Combined first-trimester screening in northern Finland: experiences of the first ten years.

OBJECTIVE: To evaluate the efficacy of first trimester combined screening for Down's syndrome in Northern Finland during the first 10 years of practice. METHODS: During 1 January 2002 to 31 December 2011, 47,896 women participated voluntarily in combined screening during first trimester. The risk cutoff was 1:250. The study period was divided into two time periods; 2002-2006 and 2007-2011. RESULTS: During the first half of the study period, the detection rate (DR) was 77.3% with a 4.9% false-positive rate (FPR). During the latter half, the DR was 77.1% with a 2.8% FPR. CONCLUSIONS: An important issue is the number of invasive procedures needed to detect one case of Down's syndrome. The screening performance improved markedly in the latter five years period since the FPR lowered from 4.9% to 2.8% and the number of invasive procedures needed to detect one case of Down's syndrome lowered from 15 to 11.

Comparison of combined, biochemical and nuchal translucency screening for Down syndrome in first trimester in Northern Finland.

OBJECTIVE: To compare the efficacy of fetal nuchal translucency screening, maternal serum screening and combined screening for Down syndrome. DESIGN: A prospective study. SETTING: University hospital and its public health care district in Northern Finland. POPULATION: A total of 35,314 women participated in the first-trimester screening for Down syndrome within the public healthcare system in 2002-08. There were 95 pregnancies involving Down syndrome. Serum samples were obtained from 35,314 women, nuchal translucency was measured in 27,144 pregnancies and full combined screening was performed in those pregnancies, including 76 involving Down syndrome. METHODS: The adjusted estimated risk for Down syndrome was calculated using the Perkin Elmer AutoDELFIA® time-resolved fluoroimmunoassay kit for the measurement of pregnancy-associated plasma protein-A and free ß-human chorionic gonadotropin. Nuchal translucency was measured by trained personnel in a university or district hospital. Risk cut-off figures 1:250 and 1:300 at term were used. MAIN OUTCOME MEASURES: Differences in detection rate, false-positive rate, positive and negative predictive values between nuchal translucency screening, serum screening and combined screening. RESULTS: Using the risk cut-off figure 1:250, the detection rates for serum screening, nuchal translucency screening and combined screening were 64.2, 64.5 and 72.4%, respectively and the false-positive rates were 7.8, 4.4 and 4.0%, respectively. CONCLUSIONS: Combined screening is the method of choice for Down syndrome screening in Finland.

Adding ADAM12 in risk calculation program does not improve the detection rate of trisomies 18 and 13 in first trimester screening.

OBJECTIVE: To investigate first trimester levels of ADAM12 in trisomy 18 and 13 pregnancies and whether incorporating ADAM12 in the LifeCycle™ risk calculation program of trisomy 18 and trisomy 13 screenings can improve the detection rates of trisomies 18 and 13. METHODS: ADAM12 was incorporated in the LifeCycle™ risk calculation program. A specific algorithm with cut-off of 1:200 for screening of trisomies 18 and 13 was employed. Detection rates for trisomies 18 and 13 were calculated. RESULTS: There was a significant difference in ADAM12 levels between trisomy 18 pregnancies and controls during the gestation weeks 9 + 0 - 10 + 6, but not thereafter. In trisomy 13 pregnancies there was no difference in weeks 9 + 0 - 10 + 6, but there was in 11 + 0 - 12 + 6. The specific algorithms for trisomies 18 and 13 combined with algorithm for trisomy 21 yielded detection rates of 73.7% and 66.7%, respectively. The combined false positive rate was 4.6%. Adding ADAM12, the detection rate for trisomy 18 was the same, at 73.7% and for trisomy 13, at 66.7%. CONCLUSION: ADAM12 did not improve the detection rate.

Screening and outcome of chromosomal abnormalities other than trisomy 21 in Northern Finland.

OBJECTIVE: To examine the performance of first-trimester combined screening after adding the specific algorithms for trisomies 18 and 13 in the Down syndrome screening program for chromosomal abnormalities other than trisomy 21 and to determine the outcomes of such pregnancies. DESIGN: A retrospective study. SETTING: Oulu University Hospital, Finland. POPULATION: Pregnant women (n=56 076) participating voluntarily in first-trimester combined Down syndrome screening in Northern and Eastern Finland during the study period 1 June 2002 to 31 December 2008. METHODS: The data of all known cases of chromosomal abnormalities other than trisomy 21 were collected. MAIN OUTCOME MEASURES: Risk algorithms for trisomies 21, 18 and 13 were used for the calculation of patient-specific risks for certain chromosomal abnormalities. Algorithms were based on maternal age, crown-rump length, nuchal translucency, and measurement of free ß-human chorionic gonadotrophin and pregnancy-associated plasma protein-A. Detection rates and false-positive rates were calculated. RESULTS: A total of 27 cases of trisomy 18, 11 cases of trisomy 13 and 30 cases of other chromosomal abnormalities were analyzed. The algorithm for Down syndrome detected 55.6% of trisomy 18 cases, 36.4% of trisomy 13 cases and 60.0% of other chromosomal abnormalities. When specific risk algorithms were added, the detection rates improved for trisomy 18 (74.0%) and for trisomy 13 (54.5%), with only a slight increase of the false-positive rate of 0.2%. The detection rate for other chromosomal abnormalities did not improve. CONCLUSIONS: Adding the trisomy 18 algorithm to the Down screening program resulted in the detection of five additional trisomy 18 cases.

More invasive procedures are done to detect each case of Down's syndrome in younger women.

OBJECTIVE: To evaluate the performance of first-trimester combined screening in 5-year periods according to maternal age in a low-risk population. DESIGN: A prospective study. SETTING: Multicenter study in Finland. POPULATION: A total of 76949 voluntary women with singleton pregnancies participated in first-trimester combined screening in public healthcare between 1 May 2002 and 31 December 2008. METHODS: The serum samples were analyzed using the PerkinElmer AutoDELFIA® time-resolved fluoroimmunoassay kit for the measurement of pregnancy-associated plasma protein-A and free beta-human chorionic gonadotropin. Nuchal translucency was measured by trained personnel (midwives or physicians) in a university or central hospital. MAIN OUTCOME MEASURES: Performance, detection rate, false positive rate and the number of invasive procedures needed to detect a single case of Down's syndrome were analyzed. RESULTS: There was a direct connection between maternal age and the prevalence of Down's syndrome with a low prevalence in young women being 1:1 193 in the 25-29 age group and 1:150 in the 35-39 age group. Consequently, for a fixed false positive rate of 5%, the number of invasive procedures needed to detect one case of Down's syndrome is higher in younger women to achieve the same detection rate. CONCLUSIONS: In combined first trimester screening the risk for Down's syndrome is individual, varying with maternal age. This should be taken into consideration when counseling women.