- 學位論文
台灣母血唐氏症篩檢對唐氏症出生趨勢之影響
The impact of the maternal serum screening program on Down syndrome birth trend in Taiwan
摘要
唐氏症是造成智障最常見的染色體異常原因，在台灣發生率約為1/800。懷孕母親的年齡更是生出唐氏症的一項危險因素，年齡愈高，生出唐氏症兒的機率愈大。然而有80％唐氏症胎兒都是出生在小於34歲的年輕孕婦，加上目前科技業越發達，婦女越來越多晚婚的傾向，所以目前這些因素都是我們所需要正視的問題。 台灣自1994年起最早由台大醫院開始引進了母血唐氏症篩檢（Maternal Serum Screening for Down Syndrome,MSS-DS），而過去在1994至2001年已有人做過在台灣唐氏症出生趨勢的影響[1]，於母血唐氏症篩檢1994 年介入之前後，唐氏症之活產比率逐漸降低，而死產比率逐漸提昇，故本研究加強並延續2001-2011年對於台灣唐氏症之出生趨勢的變化，再來這幾年不斷有新的篩檢方式更新、進步中，藉此比照這些新的篩檢方式的加入是否有帶給台灣唐氏症出生趨勢的影響。此外本研究再加上國內台大醫院2006至2011年唐氏症篩檢實施之成效。 而台大醫院在執行唐氏症篩檢方面更是因應目前的產前篩檢潮流趨勢進行，第一孕期頸部透明帶唐氏症篩檢在2006年九月至2011年收案共3899名單胞胎，篩檢為高風險有107名，診斷為唐氏症有2名，在偽陽性2.7%之下 ，檢出率達100%。第一孕期唐氏症篩檢為中間風險值有211名，診斷為唐氏症有1名，在偽陽性5.1%下，檢出率達100%。而第二孕期四指標母血唐氏症篩檢則是從2008年五月開始引進，統計到2011年這三年多之間，共收案1268名單胞胎，有110位孕婦篩檢為高風險，偵測出唐氏症3名，漏掉1名，在本次統計中本院的唐氏症四指標篩檢檢出率為75%，偽陽性8%。 台灣的唐氏症活產盛行率在本次研究資料中，於2001至2010年之間顯示出有減少的趨勢，尤其在2007年之後從0.69下降至0.46，甚至於2009年降低至每一萬名活產中有0.26的唐氏症兒出生。 實施全面母血唐氏症篩檢之政策是 1994 年以來台灣唐氏症兒減少的主要原因，在近年來更是隨著不同的篩檢組合方式不斷在進步而造成唐氏症出生趨勢持續降低。母血唐氏症篩檢推出之後對唐氏症之檢出有所幫助，也符合經濟效益，但如何增加偵測率、減少偽陽性率以避免不必要之侵入性檢查，減少流產的風險都是目前努力的目標。
並列摘要
Down syndrome is the most common chromosomal cause of mental retardation. In Taiwan, the incidence is reported to be around 1 in 800 live births. Maternal age is a significant risk factor for Down syndrome; the higher the age at conception, the greater the chances of bearing a child with Down syndrome. Even so, 80% of Down babies are born to women younger than 34 years of age. At the same time, due to increased industrialization of our society, many women now have full time careers and elect to marry at an older age. All these are issues which we need to address while trying to detect Down syndrome prenatally. In Taiwan, the maternal serum screening test for Down syndrome (MSS-DS) was first introduced in 1994 by the National Taiwan University Hospital. In the past, studies have been performed which collected data from 1994 to 2001. They compared trends in the live birth rates of Down syndrome before and after starting the use of MSS-DS in 1994. A trend of decreasing live birth rates associated with an increase rate of fetal demise in Down fetuses was noted. Our study is a continuation of the previous studies and includes data from 2001 to 2011. We wish to see if progress in Down screening methods further reduce the overall Down birth rates. In addition, this study is an objective evaluation of the results of implementing universal Down screening at National Taiwan University Hospital in the period between 2006 and 2011. At National Taiwan University Hospital, Down screening is vigorously performed in response to the current societal expectations. From September 2006 to 2011, 3899 singleton pregnancies were enrolled for the first trimester nuchal translucency with Down syndrome screening. One hundred and seven cases were designated high-risk, within which 2 were diagnosed with Down syndrome. This yielded a false positive rate of 2.7%, and a detection rate of 100%. Two hundred and eleven cases were designated as intermediate risk, with one case being diagnosed with Down syndrome. This translated to a false positive rate of 5.1%, and a detection rate of 100% The second trimester four marker serum screening test was first introduced in May of 2008. In the past three years of employing the test, we have accrued 1268 singleton pregnancies. A hundred and ten pregnancies were designated high-risk. Three patients were subsequently diagnosed with Down syndrome. However, one case in the low risk group was diagnosed with Down syndrome. This results in an overall detection rate of 75% and a false positive rate of 8% for the four marker screening test. In this study, the prevalence of Down syndrome in Taiwan shows a decreasing trend between 2001 and 2010.The decrease is especially evident after 2007, which documented a dropped in Down prevalence from 0.69 to 0.46. In 2009, the prevalence was further reduced to 0.26 per 100,000 live birth. Implementation of universal maternal serum screening policy is the main reason for the decreasing incidence of children born with Down syndrome in Taiwan since 1994. In recent years, with progresses in different combination screening tests, incidence of Down syndrome is further reduced. After starting the maternal serum screening for Down syndrome in 1994, we have found that the tests are both efficient and beneficial. Future goals include methods to improve detection rates and to reduce false positive rates in order to avoid unnecessary invasive procedures, which might have resulted in unintended abortions.