Commentary on Down syndrome screening in China.

Abstract

Prenatal screening for fetal Down syndrome has been widely practised in China for many years. In this special issue of BJOG, Tu et al. have published a systematic review on the performance of prenatal screening tests using biochemical and sonographic markers in Chinese women (Tu et al. BJOG 2016). Among the 78 included studies, of which most were from China, the majority (n = 64, 82%) were based on second-trimester biochemical markers. Although the pooled sensitivity and specificity for the second-trimester markers were 0.79 and 0.96, respectively, there were wide variations among individual studies. Most interestingly, 13 of the 64 second-trimester studies had a sensitivity of over 90%. Such an excellent performance has rarely been reported in studies from the non-Chinese population (Alldred et al. Cochrane Database Syst Rev 2012 Jun 13;(6):CD009925). This raised a concern over the quality of individual studies that warranted detailed analysis. In contrast, Li et al. reported in detail how to implement successfully a first-trimester combined screening (FTCS) programme for fetal Down syndrome in a resource-limited area of mainland China (Li et al. BJOG 2016). Despite the resource limitations, the author had followed strictly all the steps that were important for a successful screening programme, namely training and accreditation of staff, generation and use of local data, development of a customised cut-off and continuous quality assurance for both sonographers and biochemical assays. Specifically, the quality assurance steps included the following: (1) all sonographers were accredited by the Fetal Medicine Foundation and re-certified annually; (2) the performance of each sonographer was continuously monitored using a rolling standardised audit quality assurance report; (3) the multiple of the median values of individual biochemical markers were assessed monthly to determine the central tendency and dispersion; and (4) outcome data were followed-up. The above steps allowed early identification of deviation from expected performance for which early intervention could be initiated. Certification and quality assurance of sonographers is a particularly difficult process, requiring the support and cooperation of hospital administrators. It is interesting that in Li et al.'s study the cost of FTCS was quoted to be RMB800. Based on screening performance, noninvasive prenatal testing (NIPT) for fetal Down syndrome by cell-free DNA in maternal plasma is a far better test than FTCS, having a sensitivity and a specificity both above 99%. The cost of NIPT has come down substantially over the past 2 years. In China, NIPT is available in many major cities at a current user price most commonly between RMB2000 and 3000. It should not be long before the cost of NIPT is comparable to that of FTCS. At present, many hospitals in China are developing their own in-house NIPT platforms. This is a suboptimal move because such small hospital-based laboratories will not have enough volume to maintain a meaningful quality assurance programme. It is advisable that these screening programmes are coordinated within a region and centralised in one or a few centres where a strict quality assurance programme could be implemented. Even if NIPT has replaced conventional screening, the concept of ‘quality assurance’ as demonstrated in the study by Li et al. remains the key to the success for all screening programmes. None declared. Completed disclosure of interests form available to view online as supporting information. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.