The value of screening for Down's syndrome in a socioeconomically deprived area with a high ethnic population

Abstract

Objective: To assess the utility of biochemical antenatal screening for Down's syndrome in a socioeconomically deprived area with a high proportion of Asian women from the Indian Subcontinent.

Design: Audit of Down's syndrome biochemical screening service over a four-year period.

Setting: Teaching hospital and community antenatal clinic in inner city Birmingham.

Population: Women booked between October 1992 and December 1996.

Methods: Blood for screening was collected between 14 and 21 weeks gestation, alpha-fetoprotein and intact human chorionic gonadotrophin were measured in serum and the risk of Down's syndrome was calculated.

Main outcome measures: Uptakes of screening and amniocentesis, screen positive rate, odds of being affected given a positive result, miscarriages associated with amniocentesis offered following a high risk result, detection rate, number of Down's cases prevented and a cost analysis. Outcome measures were compared between Asians and Caucasians.

Results: Overall 11,974 women (71%) accepted serum screening. The screen positive rate was 8.3% in Asians and 5.0% in Caucasians. The uptake of amniocentesis in women following a high risk result was 54% overall (35% Asian, 67% Caucasian). Nineteen cases of Down's syndrome were identified, of which 13 occurred in women who opted for biochemical screening. The detection rate of the biochemical screening programme was 85% (11/13). Of these 11 cases, six (none of whom were Asian) elected to have an amniocentesis, of whom four thereafter had a termination.

Conclusion: In this study the public health benefits of screening for Down's syndrome in a socioeconomically deprived area with a high Asian population, were small.