; with approximat ely 178 (0.28 per 1000 conceptions) affected by sickle cell disease (SCD) a nd 43 (0.07 per 1000) by beta thalassaemia major/intermedia. Allowing for t ermination, about 140-175 (0.22-0.28 per 1000) affected infants are born an nually with SCD and from 10 to 25 (0.02-0.04 pr 1000) with beta thalassaemi a maior/intermedia, These are the first evidence-based rates for sickle cell and beta thalassae mia for use in the U.K., and should underpin the future planning of service s, The long-term solution to monitoring changes in the rates of trait and d isease in the population is to introduce a standardized instrument for coll ecting ethnicity for all community screening programmes.