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Terrence W Hallahan

Publications and source records attributed to Terrence W Hallahan.

6 recordsLinked to original sources
PubMed2005

Maternal weight and ethnic adjustment within a first-trimester Down syndrome and trisomy 18 screening program.

OBJECTIVE(S): To estimate weight and ethnic group correction factors for first-trimester screening markers. METHODS: Ethnic-specific median MoM free beta hCG and pregnancy associated plasma protein A (PAPP-A) and delta nuchal translucency values were calculated for cohorts of maternal weight (20 lb each) using data from 51,206 patients undergoing first-trimester screening. False-positive rates for Down syndrome and trisomy 18 were evaluated both prior to and after weight and ethnicity adjustment. RESULTS: Free beta hCG and PAPP-A significantly decreased with increasing maternal weight while nuchal translucency increased by a clinically insignificant amount. For free beta hCG the regression formula indicated that after accounting for maternal weight MoM values were 16% higher for African Americans, 6% higher for Asians and 9% lower for Hispanics compared to Caucasians (p < 0.001, p = 0.001, p < 0.001, respectively) but there was no significant difference for Asian Indians. For PAPP-A, MoM values were 35% higher for African Americans (p < 0.001) but were not significantly different for the other ethnic groups compared to Caucasians. Down syndrome false-positive rates did not vary with maternal weight prior to (p = 0.291) or after weight adjustment of biochemistry (p = 0.054). Trisomy 18 false-positive rates varied significantly with weight both before (OR = 1.455 per 20-pound increase, p < 0.001) and after (OR = 1.066 per 20-pound increase, p = 0.01) weight adjustment of biochemistry; however, the odds ratio was greatly reduced after weight adjustment. CONCLUSION(S): The first-trimester screening markers, free beta hCG, PAPP-A and nuchal translucency vary with maternal weight and ethnicity. Adjustment of free beta hCG and PAPP-A is indicated but adjustment of nuchal translucency results may not be necessary.

Body Weight↗
PubMed2005

First-trimester screening for trisomy-21 using a simplified method to assess the presence or absence of the fetal nasal bone.

OBJECTIVE: To determine the benefit of including nasal bone assessment in addition to standard first-trimester markers (nuchal translucency, free beta human chorionic gonadotropin and pregnancy-associated plasma protein A) as a screening test for Down syndrome, using a strict criterion for classification of nasal bone absence. STUDY DESIGN: Nasal bone assessment was conducted in 2411 patients with crown-rump length between 45 and 84 mm, including 15 patients with Down syndrome. A patient was considered to have an absent nasal bone only if there was no evidence of present nasal bone. Unlike other studies, nasal bone was classified as present when there was evidence of a thin echogenic line under the skin. Simulation studies were conducted to assess the detection rate and false-positive rate of a combined first-trimester screening protocol including nasal bone assessment. RESULTS: There were 9 of 2396 (0.4%) unaffected cases with absent nasal bone (95% confidence interval 0.2%, 0.7%) and 8 of 15 (53.3%) Down syndrome cases (95% confidence interval 26.6%, 78.7%). Using a 1 in 250 risk cut-off, the detection rate of standard first-trimester screening was 87%, with a false-positive rate of 4.3%. Incorporating nasal bone measurement improved the detection rate of Down syndrome to 90% and reduced the false-positive rate to 2.5%. CONCLUSION: The use of a strict criterion to determine nasal bone absence leads to fewer cases classified as absent and may simplify the implementation of nasal bone as a marker for first-trimester screening, resulting in lower false-positives and higher detection, compared with other current screening protocols.

Adult↗
PubMed2004

Association of extreme first-trimester free human chorionic gonadotropin-beta, pregnancy-associated plasma protein A, and nuchal translucency with intrauterine growth restriction and other adverse pregnancy outcomes.

OBJECTIVE: The purpose of this study was to determine the association between first-trimester trisomy 21 screening markers (free human chorionic gonadotropin-beta [hCG], pregnancy-associated plasma protein A [PAPP-A], and nuchal translucency) and adverse pregnancy outcome. STUDY DESIGN: This was a cohort study of 8012 patients enrolled in a National Institute of Child Health and Human Development-sponsored study of first-trimester trisomy 21 and 18 screening. Trisomy 21 and 18 risk results and individual marker levels in unaffected pregnancies and pregnancies with adverse outcomes were evaluated. RESULTS: PAPP-A <1st percentile (OR 5.4, 95% CI 2.8-10.3) and PAPP-A <5th percentile (OR 2.7, 95% CI 1.9-3.9) and free beta-hCG <1st percentile (OR 2.7, 95% CI 1.3-5.9) were associated with increased risk of intrauterine growth restriction (IUGR) with positive predictive values of 24.1%, 14.1%, and 14.3%, respectively. PAPP-A <5th percentile (OR 2.3 95% CI 1.1-4.7) and nuchal translucency >99th percentile (OR 3.5, 95% CI 1.1-11.3) were associated with increased risk of preterm delivery before 34 weeks. Increased risk at screening for trisomy 21 and 18 identified 16 of the 29 other chromosomal abnormalities (55%). Low free beta-hCG, low PAPP-A, and increased nuchal translucency were all associated with an increased rate of fetal abnormality. CONCLUSION: Extreme values of first-trimester free beta-hCG, PAPP-A, and nuchal translucency are all associated with adverse outcomes. The especially high predictive value for IUGR of PAPP-A levels below the 1st percentile suggests that patients within this group may benefit from increased surveillance for this condition.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMed2003

Combined first-trimester versus second-trimester serum screening for Down syndrome: a cost analysis.

OBJECTIVE: The purpose of this study was to compare the cost-effectiveness of combined first-trimester screening for fetal Down syndrome with second-trimester maternal serum triple screening. STUDY DESIGN: A first-trimester screening approach that used nuchal translucency measurement and maternal serum screening was evaluated against second-trimester maternal serum triple screening in a hypothetic population. Screening sensitivities and screen-positive rates were 91% and 5% for the first-trimester approach and 70% and 7.5% for the second-trimester approach, respectively. The costs of fetal Down syndrome, live-born Down syndrome cost, and total costs (screening plus live-born costs) were calculated for each screening program. RESULTS: First-trimester screening was associated with lower screening and live-born Down syndrome costs versus second-trimester serum screening. Total Down syndrome screening costs were 29.1% lower with first-trimester screening. CONCLUSION: In this hypothetic model, combined first-trimester screening for fetal Down syndrome was more cost-effective than universal second-trimester triple serum screening.

Adult↗